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"Early to Bed, Early to Rise": Diffusion Tensor Imaging Identifies Chronotype-Specificity.
... This dimension captures individuals that are referred to as 'night owls' (evening types) and 'morning larks' (morning types), as well as individuals in between. The first relevant study categorised healthy males into chronotypes (early, late and intermediate) and tested differences in five common measures of WM integrity: fractional anisotropy (FA), fibre count, and mean, axial, and radial diffusivities (MD, AD and RD, respectively) (Rosenberg et al., 2014). Compared to early or intermediate chronotypes, late chronotypes had altered WM integrity in regions of the frontal lobe, temporal lobe, and corpus callosum, suggesting evening types, on average, have poorer WM health (Rosenberg et al., 2014). ...
... The first relevant study categorised healthy males into chronotypes (early, late and intermediate) and tested differences in five common measures of WM integrity: fractional anisotropy (FA), fibre count, and mean, axial, and radial diffusivities (MD, AD and RD, respectively) (Rosenberg et al., 2014). Compared to early or intermediate chronotypes, late chronotypes had altered WM integrity in regions of the frontal lobe, temporal lobe, and corpus callosum, suggesting evening types, on average, have poorer WM health (Rosenberg et al., 2014). The second relevant study investigated genetic correlations between chronotype and WM integrity. ...
... lower FA in the posterior CR, increased AD and RD in the anterior CR, and increased RD in the CR). Among the limited studies of chronotype and WM, there are findings of lower FA in people with an evening (late) chronotype (Rosenberg et al., 2014), typically in frontal or temporal lobes or corpus callosum, which shares commonalities with our findings. One genome-wide association study observed negative genetic correlations among F I G U R E 3 Machine learning prediction of radial diffusivity (RD) as a measure of white matter integrity in young people with emerging mental disorders. ...
Protecting brain health is a goal of early intervention. We explored whether sleep quality or chronotype could predict white matter (WM) integrity in emerging mental disorders. Young people ( N = 364) accessing early‐intervention clinics underwent assessments for chronotype, subjective sleep quality, and diffusion tensor imaging. Using machine learning, we examined whether chronotype or sleep quality (alongside diagnostic and demographic factors) could predict four measures of WM integrity: fractional anisotropy (FA), and radial, axial, and mean diffusivities (RD, AD and MD). We prioritised tracts that showed a univariate association with sleep quality or chronotype and considered predictors identified by ≥80% of machine learning (ML) models as ‘important’. The most important predictors of WM integrity were demographics (age, sex and education) and diagnosis (depressive and bipolar disorders). Subjective sleep quality only predicted FA in the perihippocampal cingulum tract, whereas chronotype had limited predictive importance for WM integrity. To further examine links with mood disorders, we conducted a subgroup analysis. In youth with depressive and bipolar disorders, chronotype emerged as an important (often top‐ranking) feature, predicting FA in the cingulum (cingulate gyrus), AD in the anterior corona radiata and genu of the corpus callosum, and RD in the corona radiata, anterior corona radiata, and genu of corpus callosum. Subjective quality was not important in this subgroup analysis. In summary, chronotype predicted altered WM integrity in the corona radiata and corpus callosum, whereas subjective sleep quality had a less significant role, suggesting that circadian factors may play a more prominent role in WM integrity in emerging mood disorders.
... Given that the presentation format of the chronotype and alcohol consumption variables varied, the decision was made to conduct meta-analysis only if the data provided by the authors allowed for the dichotomization of both variables into evening chronotype or non-evening chronotype, and alcohol consumer or non-alcohol consumer. Hence, in studies that included three categories for chronotype (Arosemena et al. 2022;Garbazza et al. 2022;Hasler et al. 2017;Lee et al. 2022;Mule et al. 2022;Pereira-Morales et al. 2019;Rosenberg et al., 2014;Sansom et al. 2022), the neither-types and morning-types were combined and classified as non-evening types. Similarly, when alcohol consumption was reported as a continuous variable or presented in more than two categories for frequency, quantity, or type, any levels of consumption (in the case of continuous alcohol variable) (Ishihara et al. 1985) or all categories indicating alcohol consumption (if different levels of consumption were presented as categories) (Lee et al. 2022;Sansom et al. 2022;Siudej and Malinowska-Borowska 2021) were merged into a single category representing alcohol consumption, which was then compared to non-consumption (abstemious individuals). ...
... Meta-analytic procedures were possible for the association between chronotype and the dichotomous outcome of consuming or not consuming alcoholic beverages, for which data were provided in analysis categories only for 13 studies (Arosemena et al. 2022;Esposito et al. 2002;Garbazza et al. 2022;Ishihara et al. 1985;Lee et al. 2022;Pereira-Morales et al. 2019;Rosenberg et al. 2014;Sansom et al. 2022;Siudej and Malinowska-Borowska 2021;Vera et al. 2018;Zhang et al. 2018;Haraszti et al. 2014). While all manuscripts included in the meta-analysis assessed the chronotype using validated instruments, the consumption of alcohol was carried out through self-report of the participants, and the period of the questions varied from the recall of the last 24 hours (Vera et al. 2018 The pooled OR of alcohol consumption for eveningtype individuals compared to other chronotypes was 1.41 (95% CI: 1.16, 1.66; ...
... ), 3 weeks(Zhang et al. 2018) or 3 months(Lee et al. 2022), with most studies performing the questioning in general (current/present/regular consumption)(Arosemena et al. 2022;Garbazza et al. 2022;Pereira-Morales et al. 2019) or not specifying how it was questioned(Esposito et al. 2002;Haraszti et al. 2014;Ishihara et al. 1985;Rosenberg et al. 2014;Sansom et al. 2022;Siudej and Malinowska-Borowska 2021;Yang et al. 2019;Haraszti et al. 2014). ...
A broader understanding of whether and to what extent chronotype should be considered a risk factor for alcohol consumption is needed. The aim of this systematic review was to summarize the evidence on the association between evening chronotype and alcohol consumption. A systematic search of observational studies on this association was conducted in the PubMed, Scopus, Web of Science, Cochrane Library and PsycINFO databases up to April 30th, 2023. Random-effect models estimated the pooled odds ratio (OR) of alcohol consumption according to chronotype. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and Quality Assessment tool for Observational Cohorts and Cross-sectional Studies from the National Heart, Lung and Blood Institute were followed. A total of 33 studies involving 28 207 individuals (age range: 18–93 years) were included in this review. Overall, most studies indicated a higher volume and frequency of alcohol consumption in evening-type individuals than in individuals with different chronotypes. Additionally, a meta-analysis including 13 studies showed that evening-type individuals were 41% more likely to consume alcohol than those with other chronotypes (OR = 1.41, 95% confidence interval: 1.16–1.66; I2 = 38.0%). Limitations of the present findings are the predominance of cross-sectional studies and varied definitions of alcohol consumption. The available evidence supports an association between the evening chronotype and alcohol consumption. The evening-type population, especially young adults, is a specific target for educational interventions for preventing or reducing alcohol consumption.
... Collectively, these studies point to neurodevelopment as a mechanism linking sleep and adolescent outcomes (Galván, 2020), including, potentially, relations between morning-evening preference and psychopathology. Indeed, a growing volume of literature provides evidence of relationships between morning-evening preference and measures of both brain structure and function, including white matter microstructure (Rosenberg et al., 2014), cortical thickness (Rosenberg et al., 2018;Takeuchi et al., 2015) and reward-related brain activity (Hasler, Casement, et al., 2017). In addition, dysfunctional sleep behaviours commonly experienced by evening-oriented individuals (Vollmer et al., 2017), such as later sleep timing, poorer sleep quality and greater sleep variability, are also associated with variations in brain structure (Jalbrzikowski et al., 2021;Mulder et al., 2019;Telzer et al., 2015). ...
... Future work should seek to differentiate the specific effects of changes in sleep and chronotype on brain development in adolescence. Consistent with previous findings in children and adolescents (Mulder et al., 2019;Rosenberg et al., 2014), morning-evening preferences were associated with white matter structure at a global level, rather than displaying spatial specificity. These findings are consistent with functional neuroimaging studies showing that morning-evening preference influences a range of behaviours associated with multiple brain regions, implicated in a range of diverse functions. ...
... Direct measures of sleep, including presleep cognitions, were not collected in this study, precluding an opportunity to differentiate the respective roles of sleep and morning-evening preference on our selected outcomes. While previous studies have indicated that poor sleep is associated with deficits in brain structure (Jalbrzikowski et al., 2021;Kocevska et al., 2017;Takeuchi et al., 2018), literature in young adults highlights that neurobiological differences between morning-and evening-oriented individuals exist even after controlling for the effect of sleep quality (Rosenberg et al., 2014). As such, it is difficult to disentangle the direct effect of these respective processes on neurobiological outcomes, and future research should seek to do so. ...
Background
Morning–evening preference is defined as an individual's preference for a morning‐ or evening‐oriented rhythm. Across adolescence, a preference for eveningness becomes more predominant. Although eveningness is cross‐sectionally associated with internalizing and externalizing psychopathology, few studies have examined developmental changes in eveningness and its potential biological substrates. Here, we investigated the longitudinal relationships among the trajectory of eveningness preference, internalizing and externalizing psychopathology and white matter development, across adolescence.
Methods
Two‐hundred and nine adolescents (49% male) were assessed longitudinally at four separate time points between 12 and 19 years of age. Morning–evening preference and internalizing and externalizing symptoms were assessed at each time point. Diffusion‐weighted images were acquired on a subset of participants at the final two time points to estimate changes in global mean fractional anisotropy (FA). Linear mixed models were performed to estimate the change in eveningness over time. A series of linear regression models assessed the influence of change in eveningness on psychopathology and white matter development at age 19.
Results
Across the sample, a preference for eveningness became more predominant by 19 years of age. Greater individual‐level change towards eveningness significantly predicted greater severity in externalizing, but not internalizing, symptoms at 19 years of age. In contrast, change in psychopathology from 12 to 19 years of age was not associated with morning–eveningness at age 19. A change towards eveningness predicted an attenuated increase in FA between 17 and 19 years of age.
Conclusions
This study suggests that developmental changes in morning–evening preference may predict both neurodevelopmental and psychological outcomes in adolescents.
... When it comes to white matter (WM), the most-used method is diffusion tensor imaging (DTI) analysis that studies the structural changes of WM. A previous DTI study suggested that WM also plays an important role in maintaining circadian rhythm and reported alterations in the frontal and temporal lobe of WM and cingulate gyrus and corpus callosum following sleep deprivation (Rosenberg et al., 2014). Although DTI studies can reveal the details of WM structure, they cannot provide direct evidence of its function in vivo. ...
... The function of the cingulate has been reported to be disrupted in participants with both sleep disorders (Tomasi et al., 2009) and mood disorders (Amir et al., 2005;Wang et al., 2017). Furthermore, a DTI study of participants categorized as early (EC), late (LC), or intermediate (IC) chronotypes, where ECs tend to wake up early in the morning and find it difficult to remain awake beyond their usual bedtime, and LCs go to bed late and have difficulty getting up, revealed decreased WM fractional anisotropy of cingulate gyrus in participants with the LC chronotype (Rosenberg et al., 2014) who have symptoms such as sleep disturbance and vulnerability to Figure 4: Static FC and dynamic FC between WM networks. The static FC revealed that a significant reduction had occurred in the FC between the cingulate network (WM7) and occipital network (WM1), inferior longitudinal fasciculus network (WM2), precentral/postcentral network (WM3), brainstem network (WM5), corona radiate network (WM12), and orbitofrontal and inferior temporal network (WM13), and between the precentral/postcentral network (WM3) and cerebellum network (WM4) during jet lag. ...
... The difference in five connectivity states identified for the dynamic FC of the WM networks is displayed, and significant reduction was found between the cingulate network (WM7) and other WM networks. depression that are also associated with jet lag (Rosenberg et al., 2014). On the contrary, participants with sleep deprivation were reported to show increased FC (Liu et al., 2018) and increased FC density (Sterpenich et al., 2017) in pre-and postcentral regions bilaterally and which was suggested to reflect a compensatory mechanism (Huang et al., 2012). ...
Background
A long-haul flight across more than five time zones may produce a circadian rhythm sleep disorder known as jet lag. Little is known about the effect of jet lag on white matter (WM) functional connectivity (FC).
Objective
The present study is to investigate changes in WM FC in subjects due to recovery from jet lag after flying across six time zones.
Methods
Here, resting-state functional magnetic resonance imaging was performed in 23 participants within 24 hours of flying and again 50 days later. Gray matter (GM) and WM networks were identified by k-means clustering. WM FC and functional covariance connectivity (FCC) were analyzed. Next, a sliding window method was used to establish dynamic WM FC. WM static and dynamic FC and FCC were compared between when participants had initially completed their journey and 50 days later. Emotion was assessed using the Positive and Negative Affect Schedule and the State Anxiety Inventory.
Results
All participants were confirmed to have jet lag symptoms by the Columbian Jet Lag Scale. The static FC strengthes of cingulate network (WM7)- sensorimotor network and ventral frontal network- visual network were lower after the long-haul flight compared with recovery. Corresponding results were obtained for the dynamic FC analysis. The analysis of FCC revealed weakened connections between the WM7 and several other brain networks, especially the precentral/postcentral network. Moreover, a negative correlation was found between emotion scores and the FC between the WM7 and sensorimotor related regions.
Conclusions
The results of this study provide further evidence for the existence of WM networks and show that jet lag is associated with alterations in static and dynamic WM FC and FCC, especially in sensorimotor networks. Jet lag is a complex problem that not only is related to sleep rhythm but also influences emotion.
... Electronic copy available at: https://ssrn.com/abstract=3562443 6 matter also plays an important role in maintaining circadian rhythm is supported by a Diffusion Tensor Imaging (DTI) study which reported alterations in frontal and temporal lobe WM and in cingulate gyrus and corpus callosum following sleep deprivation 13 . Also of note is that corticospinal track injury can produce circadian rhythm-related disruptions of the H-reflex 14 . ...
... p < 0.008, FDR correct) during Jet Lag. No significant correlations were observed for negative emotion, anxiety or sleepiness score. of cingulate gyrus in subjects with the LC chronotype 13 who have symptoms such as sleep disturbance and vulnerability to depression that are also associated with Jet Lag 13 . On the contrary subjects with sleep deprivation were reported to show increased FC 40 and increased FC density [35] in pre-and post-central regions bilaterally and which was suggested to reflect a compensatory mechanism 41 There are several limitations that need to be considered. ...
... p < 0.008, FDR correct) during Jet Lag. No significant correlations were observed for negative emotion, anxiety or sleepiness score. of cingulate gyrus in subjects with the LC chronotype 13 who have symptoms such as sleep disturbance and vulnerability to depression that are also associated with Jet Lag 13 . On the contrary subjects with sleep deprivation were reported to show increased FC 40 and increased FC density [35] in pre-and post-central regions bilaterally and which was suggested to reflect a compensatory mechanism 41 There are several limitations that need to be considered. ...
... Studies have detected differences in measures of WM integrity (Rosenberg, Maximov, Reske, Grinberg, & Shah, 2014) and cortical volume (Rosenberg, Jacobs, Maximov, Reske, & Shah, 2018) between individuals of differing chronotypes. There has also been established sex differences in the human circadian rhythm (Wever, 1984), with women having circadian rhythms of melatonin and body temperature set to an earlier hour than men. ...
... Due to the observed differences in WM microstructure depending on chronotype (Rosenberg et al., 2018(Rosenberg et al., , 2014, the current study addressed the effect of chronotype on TOD effects by testing if there were any differences in TOD effects between differing chronotypes in the current sample. While we did find differing associations with other sleep-wake-characteristics between chronotypes, we did not find any significant effect of chronotype on TOD effects in the diffusion data. ...
... This lack of chronotypespecific effects can be reconciled with the previously observed effects due to differences in experimental setup. The current study used a within-subject longitudinal setup, while Rosenberg and colleagues (Rosenberg et al., 2014) relied on a cross-sectional design. ...
Recently, several magnetic resonance imaging (MRI) studies have reported time-of-day effects on brain structure and function. Due to the possibility that time-of-day effects reflect mechanisms of circadian regulation, the aim of this prospective study was to assess these effects while under strict experimental control of variables that might influence biological clocks, such as caffeine intake and exposure to blue-emitting light. In addition, the current study assessed whether time-of-day effects were driven by changes to extracellular space, by including estimations of non-Gaussian diffusion metrics obtained from diffusion kurtosis imaging, white matter tract integrity and the spherical mean technique, in addition to conventional diffusion tensor imaging -derived parameters. Participants were 47 healthy adults who underwent diffusion-weighted imaging in the morning and evening of the same day. Morning and evening scans were compared using voxel-wise tract based spatial statistics and permutation testing. A day of wakefulness was associated with widespread increases in fractional anisotropy, indices of kurtosis and indices of the axonal water fraction. In addition, wakefulness was associated with widespread decreases in radial diffusivity, both in the single compartment and in extra-axonal space. These results suggest that an increase in the intra-axonal space relative to the extra-axonal volume underlies time-of-day effects in human white matter, which is in line with activity-induced reductions to the extracellular volume. These findings provide important insight into possible mechanisms driving time-of-day effects in MRI.
... Our physiological measures were based on the motor system and indirect measures of the involved neurotransmitters, yet they suggest systematic effects of chronotype at the whole-brain level. Interestingly, chronotype-specific individual differences in brain anatomy (e.g., grey matter volume) have been described by some studies 64 , which could affect tDCS-induced neuroplasticity induction either in a facilitatory or inhibitory way. It is unlikely that differences in brain structure were the driving force of the results because both groups showed enhanced plasticity at specific times of the day congruent with their respective chronotype. ...
... Each question has a score and the sum scores range from 16 to 86, with scores below 42 indicating evening type or late chronotype (LC), and scores higher than 58 indicating morning type or early chronotype (EC). Definite evening (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), moderate evening (31-41), intermediate or neutral (42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58), moderate morning (59)(60)(61)(62)(63)(64)(65)(66)(67)(68)(69), and definite morning (70)(71)(72)(73)(74)(75)(76)(77)(78)(79)(80)(81)(82)(83)(84)(85)(86) are the five chronotype categories identified by the MEQ. The questionnaire shows high reported reliability and has a significant correlation with circadian rhythm-related hormonal changes, including melatonin 68 . ...
Circadian rhythms have natural relative variations among humans known as chronotype. Chronotype or being a morning or evening person, has a specific physiological, behavioural, and also genetic manifestation. Whether and how chronotype modulates human brain physiology and cognition is, however, not well understood. Here we examine how cortical excitability, neuroplasticity, and cognition are associated with chronotype in early and late chronotype individuals. We monitor motor cortical excitability, brain stimulation-induced neuroplasticity, and examine motor learning and cognitive functions at circadian-preferred and non-preferred times of day in 32 individuals. Motor learning and cognitive performance (working memory, and attention) along with their electrophysiological components are significantly enhanced at the circadian-preferred, compared to the non-preferred time. This outperformance is associated with enhanced cortical excitability (prominent cortical facilitation , diminished cortical inhibition), and long-term potentiation/depression-like plasticity. Our data show convergent findings of how chronotype can modulate human brain functions from basic physiological mechanisms to behaviour and higher-order cognition.
... Genome-wide association studies (GWAS) of neuroimaging measures have uncovered 213 independent significant genetic variants associated with 90 DTI parameters (Zhao et al., 2019) and 351 loci with chronotype (Jones et al., 2019). Also, neuroimaging studies have identified white matter differences in evening people (Rosenberg et al., 2014). Studies investigating the disruption of circadian cycles show that a day of wakefulness is associated with increases in white matter FA due to RD reductions (Elvsåshagen et al., 2015;Voldsbekk et al., 2020), thus suggesting that wakefulness-related effects may regulate white matter (Voldsbekk et al., 2020). ...
... chronotype is associated with higher average MD, AD and RD for all tracts, but with tract-specific distributions for each DTI parameter. Our results are highly consistent with previous findings describing white matter microstructural differences in several brain regions, including the corpus callosum, corona radiata, internal capsule and frontal and temporal lobes, when comparing evening to morning and intermediate chronotypes (Rosenberg et al., 2014). We identified genetic correlations between an evening chronotype and MD in the entire corpus callosum and corona radiata, as with the posterior segments of the internal capsule. ...
Several neuroimaging studies have reported associations between brain white matter microstructure and chronotype. However, it is unclear whether those phenotypic relationships are causal or underlined by genetic factors. In the present study, we use genetic data to examine the genetic overlap and infer causal relationships between chronotype and diffusion tensor imaging (DTI) measures. We identify 29 significant pairwise genetic correlations, of which 13 also show evidence for a causal association. Genetic correlations were identified between chronotype and brain-wide mean, axial and radial diffusivities. When exploring individual tracts, 10 genetic correlations were observed with mean diffusivity, 10 with axial diffusivity, 4 with radial diffusivity and 2 with mode of anisotropy. We found evidence for a possible causal association of eveningness with white matter microstructure measures in individual tracts including the posterior limb and the retrolenticular part of the internal capsule; the genu and splenium of the corpus callosum and the posterior, superior and anterior regions of the corona radiata. Our findings contribute to the understanding of how genes influence circadian preference and brain white matter and provide a new avenue for investigating the role of chronotype in health and disease.
... The structural determinants underlying chronotype differences are not yet well-understood because brainimaging studies operating on chronotypes are still quite sparse. To date, only one structural study has examined the white matter (WM) integrity of chronotype differences (Rosenberg et al. 2014) and reported WM differences in frontal and temporal lobes, cingulate gyrus and corpus callosum. Concerning grey matter density, a study by Takeuchi et al. (2015) reported lower regional grey matter density in the left posterior parietal cortex and adjacent areas, and in the precuneus and adjacent areas in morningness [as assessed by the Morningness-Eveningness Questionnaire (MEQ, Horne and Östberg 1976)] as compared to eveningness. ...
... A previous study of our own group examined the white matter integrity of chronotype differences (Rosenberg et al. 2014): tract-based spatial statistics performed on diffusion tensor imaging (DTI) data highlight that LCs were characterised by less diffusivity in WM in the frontal and temporal lobes, the cingulate gyrus, and the corpus callosum. Interestingly, it has been postulated that neurons can compensate for a loss of local connectivity in white matter with greater neural synaptic responsiveness (Barulli and Stern 2013;Lighthall et al. 2014;Daselaar et al. 2015). ...
Based on individual circadian cycles and associated cognitive rhythms, humans can be classified via standardised self-reports as being early (EC), late (LC) and intermediate (IC) chronotypes. Alterations in neural cortical structure underlying these chronotype differences have rarely been investigated and are the scope of this study. 16 healthy male ECs, 16 ICs and 16 LCs were measured with a 3 T MAGNETOM TIM TRIO (Siemens, Erlangen) scanner using a magnetization prepared rapid gradient echo sequence. Data were analysed by applying voxel-based morphometry (VBM) and vertex-wise cortical thickness (CTh) analysis. VBM analysis revealed that ECs showed significantly lower grey matter volumes bilateral in the lateral occipital cortex and the precuneus as compared to LCs, and in the right lingual gyrus, occipital fusiform gyrus and the occipital pole as compared to ICs. CTh findings showed lower grey matter volumes for ECs in the left anterior insula, precuneus, inferior parietal cortex, and right pars triangularis than for LCs, and in the right superior parietal gyrus than for ICs. These findings reveal that chronotype differences are associated with specific neural substrates of cortical thickness, surface areas, and folding. We conclude that this might be the basis for chronotype differences in behaviour and brain function. Furthermore, our results speak for the necessity of considering “chronotype” as a potentially modulating factor in all kinds of structural brain-imaging experiments.
... In a large voxelbased morphometry study Takeuchi and colleagues (2015) observed increased grey matter density in posterior parietal cortex and precuneus and reduced grey matter density in orbitofrontal regions (Takeuchi et al., 2015). Using Diffusion Tensor Imaging (DTI) Rosenberg et al., reported significantly lower fractional anisotropy ( a measure of microstructural integrity) in the white matter underlying the left anterior cingulate cortex (ACC) and corpus callosum in evening-type healthy males free of current or previous psychiatric disorder (Rosenberg et al., 2014). Notably, white matter underlying the ACC and corpus callosum are reportedly affected by depression (Kempton et al., 2011;Matsuoka et al., 2017;Repple et al., 2017) and risk for depression (Huang et al., 2012). ...
... Notably, white matter underlying the ACC and corpus callosum are reportedly affected by depression (Kempton et al., 2011;Matsuoka et al., 2017;Repple et al., 2017) and risk for depression (Huang et al., 2012). Together, these data (Antypa et al., 2017;Berdynaj et al., 2016;Watts and Norbury, 2017) demonstrate that eveningness is associated with a number of cognitive and physiological vulnerabilities and altered structural integrity (Rosenberg et al., 2014;Takeuchi et al., 2015) which may confer risk for future depression. ...
Increasing evidence suggests that eveningness is associated with increased risk for depression. Eveningness, however, is also associated with poor sleep quality and the unique role of eveningness in depressive symptomatology remains to be elucidated. The goal of the current study, therefore, was to examine the inter-relationships between eveningness, subjective sleep quality and depressive symptoms in healthy participants free of current or previous depression and sleep disorder. Here, 167 healthy participants (mean age 24.16, 129/38 females/males) completed the reduced Morningness–Eveningness Questionnaire (rMEQ), the Pittsburgh Sleep Quality Index (PSQI) and the Centre for Epidemiological Studies Depression Scale (CES-D). Bootstrap mediation analysis for a simple mediation model including rMEQ, PSQI and CES-D was applied. Eveningness was associated with increased depressive symptoms and mediation analysis showed that this relationship was partly mediated by sleep quality. Our results suggest that indicators of depression observed in evening-type individuals cannot be attributed exclusively to disturbed sleep. We suggest that interventions that target both sleep quality and dysfunctional cognitive styles would be optimal to promote well-being in evening-type individuals.
... Individuals with eveningness preference showed alterations in the structure and metabolism of a neural circuitry that was critical for accurate affective responses and emotional regulation (Hasler et al., 2012;Kuperczkó et al., 2015;Rosenberg, Maximov, Reske, Grinberg, & Shah, 2014). As the relationship between eveningness and emotional dysregulation seems to be at least partly mediated by sleep complaints (Levandovski et al., 2011;Rosenberg et al., 2014;Simor, Zavecz, et al., 2015), treatments focusing on circadian rhythms and sleep quality might be beneficial for patients with OCD. ...
... Individuals with eveningness preference showed alterations in the structure and metabolism of a neural circuitry that was critical for accurate affective responses and emotional regulation (Hasler et al., 2012;Kuperczkó et al., 2015;Rosenberg, Maximov, Reske, Grinberg, & Shah, 2014). As the relationship between eveningness and emotional dysregulation seems to be at least partly mediated by sleep complaints (Levandovski et al., 2011;Rosenberg et al., 2014;Simor, Zavecz, et al., 2015), treatments focusing on circadian rhythms and sleep quality might be beneficial for patients with OCD. In fact, pharmacological and behavioral interventions aiming to normalize circadian rhythms showed promising outcomes in case studies of OCD patients (Coles & Sharkey, 2011;Fornaro, 2011). ...
Background
Obsessive–compulsive disorder (OCD) is characterized by intrusive thoughts and repetitive behaviors that severely encumber daily functioning. OCD patients seem to exhibit sleep disturbances, especially delayed bedtimes that reflect disrupted circadian rhythmicity. Morningness–eveningness is a fundamental factor reflecting individual variations in diurnal preferences related to sleep and waking activities. Eveningness reflecting a delayed sleep–wake timing has repeatedly been associated with sleep problems and negative affect (NA). Therefore, the aim of this study was to examine the associations between morningness–eveningness, sleep complaints, and symptom severity in OCD patients and compared with a mixed psychiatric control group.
Materials and methods
The data of 49 OCD and 49 mixed psychiatric inpatients (with unipolar depression and anxiety disorders) were analyzed. Patients completed questionnaires regarding morningness–eveningness, sleep quality, nightmare frequency, depression, anxiety, and affective states. Obsessive and compulsive symptom severity was also assessed within the OCD group by clinician-rated scales.
Results
Eveningness preference was associated with impaired sleep quality and higher NA in OCD patients. In addition, impaired sleep quality showed a moderate correlation with anxiety and strong correlations with depressive symptoms and NA. Interestingly, in the mixed psychiatric group, eveningness was not linked to NA, and sleep quality also showed weaker associations with depressive symptoms and NA. Within the OCD group, eveningness preference was predictive of poorer sleep quality regardless the influence of depressive symptoms.
Conclusion
Our findings suggest that eveningness and sleep complaints are predictive of affective dysfunctions, and should be carefully considered in the evaluation and treatment of OCD patients.
... Work by Jones et al. (1999) suggested an evolutionary advantage to circadian rhythms because they prepare the body for the transition from night to day; their research also supported a growing body of evidence indicating that sleep-wake cycles-one of many diurnal or circadian processes-are largely heritable and consistent throughout adulthood in mammals (Rosenberg, Maximov, Reske, Grinberg & Shah, 2014). While all circadian rhythms for all mammals are aligned with (entrained to) the light-dark cycles of the earth's rotation (Buhr & Takahashi, 2013), variation exists at the individual level ( Duffy et al., 2001). ...
... One of the difficulties found with wake times that are too early (in reference to natural circadian rhythms) is that they may be too close to the circadian low point. This nadir is where a cycle of deep or slow-wave sleep (SWS) occurs-the most restorative of the sleep stages-when activation hormones such as cortisol are also at their lowest, and deactivation chemicals such as adenosine are at their highest (Bailey & Heitkemper, 2001;Rosenberg et al., 2014). People attempt to offset high adenosine levels to increase alertness levels when they are tired by consuming caffeine, which acts as an adenosine-receptor antagonist (Hewlett & Smith, 2007). ...
This study examined the relationship of employees’ natural sleep-wake cycles (chronotypes) and work-start times with self-reports of performance, job satisfaction, and absenteeism, and the mediating role of sleep deprivation in this relationship. Prior research demonstrated that natural sleep-wake cycles were often misaligned with social schedules (circadian desynchrony), leading to decrements in performance, satisfaction, and attendance. This study utilized moderated multiple regression to test the predictions that: (1) chronotype and early work-start times interact to affect job satisfaction and performance such that the relationship would be negative for early work-start times, then positive as start times got later; (2) chronotype and early work-start times interact to affect absenteeism such that the relationship would be positive for early work-start times, then negative as start times got later; and, (3) there is a partial mediating effect of sleep deprivation on these relationships. The study sample consisted of 463 participants working full time in daytime white-collar positions. Participants completed online the Morningness-Eveningness Questionnaire (Horne & Ostberg, 1976), the Human Performance Questionnaire-Subscale (World Health Organization, 2001), the Reduced-Item Scale of Affective Job Satisfaction from the Brayfield-Rothe Index (1951), the Stanford Sleepiness Scale (Hoddes et al., 1973), and items measuring sleep deprivation. The predicted interaction of chronotype and early work-start time was not found. Results indicated that higher scores on the MEQ (indicating morningness) were significantly associated with earlier work-start times (r = -.25), higher job satisfaction scores (r = .25), and more sleep hours (r = .10). Later work-start times were significantly associated with lower performance scores (r = -.11), and fewer sleep hours (r = .12). The number of sleep hours was associated with higher performance scores (r = .18), higher job satisfaction scores (r = .19), and fewer absences (r = -.25). An examination of the relationships among these variables can broaden the understanding of employee health-related factors in the workplace.
... Several structural brain-imaging studies have emphasized grey matter volume (GMV) differences between chronotypes in the precuneus, posterior parietal cortex, orbitofrontal cortex, basal ganglia and hippocampus, which link chronotype to social behaviour and mood disorder [27][28][29][30] . A diffusion magnetic resonance imaging (MRI) study emphasized white-matter differences in the frontal and temporal lobes, cingulate gyrus and corpus callosum between the chronotypes, perhaps explaining the vulnerability of the late chronotype to depression and substance use 31 . Furthermore, functional brain-imaging studies highlighted the different roles that the attentional, emotional and reward brain networks play in different chronotypes [32][33][34] . ...
The rapid shifts in society have altered human behavioural patterns, with increased evening activities, increased screen time and changed sleep schedules. As an explicit manifestation of circadian rhythms, chronotype is closely intertwined with physical and mental health. Night owls often exhibit unhealthier lifestyle habits, are more susceptible to mood disorders and have poorer physical fitness compared with early risers. Although individual differences in chronotype yield varying consequences, their neurobiological underpinnings remain elusive. Here we conducted a pattern-learning analysis with three brain-imaging modalities (grey matter volume, white-matter integrity and functional connectivity) and capitalized on 976 phenotypes in 27,030 UK Biobank participants. The resulting multilevel analysis reveals convergence on the basal ganglia, limbic system, hippocampus and cerebellum. The pattern derived from modelling actigraphy wearables data of daily movement further highlighted these key brain features. Overall, our population-level study comprehensively investigates chronotype, emphasizing its close connections with habit formation, reward processing and emotional regulation.
... In addition to neural noise, chronotype-defined as an individual's preference for "morningness" or "eveningness"-55 serves as a key modulator of cognitive performance under sleep deprivation (Facer-Childs et al., 2018; Matchock and 56 Toby Mordkoff, 2009;Rosenberg et al., 2014;Taillard et al., 2003). Chronotype influences not only baseline levels 57 of alertness but also shapes diurnal performance trajectories and vulnerability to cognitive decline with prolonged 58 wakefulness (Van Dongen et al., 2003). ...
Cognitive performance during sleep deprivation shows significant individual differences, with some displaying remarkable resilience. This study explores the role of stochastic resonance—where moderate noise enhances system performance—in attention network functioning during sleep deprivation. We developed a computational model simulating three interacting neural networks (Default Mode Network, Salience Network, and Executive Control Network) under varying levels of sleep deprivation and background neural noise. Results demonstrate an emergent, nonlinear relationship between noise and attentional performance, with moderate noise facilitating faster network switching and response times across all sleep deprivation conditions. The most beneficial range of noise intensity shifted with increasing sleep deprivation, suggesting a potential compensatory mechanism. Individual differences in chronotype modulated these effects, with morning chronotypes showing greater vulnerability to sleep deprivation but more substantial benefits from effective noise. These findings offer a novel theoretical framework for understanding cognitive resilience during sleep loss and suggest that individually-calibrated noise stimulation could counteract sleep deprivation effects in operational settings.
... Changes in white matter integrity have consistently been associated with different sleep traits, for example, insomnia (Bresser et al. 2020;Grau-Rivera et al. 2020;Kang et al. 2018;Li et al. 2016;Spiegelhalder et al. 2014), short sleep duration (Grumbach et al. 2020;Khalsa et al. 2017;Kocevska et al. 2019;Takeuchi et al. 2018;Yaffe et al. 2016), late chronotype (Rosenberg et al. 2014) and daytime sleepiness (Chondrogiorgi et al. 2016;Koller et al. 2020;Matsui et al. 2006). These changes usually involve reduced fractional anisotropy or altered radial, axial or mean diffusivity throughout the whole brain. ...
Many people experience impaired sleep health, yet knowledge about its neurobiological correlates is limited. As previous studies have found associations between white matter integrity and several sleep traits, white matter integrity could be causally implicated in poor sleep health. However, these studies were often limited by small sample sizes. In this study, we examine associations between multiple indices of white matter integrity and sleep health in 29,114 UK Biobank participants. Late chronotype, daytime sleepiness, insomnia symptoms and, most extensively, long sleep duration were independently associated with diffusion MRI markers of reduced white matter integrity. Previous findings showing an association between insomnia symptoms and decreased fractional anisotropy (FA) in the anterior internal capsule could not be replicated. To our knowledge, the current analysis is the first study to find an association between long sleep duration and impaired microstructural white matter integrity. Previous assumptions concerning the role of white matter integrity for insomnia are challenged.
... En de zomertijd, die de sociale jetlag van avondmensen met een uur verlengt en twee keer per jaar iedereen een kleine jetlag bezorgt als de klok wordt verzet, kan beter worden afgeschaft. 18,27 Figuur 4 | Het effect van ochtend-en avondtraining bij personen met een relatief vroeg of laat chronotype. Voor verklaring zie tekst (bewerkt naar Thomas et al. 25 ). ...
Dit is het laatste van een drietal artikelen over het verband tussen fysiek prestatievermogen en het 24-uursritme van ons lichaam. In dit artikel gaat het over de vraag op welk moment van de dag je het beste kunt gaan trainen om gezond(er) te worden en te blijven.
... Based on the results of available studies, for example Zerbini & Merrow [49], and Rosenberg et al. [50], we have formulated the following hypotheses: ...
The presented paper deals with the symbolism of colors, i.e., color associations. The aim of the paper is to verify the correlation of colors and their symbolism. The combination of color and its meaning was based on the existence of a physiological variable, namely the psychophysiological state. The diurnal preference of individuals was used for this purpose, which divided the subjects according to the chronotype into morning and evening groups. From this starting point, the color preferences of the examined people were monitored in the final phase by means of a color evaluation test. The theoretical part of the paper provides a theoretical framework and starting points for research. The research part describes in detail the research process, especially the methods used. The research itself was attended by 720 people aged 20–40 years. As research methods were used: the Composite scale of morningness, Bourdon's performance test, the Subjective scale of activation, and the Color evaluation test. The respondents had the task of associating colors with their current psychophysiological state. The established hypotheses were mostly confirmed. From a broader point of view, we have come to the conclusion that people attribute certain properties to individual colors, so there is psychic content belonging to individual colors. The colors expressing activity included yellow, orange, and red, and respondents from the group of evening chronotypes also included blue. Calm colors include blue, green, and gray. The most indifferent color was purple. The obtained results were statistically significant. There were also relatively strong correlations in the evaluation of colors due to the psychological focus of the research. Other stimuli for research were also found in the research. Doi: 10.28991/ESJ-2022-06-04-010 Full Text: PDF
... Interestingly, chronotype-specific individual differences in brain anatomy (e.g. grey matter volume) have been described by some studies 61 , which could affect tDCS-induced neuroplasticity . CC-BY 4.0 International license available under a was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. ...
Circadian rhythms have natural relative variations among humans known as chronotype. Chronotype or being a morning or evening person, has a specific physiological, behavioural, and also genetic manifestation. Whether and how chronotype modulates human brain physiology and cognition is, however, not well understood. Here we examined how chronotype affects cortical excitability, neuroplasticity, and cognition in early and late chronotype individuals. We monitored motor cortical excitability, brain stimulation-induced neuroplasticity, and examined motor learning and cognitive functions at circadian-preferred and non-preferred times of day in 32 individuals. Motor learning and cognitive performance (working memory, and attention) along with their electrophysiological components were significantly enhanced at the circadian-preferred, compared to the non-preferred time. This outperformance was associated with enhanced cortical excitability (prominent cortical facilitation, diminished cortical inhibition), and long-term potentiation/depression-like plasticity. Our data show convergent findings of the impact of chronotype on human brain functions from basic physiological mechanisms to behaviour and higher cognitive functions.
... However, the question of whether chronotype is associated with features of brain structure has received relatively less attention. One study performed on young males (Rosenberg et al. 2014) reported evidence of lower white matter integrity in specific fiber tracts of late chronotypes, with chronotype defined categorically by the MCTQ. Other studies have examined the effects on brain volume. ...
Chronotype or diurnal preference is a questionnaire-based measure influenced both by circadian period and by the sleep homeostat. In order to further characterize the biological determinants of these measures, we used a hypothesis-free approach to investigate the association between the score of the morningness-eveningness questionnaire (MEQ) and the Munich chronotype questionnaire (MCTQ), as continuous variables, and volumetric measures of brain regions acquired by magnetic resonance imaging (MRI). Data were collected from the Baependi Heart Study cohort, based in a rural town in SouthEastern Brazil. MEQ and anatomical 1.5-T MRI scan data were available from 410 individuals, and MCTQ scores were available from a subset of 198 of them. The average MEQ (62.2 ± 10.6) and MCTQ (average MSFsc 201 ± 85 min) scores were suggestive of a previously reported strong general tendency toward morningness in this community. Setting the significance threshold at P > .002 to account for multiple comparisons, we observed a significant association between lower MEQ score (eveningness) and greater volume of the left anterior occipital sulcus (β = −0.163, p = .001) of the occipital lobe. No significant associations were observed for MCTQ. This may reflect the smaller dataset for MCTQ, and/or the fact that MEQ, which asks questions about preferred timings, is more trait-like than the MCTQ, which asks questions about actual timings. The association between MEQ and a brain region dedicated to visual information processing is suggestive of the increasingly recognized fluidity in the interaction between visual and nonvisual photoreception and the circadian system, and the possibility that chronotype includes an element of masking.
... A stronger relationship between the post-and difference scores of the "sleep" factors (energy-sleep and sleep-sex) and the sum score can also be observed for the BDI. Furthermore, bidirectional relationships involving functional and structural connectivity between sleep disorders and MDD are known (Rosenberg et al., 2014;Khazaie et al., 2017). This all suggests a more complex relationship between SSRIs, sleep, and treatment response that demands further investigation. ...
Introduction: The early and therapy-specific prediction of treatment success in major depressive disorder is of paramount importance due to high lifetime prevalence, and heterogeneity of response to standard medication and symptom expression. Hence, this study assessed the predictability of long-term antidepressant effects of escitalopram based on the short-term influence of citalopram on functional connectivity. Methods: Twenty nine subjects suffering from major depression were scanned twice with resting-state functional magnetic resonance imaging under the influence of intravenous citalopram and placebo in a randomized, double-blinded cross-over fashion. Symptom factors were identified for the Hamilton depression rating scale (HAM-D) and Beck's depression inventory (BDI) taken before and after a median of seven weeks of escitalopram therapy. Predictors were calculated from whole-brain functional connectivity, fed into robust regression models, and cross-validated. Results: Significant predictive power could be demonstrated for one HAM-D factor describing insomnia and the total score (r = 0.45–0.55). Remission and response could furthermore be predicted with an area under the receiver operating characteristic curve of 0.73 and 0.68, respectively. Functional regions with high influence on the predictor were located especially in the ventral attention, fronto-parietal, and default mode networks. Conclusion: It was shown that medication-specific antidepressant symptom improvements can be predicted using functional connectivity measured during acute pharmacological challenge as an easily assessable imaging marker. The regions with high influence have previously been related to major depression as well as the response to selective serotonin reuptake inhibitors, corroborating the advantages of the current approach of focusing on treatment-specific symptom improvements.
... To date only three studies have used whole-brain, voxel-wise measures to examine the structural determinants of circadian typology. Rosenberg and colleagues investigated the impact of chronotype on anatomical connectivity using Diffusion Tensor Imaging (DTI) in a population of 59 18-35 year old males [27]. Compared to early chronotypes, late types had reduced microstructural integrity (lower fractional anisotropy values) in white matter underlying the cingulate gyrus and frontal lobe and greater mean diffusivity (which may reflect localised reductions in neuropil) in frontal regions and precentral gyrus. ...
Eveningness (a diurnal preference for evening time) is associated with a number of negative health outcomes and risk and prevalence for psychiatric disorder. Our understanding of the anatomical substrates of diurnal preference, however, is limited. The current study used Voxel-Based Morphometry to compare grey matter volume in a large sample (N = 3730) of healthy adults determined by questionnaire to be either definite morning-type or definite evening-type. Eveningness was associated with increased grey matter volume in precuneus, brain regions implicated in risk and reward processing (bilateral nucleus accumbens, caudate, putamen and thalamus) and orbitofrontal cortex. These results indicate an anatomical-basis for diurnal preference which may underlie reported differences in behaviour and brain function observed in these individuals.
... Sleep deprivation also leads to cognitive impairments (McEwen, 2006). Sleep deprivation has also been associated with increases in fighting behavior (de Paula & Hoshino, 2002), impaired physical, psychological, and emotional health, stress, increased cortisol levels, temporal lobe atrophy (Cho, 2001), chronic disease, elevated mortality risk (Carroll et al., 2016), senescence, accelerated aging (Carroll et al., 2016), structural changes to the brain, and cognitive impairment (Rosenberg, Maximov, Reske, Grinberg, & Shah, 2014). ...
We live in a surprisingly violent world. We experience physical assault, emotional and psychological attack, and even the intellectual violence of manipulation and indoctrination. Psychology is becoming increasingly aware not only of the prevalent violence, but also of the profoundly deleterious impact of said violence on the human mind and body; however, sociology lags behind. Socialization, or our experiences at the hands of agents of socialization, is a key concept in sociology. Every introductory sociology text that is printed devotes and entire chapter to a discussion of socialization and related concepts. However rarely, if at all, is there any indication that sociologists are aware of the profoundly deleterious impact of toxicity (violence, neglect, etc.) in the socialization process. This research note seeks to alleviate this lacuna by providing a concept, toxic socialization, by which sociologists and others (e.g., psychologists, parents, teachers, and anybody involved in the socialization of human beings) can more readily discuss the problem of a violence and neglect in our socialization processes.
... Chronotype-specificity refers to individual preferences in sleep and wakefulness that reflect endogenous, self-sustained genetic dispositions (Roenneberg & Merrow, 2016). Chronotypes have been found to be associated with differences in white matter integrity and gray matter density (Rosenberg, Maximov, Reske, Grinberg, & Shah, 2014;Takeuchi et al., 2015). Additionally, chronotype-specific cerebral responses to language processing and attention also have been found (Reske, Rosenberg, Plapp, Kellermann, & Shah, 2015;Rosenberg, Reske, Warbrick, & Shah, 2015). ...
Total sleep deprivation (TSD) is common in modern society leading to deterioration of multiple aspects of cognition. Dynamic interaction effect of circadian rhythmicity and homeostatic sleep pressure on sustained attention have been intensively investigated, while how this effect was represented on performance and cerebral responses to working memory, another important element of many neurobehavioral tasks, was not well elucidated. Thirty‐six healthy subjects with intermediate chronotype performed the Sternberg working‐memory task (SWMT) while undergoing functional magnetic resonance imaging every 2 hr from 10:00 p.m. on the first day to 6:00 a.m. on the second day. Using data from three imaging sessions (10:00 p.m., 04:00 a.m., and 06:00 a.m.), we found that the slowest SWMT reaction time and weakest cerebral responses were not at the end of TSD (06:00 a.m.) but during the early morning (04:00 a.m.) hours of the TSD. In addition, during this worst period of TSD, reaction time for the SWMT were found to be negatively correlated with task‐related activation in the angular gyrus and positively correlated with the degree of negative correlation between the control and default networks. Our results revealed a rebound of SWMT reaction time and cerebral responses after the mid‐time point of regular biological sleep night and provided more evidence that different cognitive tasks are differentially affected by sleep loss and circadian rhythmicity.
... This is the first time that such relationships have been observed in a large population-based sample with a standardised test battery, supporting a range of smaller studies reporting on academic achievement, salary and intelligence outcomes [39e42]. We note, however, that our findings are at odds with evidence from diffusion tensor imaging showing white matter deficits in frontal and temporal lobes, cingulate gyrus and corpus callosum in evening types [43]. Although we were unable to investigate the time of testing in relation to chronotype and performance, assessments were conducted during standard office hours and therefore would be expected to work against evening types, rather than account for superior performance. ...
... These changes of resting state connectivity are reversed by sleep (Kaufmann et al., 2016), and longer sleep duration associates with higher cortico-limbic connectivity (Killgore, Schwab, & Weiner, 2012). Moreover, chronotype associates with markers of white matter structure and grey matter function: extreme early and late chronotypes, compared to intermediate chronotypes, show attenuated dorsolateral prefrontal cortex (DLPFC) activation during an attention task (Reske, Rosenberg, Plapp, Kellermann, & Shah, 2015), and late chronotypes show reduced fractional anisotropy in ACC regions (Rosenberg, Maximov, Reske, Grinberg, & Shah, 2014). ...
Mood disorders are often characterised by alterations in circadian rhythms, sleep disturbances, and seasonal exacerbation. Conversely, chronobiological treatments utilise zeitgebers for circadian rhythms such as light to improve mood and stabilise sleep, and manipulations of sleep timing and duration as rapid antidepressant modalities. Although sleep deprivation (“wake therapy”) can act within hours, and its mood‐elevating effects be maintained by regular morning light administration /medication /earlier sleep, it has not entered the regular guidelines for treating affective disorders as a first‐line treatment. The hindrances to using chronotherapeutics may lie in their lack of patentability, few sponsors to carry out large multicentre trials, non‐reimbursement by medical insurance, and their perceived difficulty or exotic “alternative” nature. Future use can be promoted by new technology (single‐sample phase measurements, phone apps, movement and sleep trackers) that provides ambulatory documentation over long periods and feedback to therapist and patient. Light combinations with cognitive behavioural therapy and sleep hygiene practice may speed up and also maintain response. The urgent need for new antidepressants should hopefully lead to reconsideration and implementation of these non‐pharmacological methods, as well as further clinical trials.
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... We also found increased GMV in the striatum starting at the time point of 20 h SD, and these increased GMV remained into the later stage of the SD. Evidence also indicates that individuals with late chronotype who prefer to go to bed late in the evening had structural differences in the cingulate cortex and corpus callosum (68). In our SD study, we also found increased GMV in the corpus callosum and cingulate cortex. ...
Background: Insufficient sleep is common in daily life and can lead to cognitive impairment. Sleep disturbance also exists in neuropsychiatric diseases. However, whether and how acute and chronic sleep loss affect brain morphology remain largely unknown.
Methods: We used voxel-based morphology method to study the brain structural changes during sleep deprivation (SD) at six time points of rested wakefulness, 20, 24, 32, 36 h SD, and after one night sleep in 22 healthy subjects, and in 39 patients with chronic primary insomnia relative to 39 status-matched good sleepers. Attention network and spatial memory tests were performed at each SD time point in the SD Procedure. The longitudinal data were analyzed using one-way repeated measures ANOVA, and post-hoc analysis was used to determine the between-group differences.
Results: Acute SD is associated with widespread gray matter volume (GMV) changes in the thalamus, cerebellum, insula and parietal cortex. Insomnia is associated with increased GMV in temporal cortex, insula and cerebellum. Acute SD is associated with brain atrophy and as SD hours prolong more areas show reduced GMV, and after one night sleep the brain atrophy is restored and replaced by increased GMV in brain areas. SD has accumulative negative effects on attention and working memory.
Conclusions: Acute SD and insomnia exhibit distinct morphological changes of GMV. SD has accumulative negative effects on brain morphology and advanced cognitive function. The altered GMV may provide neurobiological basis for attention and memory impairments following sleep loss.
Statement of significance
Sleep is less frequently studied using imaging techniques than neurological and psychiatric disorders. Whether and how acute and chronic sleep loss affect brain morphology remain largely unknown. We used voxel-based morphology method to study brain structural changes in healthy subjects over multiple time points during sleep deprivation (SD) status and in patients with chronic insomnia. We found that prolonged acute SD together with one night sleep recovery exhibits accumulative atrophic effect and recovering plasticity on brain morphology, in line with behavioral changes on attentional tasks. Furthermore, acute SD and chronic insomnia exhibit distinct morphological changes of gray matter volume (GMV) but they also share overlapping GMV changes. The altered GMV may provide structural basis for attention and memory impairments following sleep loss.
... Besides differences in circadian phase (Kerkhof & Van Dongen, 1996;Mongrain et al., 2004), MT individuals differ from ET individuals by a faster buildup of homeostatic sleep pressure during wakefulness (Taillard et al., 2003) and by its faster dissipation during sleep (Mongrain et al., 2005(Mongrain et al., , 2006aSchmidt et al., 2009). Recently, concerns have increased regarding chronotype specificity in anatomical (Rosenberg et al., 2014;Takeuchi et al., 2015) and task-related neuroimaging studies Rosenberg et al., 2015;Schmidt et al., 2009). Moreover, task performance during a normal waking day is regulated through differential interactions between homeostatic and circadian processes. ...
... Besides differences in circadian phase (Kerkhof & Van Dongen, 1996;Mongrain et al., 2004), MT individuals differ from ET individuals by a faster buildup of homeostatic sleep pressure during wakefulness (Taillard et al., 2003) and by its faster dissipation during sleep (Mongrain et al., 2005(Mongrain et al., , 2006aSchmidt et al., 2009). Recently, concerns have increased regarding chronotype specificity in anatomical (Rosenberg et al., 2014;Takeuchi et al., 2015) and task-related neuroimaging studies Rosenberg et al., 2015;Schmidt et al., 2009). Moreover, task performance during a normal waking day is regulated through differential interactions between homeostatic and circadian processes. ...
Studies have elucidated the various modulatory effects of chronotype and time-of-day on task-dependent brain activity, but it is unclear how chronotype and time-of-day regulate brain activity in response inhibition tasks. To address this question, we used functional magnetic resonance imaging (fMRI) to explore the effects of chronotype and time-of-day on response inhibition in normal day-night conditions. Morning-type (MT) and evening-type (ET) participants conducted the stop-signal task in morning (08:00–12:00 hours) and evening (19:00–23:00 hours) sessions. The results showed that inhibition-related cerebral responses in the medial frontal gyrus (MFG), middle cingulate cortex (MCC), thalamus and other typical regions for the execution of response inhibition significantly decreased from morning to evening in MT participants, whereas activity in the right inferior frontal gyrus (IFG)/insula, MFG, MCC and thalamus remained stable or increased in ET participants. The chronotypical differences in homeostatic sleep pressure may explain the observed individual differences in maintaining cognition-related cortical activation. These results suggest the importance of considering chronotype and time-of-day in the design and analysis of cognitive neuroscience studies.
... This is the first time that such relationships have been observed in a large population-based sample with a standardised test battery, supporting a range of smaller studies reporting on academic achievement, salary and intelligence outcomes [39e42]. We note, however, that our findings are at odds with evidence from diffusion tensor imaging showing white matter deficits in frontal and temporal lobes, cingulate gyrus and corpus callosum in evening types [43]. Although we were unable to investigate the time of testing in relation to chronotype and performance, assessments were conducted during standard office hours and therefore would be expected to work against evening types, rather than account for superior performance. ...
Objective: The relationship between insomnia symptoms and cognitive performance is unclear, particularly at the population level. We conducted the largest examination of this association to date through analysis of the UK Biobank, a large population-based sample of adults aged 40-69 yrs. We also sought to determine associations between cognitive performance and self-reported chronotype, sleep medication use, and sleep duration.
Methods: This cross-sectional, population-based study involved 477,529 participants, comprising 133,314 with frequent insomnia symptoms (age: 57.4 ± 7.7 yrs; 62.1% female) and 344,215 controls without (age: 56.1 ± 8.2 yrs; 52.0% female). Cognitive performance was assessed through a touchscreen test battery probing reasoning, basic reaction time, numeric memory, visual memory and prospective memory. Adjusted models included relevant demographic, clinical and sleep variables.
Results: Frequent insomnia symptoms were associated with cognitive impairment in unadjusted models, however these effects were reversed after full adjustment, leaving those with frequent insomnia symptoms showing statistically better cognitive performance over those without. Relative to intermediate chronotype, evening chronotype was associated with superior task performance, while morning chronotype was associated with the poorest performance. Sleep medication use and both long (>9hrs) and short (<7hrs) sleep duration were associated with impaired performance.
Conclusions: Our results suggest that after adjustment for potential confounding variables, frequent insomnia symptoms may be associated with a small statistical advantage, which is unlikely to be clinically meaningful, on simple neurocognitive tasks. Further work is required to examine mechanistic underpinnings of an apparent evening chronotype advantage in cognitive performance, as well as impairment associated with morning chronotype, sleep medication use, and sleep duration extremes.
... Moreover, often patients suffering from depression show related disorders, which were not controlled for here. For example, depression is often accompanied by alterations in sleep patterns, which are also related to WM integrity [Rosenberg et al., 2014]. Additionally, as this is a crosssectional study, we have only demonstrated a correlation between DTI metrics and depression, but cannot infer which occurred first. ...
Diffusion tensor imaging (DTI) has often been used to examine white matter (WM) tract abnormalities in depressed subjects, but these studies have yielded inconsistent results, probably, due to gender composition or small sample size. In this study, we applied different analysis pipelines to a relatively large sample of individuals with depression to determine whether previous findings in depression can be replicated with these pipelines. We used a "standard" DTI algorithm and maps computed through a free-water (FW) corrected DTI. This latter algorithm is able to identify and separate the effects of extracellular FW on DTI metrics. Additionally, skeletonized and WM voxel-based analysis (VBA) methods were used. Using the skeletonized method, DTI maps showed lower fractional anisotropy (FA) in depressed subjects in the left brain hemisphere, including the anterior thalamic radiation (ATR L), cortical spinal tract (CST L), inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, and superior longitudinal fasciculus (SLF L). Differences in radial diffusivity (RD) were also found. For the VBA using RD, we found different results when we used FW uncorrected and corrected DTI metrics. Relative to the VBA approach, the skeletonized analysis was able to identify more clusters where WM integrity was altered in depressed individuals. Different significant correlations were found between RD and the Patient Health Questionnaire in the CST L, and SLF L. In conclusion, the skeletonized method revealed more clusters than the VBA and individuals with depression showed multiple WM abnormalities, some of which were correlated with disease severity Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.
... Although there is a scarcity of longitudinal brain DTI studies during the sleep-wake cycle, a recent study provided evidence for a link between WM microstructure and circadian regulation. Here, Rosenberg et al. reported that individuals with an early chronotype, i.e., subjects which tend to wake up early in the morning and prefer to go to bed early in the evening, had higher FA and lower MD than subjects with a late chronotype, mainly in left frontal lobe WM [51]. ...
Sleep is an evolutionarily conserved process required for human health and functioning. Insufficient sleep causes impairments across cognitive domains, and sleep deprivation can have rapid antidepressive effects in mood disorders. However, the neurobiological effects of waking and sleep are not well understood. Recently, animal studies indicated that waking and sleep are associated with substantial cortical structural plasticity. Here, we hypothesized that structural plasticity can be observed after a day of waking and sleep deprivation in the human cerebral cortex. To test this hypothesis, 61 healthy adult males underwent structural magnetic resonance imaging (MRI) at three time points: in the morning after a regular night's sleep, the evening of the same day, and the next morning, either after total sleep deprivation (N=41) or a night of sleep (N=20). We found significantly increased right prefrontal cortical thickness from morning to evening across all participants. In addition, pairwise comparisons in the deprived group between the two morning scans showed significant thinning of mainly bilateral medial parietal cortices after 23hours of sleep deprivation, including the precuneus and posterior cingulate cortex. However, there were no significant group (sleep vs. sleep deprived group) by time interactions and we can therefore not rule out that other mechanisms than sleep deprivation per se underlie the bilateral medial parietal cortical thinning observed in the deprived group. Nonetheless, these cortices are thought to subserve wakefulness, are among the brain regions with highest metabolic rate during wake, and are considered some of the most sensitive cortical regions to a variety of insults. Furthermore, greater thinning within the left medial parietal cluster was associated with increased sleepiness after sleep deprivation. Together, these findings add to a growing body of data showing rapid structural plasticity within the human cerebral cortex detectable with MRI. Further studies are needed to clarify whether cortical thinning is one neural substrate of sleepiness after sleep deprivation.
... • Genome-wide association studies (GWAS) may reveal predictors of tolerability to shift-work. Are some individuals genetically better suited to frequent time-shifts (Rosenberg et al., 2014)? ...
This chapter reviews how circadian rhythms in the gastrointestinal (GI) tract are established and contribute to homeostasis. Circadian rhythms in the digestive system are shaped by a combination of endogenous rhythms and our activity/rest schedules. Most rhythms have obvious rationales, for instance, the temporal partitioning of opposing cellular functions including absorption vs. proliferation and glucose disposal vs. glucose production. Circadian clocks in peripheral tissues are cell-autonomous molecular mechanisms that maintain 24-h periodicity and drive cyclic expression of many rhythmic functions or clock outputs. In general, GI clocks coordinate the induction of physiological processes to match temporal needs. The feeding rhythm is a potent entrainment signal, presumed to operate by shifting the phases of GI clocks and, consequently, clock outputs. Disturbance of clock operation by mutation or detrimental environmental stimuli can disrupt proper functioning of the digestive system and could lead to adverse metabolic changes, obesity, and diabetes. A more thorough understanding of intestinal clocks and their role in nutrition and homeostasis should enhance our ability to address health issues of modern life.
... Emerging adults also tend to stay up late. Evidence shows that individuals who go to bed after 11:00 pm and sleep less than 6 hours/ night are more likely to engage in unhealthy behaviors (e.g., late night snacking, physical inactivity, smoking, alcohol consumption; (Bayon, Leger, Gomez-Merino, Vecchierini, & Chennaoui, 2014;Rosenberg, Maximov, Reske, Grinberg, & Shah, 2014;Schoenborn & Adams, 2008). These unhealthy behaviors have been linked to increased risk of imbalanced glucose metabolism leading to prediabetes or diabetes (MacLeod, Terada, Chahal, & Boule, 2013;Morselli, Leproult, Balbo, & Spiegel, 2010). ...
Design and methods:
A cross-sectional design was used in the parent study involving overweight and obese emerging adults, ages 18-29 years. The goal of the parent study was to screen participants' diabetes risk and identify characteristics of emerging adults with prediabetes (N=107). A sub-sample of respondents (n=34) from the parent study were invited to participate in focus group interviews depending on whether they had prediabetes (three groups) or they did not have prediabetes (four groups). Each focus group interview lasted 90-120 minutes following a semi-structured interview guide. Conventional content analysis was used in the data analysis. Because of the similarities between participants with and without prediabetes, the findings were synthesized and reported in the aggregate. Moreover, during the analysis, the authors decided that rational choice theory provided a useful organizing structure for presenting the data.
Results:
Emerging adults' behavioral decisions were rational reactions to their personal competence, perception of health, environment, and availability of resources to handle problems. Calculation of trade-offs and estimations of resource availability were often used when making decisions.
Conclusions:
Emerging adults choose unhealthy behaviors due to inaccurate information and insufficient competence to practice healthy lifestyles rather than because of laziness or being irrational.
Practice implications:
Behavioral interventions for emerging adults need to help them develop skills to enhance health literacy and problem solving, thereby enhancing their awareness of available resources and decreasing the perceived cost of making healthy choices.
... Sleep deprivation also leads to cognitive impairments (McEwen, 2006). Sleep deprivation has also been associated with increases in fighting behavior (de Paula and Hoshino, 2002), impaired physical, psychological, and emotional health, stress, increased cortisol levels, temporal lobe atrophy (Cho, 2001), chronic disease, elevated mortality risk (Carroll et al., 2016), senescence, accelerated aging (Carroll et al., 2016), structural changes to the brain, and cognitive impairment (Rosenberg et al., 2014). ...
We live in a surprisingly violent world. We experience physical assault, emotional and psychological attack, and even the intellectual violence of manipulation and indoctrination. Psychology is becoming increasingly aware not only of the prevalent violence, but also of the profoundly deleterious impact of said violence on the human mind and body; however, sociology lags behind. Socialization, or our experiences at the hands of agents of socialization, is a key concept in sociology. Every introductory sociology text that is printed devotes and entire chapter to a discussion of socialization and related concepts. However rarely, if at all, is there any indication that sociologists are aware of the profoundly deleterious impact of toxicity (violence, neglect, etc.) in the socialization process. This research note seeks to alleviate this lacuna by providing a concept, toxic socialization, by which sociologists and others (e.g., psychologists, parents, teachers, and anybody involved in the socialization of human beings) can more readily discuss the problem of a violence and neglect in our socialization processes.
... The results suggest that ADHD patients might be characterized by a circadian preference toward eveningness (Baird et al., 2012;Rybak et al., 2007). Eveningness has been also associated to subsyndromal psychiatric symptoms in students (Sheaves et al., 2016) and it has been shown that eveningness chronotypes are more vulnerable for a chronic form of jet lag accompanied with sleep disturbances, vulnerability to depression and higher consumption of nicotine and alcohol (Rosenberg et al., 2014). Further, studies showed significant interactions between the chronotype and sleep efficiency (quality and quantity), which was poorer in evening types (Lehnkering and Siegmund, 2007;Vitale et al., 2015). ...
The pineal gland, as part of the human epithalamus, is the main production site of peripheral melatonin, which promotes the modulation of sleep patterns, circadian rhythms and circadian preferences (morningness vs. eveningness). The present study analyses the pineal gland volume (PGV) and its association with circadian preferences and symptom severity in adult ADHD patients compared to healthy controls. PGV was determined manually using high-resolution 3T MRI (T1-magnetization prepared rapid gradient echo) in medication free adult ADHD patients (N=74) compared to healthy controls (N=86). Moreover, the Morningness-Eveningness Questionnaire (MEQ), the ADHD Diagnostic Checklist and the Wender-Utah Rating Scale were conducted. PGV differed between both groups (patients: 59.9±33.8mm3; healthy controls: 71.4±27.2mm3, P=0.04). In ADHD patients, more eveningness types were revealed (patients: 29%; healthy controls: 17%; P=0.05) and sum scores of the MEQ were lower (patients: 45.8±11.5; healthy controls 67.2±10.1; P<0.001). Multiple regression analyses indicated a positive correlation of PGV and MEQ scores in ADHD (β=0.856, P=0.003) but not in healthy controls (β=0.054, P=0.688). Patients' MEQ scores (β=-0.473, P=0.003) were negatively correlated to ADHD symptoms. The present results suggest a linkage between the PGV and circadian preference in adults with ADHD and an association of the circadian preference to symptom severity. This may facilitate the development of new chronobiological treatment approaches for the add-on treatment in ADHD.
... The lack of association with changes in negative affect is consistent with previous data and hypotheses that morningness-eveningness's relationship to depression is via appetitive motivation and reward pathways rather than the neural pathways associated with negative affect and behavioral inhibition (Hasler, et al., 2010;Hasler, et al., 2012). Recent neuroimaging findings support altered function in the reward circuit of evening-types ( (Hasler, Sitnick, Shaw, & Forbes, 2013), including evening-types diagnosed with insomnia ( (Hasler, et al., 2012), although these neural differences may extend beyond the reward circuit to other regions relevant to sleep, arousal, and affect regulation (Hasler, Insana, James, & Germain, 2013;Rosenberg, Maximov, Reske, Grinberg, & Shah, 2014) An alternate interpretation of our findings is that the observed shifts towards morningness simply reflect participants feeling better in the morning as a result of treatment. Indeed, some CSM items emphasize functioning in the morning without explicit reference to timing, and several published factor analyses of the CSM and its variants have identified a "morning affect" factor in addition to factors more clearly linked to the timing of sleep and activity (Brown, 1993;Caci et al., 2005). ...
Morningness-eveningness (M-E) is typically considered to be a trait-like construct. However, M-E could plausibly shift in concert with changes in circadian or homeostatic processes. We examined M-E changes across three studies employing behavioral or pharmacological sleep treatments. Baseline and posttreatment M-E scores were strongly correlated across all three samples. M-E showed small but systematic changes toward morningness in sleep-disturbed military veterans receiving behavioral interventions. No systematic M-E changes were observed in the two pharmacological studies (sleep-disturbed military veterans and adults with primary insomnia, respectively). In the behavioral study, M-E changes correlated with changes in depression, positive affect, and sleep quality. M-E changes also correlated with changes in positive affect in the adult insomnia group. M-E appears to exhibit state-like aspects in addition to trait-like aspects.
... This is in line with the literature suggesting that evening subjects are more prone to circadian misalignment, social jet-lag, and sleep deprivation (Kanterman et al., 2007;Kim et al., 2013). In turn, these have been associated with cardiovascular disease (Cappuccio et al., 2011;Janszky & Ljung, 2008), obesity (Roenneberg et al., 2012), and even structural cerebral changes (Rosenberg et al., 2014), suggesting that a simple and synthetic tool such as the Self-ME may be relevant to the general population prevention setting (Roenneberg, 2013), as well as the clinical setting itself. Clearly, validation of the Self-ME as a stand-alone question, in different age groups and in diseased populations, is necessary, also in association with actigraphy. ...
The assessment of diurnal preference, or the preferred timing of sleep and activity, is generally based on comprehensive questionnaires such as the Horne-Östberg (HÖ). The aim of the present study was to assess the reliability of a subject's self-classification as extremely morning (Self-MM), more morning than evening (Self-M), more evening than morning (Self-E) or extremely evening (Self-EE) type, based on the last question of the HÖ (Self-ME). A convenience sample of 461 subjects [23.8 ± 4.7 years; 322 females] completed a full sleep-wake assessment, including diurnal preference (HÖ), night sleep quality (Pittsburgh Sleep Quality Index, PSQI), daytime sleepiness (Karolinska Sleepiness Scale, KSS), and habitual sleep-wake timing (12 d sleep diaries; n = 296). Significant differences in HÖ total score were observed between Self-ME classes, with each class being significantly different from neighboring classes (p < 0.0001). Significant differences in sleep-wake timing (bed time, try to sleep and sleep onset, wake up, and get up time) were observed between Self-ME classes. Such differences were maintained when sleep-wake habits were analysed separately on work and free days, and also in a smaller group of 67 subjects who completed the Self-ME as a stand-alone rather than as part of the original questionnaire. Significant differences were observed in the time-course of subjective sleepiness by Self-ME class in both the large and the small group, with Self-MM and Self-M subjects being significantly more alert in the morning and sleepier in the evening hours compared with their Self-E and Self-EE counterparts. Finally, significant differences were observed in night sleep quality between Self-ME classes, with Self-EE/Self-E subjects sleeping worse than their Self-MM/Self-M counterparts, and averaging just over the abnormality PSQI threshold of 5. In conclusion, young, healthy adults can define their diurnal preference based on a single question (Self-ME) in a way that reflects their sleep-wake timing, their sleepiness levels over the daytime hours, and their night sleep quality. Validation of the Self-ME across the decades and in diseased populations seems worthy.
Background/Objectives: Chronotypes significantly influence sleep quality, daily performance, and overall activity levels. Although there is growing evidence indicating that individuals with a late chronotype are more likely to experience cognitive decline, the specific neural mechanisms that contribute to this risk remain unclear. This study aims to explore the relationship between morning and evening preferences and the volumes of subcortical structures in a young, healthy population. Methods: A total of 123 participants (80 females), aged between 18 and 35 years, were recruited. They underwent MRI scans and completed several self-reported assessments, including the morningness–eveningness scale of the Chronotype Questionnaire (ChQ-ME), the amplitude scale of the Chronotype Questionnaire (ChQ-AM), the Epworth Sleepiness Scale (ESS), and the Pittsburgh Sleep Quality Index (PSQI). Participants were classified into early chronotype (EC) and late chronotype (LC) groups based on their ChQ-ME scores. High-resolution T1-weighted imaging was utilized to analyze the volumes of subcortical structures and hippocampal subfields. Results: The volumetric analysis indicated that the LC group showed significant reductions in the right Caudate (p = 0.03) and the left SR-SL-SM (p = 0.03) compared to the EC group. Additionally, a notable leftward hemispheric laterality of the Subiculum (p = 0.048) was observed in the EC group relative to the LC group. Furthermore, the ChQ-AM revealed significant positive (r = 0.23) and negative (r = −0.19) correlations with the volumes of the left thalamus and right amygdala, respectively. The PSQI demonstrated a significant negative correlation (r = −0.21) with the right SR-SL-SM, while the ESS indicated a significant positive correlation (r = 0.24) with the left SR-SL-SM. Multiple regression analysis indicated that variations in daytime sleepiness are linked to the change of the left SR-SL-SM volume. Conclusions: Overall, the findings suggest that chronotype preferences are associated with the changes in the volumes of subcortical structures and hippocampal subfields and highlight the role of chronotypes in the neural mechanisms of these brain structures.
Objective
Evaluation of the biomarkers and their relations with sleep in attention deficit hyperactivity disorder (ADHD) is important for understanding the impairments in cognitive functioning. In this study, we aimed to investigate the brain‐derived neurotrophic factor (BDNF) and sialic acid (Sia) levels, and their possible relations with chronotypes in ADHD.
Methods
The study included 100 drug‐naive children with ADHD and 74 healthy children as controls. Conners' Parent Rating Scale‐Revised (CPRS‐R) scores were used for the severity assessment. Morningness Eveningness Questionnaire (MEQ) was used to determine the chronotypes of participants. ELISA kits were used for the assessment of BDNF and Sia plasma levels.
Results
Levels of BDNF and Sia were found to be statistically significantly higher in the ADHD group compared to healthy children ( p < 0.001, p < 0.001, respectively). BDNF and Sia levels were found to be higher in the ADHD group with eveningness chronotype ( p = 0.045, p = 0.038). The binary logistic regression model was statistically significant ( p = 0.033), higher BDNF and Sia levels were assessed as predictive factors for the diagnosis of ADHD. Also, eveningness chronotype was found as a predictive factor of BDNF and Sia levels in ADHD.
Conclusion
The results indicate that BDNF and Sia levels, which are related to cognitive functions and sleep, increase with the age of ADHD. Eveningness chronotype, connected with the severity of ADHD, is related to BDNF and Sia levels. There is a need for further studies to confirm these results.
The rapid shifts of society have brought about changes in human behavioral patterns, with increased evening activities, increased screen time, and postponed sleep schedules. As an explicit manifestation of circadian rhythms, chronotype is closely intertwined with both physical and mental health. Night owls often exhibit more unhealthy lifestyle habits, are more susceptible to mood disorders, and have poorer physical fitness. Although individual differences in chronotype yield varying consequences, their neurobiological underpinnings remain elusive. Here we carry out a pattern-learning analysis, and capitalize on a vast array of ~ 1,000 phenome-wide phenotypes with three brain-imaging modalities (region volume of gray matter, whiter-matter fiber tracts, and functional connectivity) in 27,030 UK Biobank participants. The resulting multi-level depicts of brain images converge on the basal ganglia, limbic system, hippocampus, as well as cerebellum vermis, thus implicating key nodes in habit formation, emotional regulation and reward processing. Complementary by comprehensive investigations of in-deep phenotypic collections, our population study offers evidence of behavioral pattern disparities linked to distinct chronotype-related behavioral tendencies in our societies.
The circadian rhythm is crucial for physiological and behavioral functions. Chronotype, which represents individual preferences for activity and performance, is associated with human health issues, particularly psychiatric disorders. This narrative review, which focuses on the relationship between chronotype and mental disorders, provides an insight into the potential mechanism. Recent evidence indicates that (1) the evening chronotype is a risk factor for depressive disorders and substance use disorders, whereas the morning chronotype is a protective factor. (2) Evening chronotype individuals with bipolar disorder tend to have more severe symptoms and comorbidities. (3) The evening chronotype is only related to anxiety symptoms. (4) The relationship between chronotype and schizophrenia remains unclear, despite increasing evidence on their link. (5) The evening chronotype is significantly associated with eating disorders, with the majority of studies have focused on binge eating disorders. Furthermore, the underlying mechanisms or influence factors are described in detail, including clock genes, brain characteristics, neuroendocrinology, the light/dark cycle, social factors, psychological factors, and sleep disorders. These findings provide the latest evidence on chronotypes and psychiatric disorders and serve as a valuable reference for researchers.
Moral psychology is used to explore the interaction between regulatory mode (locomotion; assessment) and diurnal preference (“early birds”; “night owls”). Moral and immoral behavior was partly explained by an interaction between regulatory mode and the time of day the task took place. In Studies 1a and 1b, we established a relation between self-reported diurnal preference and regulatory mode using both a chronic measure and an induction: stronger locomotion preferring an earlier time of day; stronger assessment preferring a later time of day. In Study 2, we show that those with a locomotion predominance were less likely to invest in a public good later in the day compared to those with an assessment predominance. Lastly, in Study 3, those induced into an assessment mode were more likely to cheat when randomly assigned to complete a task in the morning compared to those induced into a locomotion mode.
Cognitive impairments are well documented in major depressive disorder (MDD), however, they cannot be fully explained by depressive symptom severity. We investigated how diurnal preference and sleep quality affect cognitive function in MDD. In 34 inpatients with current MDD and 29 healthy controls (HC), we obtained diurnal preference (Morningness-Eveningness Questionnaire, MEQ) and subjective sleep quality (Pittsburgh Sleep Quality Index, PSQI). Further, current mood and neuropsychological performance (Trail Making Test, TMT, part A and B) were assessed in the evening and in the following morning. Patients with MDD performed worse than HC on the TMT-B (particularly requiring executive function), but not on the TMT-A (assessing foremost visuomotor processing speed). In general, participants with evening preference (MEQ-score median split) performed poorer on the TMT than participants with morning preference. Subgroup analyses within MDD confirmed the negative effect of evening preference on the TMT. In addition, patients with severely impaired sleep quality (PSQI > 10) performed cognitively worse than patients with normal to moderately impaired sleep quality (PSQI ≤ 10). The results were largely independent of current mood state. Our findings suggest that evening preference and severely impaired sleep quality independently contribute to cognitive impairment in MDD.
Current evidence suggests that acute depression is associated with reduced total hippocampal volume and regional atrophy. Here, using structural magnetic resonance imaging, we assayed linear effects of chronotype on total hippocampal volume and morphology. Later chronotype was associated with localised atrophy in the subiculum region of the right hippocampus in the absence of changes in total volume. The hippocampus forms a key node in a network of brain regions implicated in emotional regulation and alterations in the structure of this region may underpin, in part, the increased vulnerability for depression in late chronotype individuals.
Diffusion MRI is an efficient and widely used technique for the investigation of tissue structure and organisation in vivo. Multiple phenomenological and biophysical diffusion models are intensively exploited for the analysis of the diffusion experiments. However, the verification of the applied diffusion models remains challenging. In order to provide a “gold standard” and to assess the accuracy of the derived parameters and the limitations of the diffusion models, anisotropic diffusion phantoms with well known architecture are demanded. In the present work we built four anisotropic diffusion phantoms consisting of hollow microcapillaries with very small inner diameters of 5, 10 and 20 m and outer diameters of 90 and 150 m. For testing the suitability of these phantoms, we performed diffusion measurements on all of them and evaluated the resulting data with a set of popular diffusion models, such as diffusion tensor and diffusion kurtosis imaging, a two compartment model with intra- and extra-capillary water spaces using bi-exponential fitting, and time-dependent diffusion coefficients in Mitra’s limit. The perspectives and limitations of these diffusion phantoms are presented and discussed.
Visualisation of living tissue structure and function is a challenging problem of modern imaging techniques. Diffusion MRI allows one to probe in vivo structures on a micrometer scale. However, conventional diffusion measurements are time-consuming procedures, because they require several measurements with different gradient directions. Considerable time savings are therefore possible by measurement schemes that generate an isotropic diffusion weighting in a single shot. Multiple approaches for generating isotropic diffusion weighting are known and have become very popular as useful tools in clinical research. Thus, there is a strong need for a comprehensive comparison of different isotropic weighting approaches. In the present work we introduce two new sequences based on simple (co)sine modulations and compare their performance to established q-space magic-angle spinning sequences and conventional DTI, using a diffusion phantom assembled from microcapillaries and in vivo experiments at 7T. The advantages and disadvantages of all compared schemes are demonstrated and discussed.
The stable and persisting preference for activities in the late evening (i.e. eveningness) is associated with a higher risk for depression, suicidality, and non-remission in major depression. The present study investigated symptom patterns in hospitalized patients with depressive syndromes in relation to morningness-eveningness (chronotypes). Depressive symptoms (Beck Depression Inventory [BDI-II]) and chronotype (German version of the Morningness-Eveningness Questionnaire [d-MEQ]) were assessed after admission and before discharge in inpatients with mainly major depression. Group differences of BDI-II single items and three BDI-II factors (cognitive, affective, somatic) between patients divided at the d-MEQ sample median into “morning preference” (MP) and “evening preference” (EP) were calculated. Data from 64 consecutively admitted patients (31MP/33EP) were analyzed. Both groups (MP/EP) were comparable regarding age, sex, diagnosis, length of stay, and subjective sleep quality, BDI-II scores were significantly higher in EP than in MP at admission. At admission and discharge, cognitive symptoms were significantly more pronounced in EP vs. MP; non-significant differences between EP and MP were found for affective and somatic symptoms. The results underline the importance of the trait-like chronotype for severity and symptomatology in patients with depressive disorders. The patients’ chronotype should be taken into account in diagnostics and treatment of depressive disorders.
Animals, human beings among them, can adapt their behavior to (predictable) temporal fluctuations in the environment (such as day and night alternation, food and water availability, or social contact) by learning and memory processes interacting with an endogenous circadian clock. Behavioral, physiological, and biochemical circadian rhythms are crucial for the good mental health of an individual and rely on the integrity and functioning of the circadian system. The master clock in the suprachiasmatic nucleus synchronizes independent circadian peripheral clocks, localized in other brain areas, organs, and tissues to the appropriate phases by neural and humoral signals. Thus, circadian clocks orchestrate interactions between the organism’s internal processes and the environment in healthy, but also in pathological, conditions. This chapter focuses on the main components of the circadian system; the temporal organization of cognitive functions at the molecular, biochemical, and behavioural levels and their clock-mediated regulation; as well as on factors that could disrupt the normal functioning of the circadian system and thus, contribute to the etiology of cognitive disorders.
In human beings, homeostatic and circadian sleep-wake regulatory processes work together for the maintenance of sleep and wakefulness at appropriate times within the 24-hour light-dark cycle. The interaction between these processes also determines time-of-day modulations in sleepiness and alertness levels, and affects performance in a series of cognitive tasks. Recent evidence suggests that similar modulation patterns can also be detected in the cerebral correlates underlying successful cognitive functions.
Background and purpose:
ESRD results in excessive accumulation of urea and toxic metabolites. Hemodialysis is usually performed to maintain health in patients with ESRD; however, it may cause silent white matter alterations in the earlier stages. Hence, this study aimed to perform voxelwise diffusion tensor analysis for global detection of subtle white matter alterations in patients with ESRD.
Materials and methods:
Twenty-eight patients with ESRD and 25 age-matched control subjects were enrolled in this study. Each subject underwent CASI assessment and DTI. After spatial normalization of DTI images, voxelwise statistical analyses were performed to compare DTI parameters between the 2 groups.
Results:
In patients with ESRD, AD, RD, and MD values were significantly increased, whereas the FA value was significantly decreased, mostly in the corpus callosum, bilateral sagittal stratum, and pons. Multiple regression analysis further revealed that both RD and MD were positively correlated with the duration of hemodialysis in the pons; however, no significant correlation was observed with FA. Negative correlations of RD and MD and a positive correlation of FA with the CASI score were observed in the corona radiata.
Conclusions:
We concluded that voxelwise DTI analysis is helpful in the detection of white matter alterations caused by hemodialysis.
Cannabis use typically begins during adolescence and early adulthood, a period when cannabinoid receptors are still abundant in white matter pathways across the brain. However, few studies to date have explored the impact of regular cannabis use on white matter structure, with no previous studies examining its impact on axonal connectivity. The aim of this study was to examine axonal fibre pathways across the brain for evidence of microstructural alterations associated with long-term cannabis use and to test whether age of regular cannabis use is associated with severity of any microstructural change. To this end, diffusion-weighted magnetic resonance imaging and brain connectivity mapping techniques were performed in 59 cannabis users with longstanding histories of heavy use and 33 matched controls. Axonal connectivity was found to be impaired in the right fimbria of the hippocampus (fornix), splenium of the corpus callosum and commissural fibres. Radial and axial diffusivity in these pathways were associated with the age at which regular cannabis use commenced. Our findings indicate long-term cannabis use is hazardous to the white matter of the developing brain. Delaying the age at which regular use begins may minimize the severity of microstructural impairment.
Sleep has strong links to the symptomology of fibromyalgia syndrome (FMS), a diffuse musculoskeletal pain disorder. Information about the involvement of the circadian clock is, however, sparse. In this study, 1548 individuals with FMS completed an online survey containing questions on demographics, stimulant consumption, sleep quality, well-being and subjective pain, chronotype (assessed by the Munich ChronoType Questionnaire, MCTQ), and FMS impact. Chronotype (expressed as the mid-sleep-point on free days, corrected for sleep deficit on workdays, MSFsc) significantly correlated with stress-ratings, so-called “memory failures in everyday life,” fatigue, FMS impact, and depression but not with anxiety. When chronotypes were categorized into 3 groups (early, intermediate, late), significant group differences were found for sum scores of perceived stress, memory failures in everyday life, fatigue, FMS impact, and depression but not anxiety, with late chronotypes being more affected than early chronotypes. Sleepiness ratings were highest in early chronotypes. Challenges of sleep quality and subjective pain were significantly increased in both early and late chronotypes. The results show that according to their reports, late chronotypes are more affected by fibromyalgia.
Individual differences in sleep and diurnal preference associate with physical and mental health characteristics, but few genetic determinants of these differences have been identified. A variable number tandem repeat (VNTR) polymorphism in the PERIOD3 (PER3) gene (rs57875989) has been reported to associate with diurnal preference, i.e., preferred timing of waking and sleep. Here, the authors investigate in a prospective single-candidate genetic variant study whether allelic variation for this polymorphism associates also with reported actual sleep timing and sleep duration, as well as psychological and health measures. Six hundred and seventy-five subjects, aged 20 to 35 yrs, completed questionnaires to assess sleep and psychological and health characteristics and were genotyped for the PER3 VNTR. Homozygosity for the longer allele (PER3(5/5)) of the VNTR was associated with increased morning preference, earlier wake time and bedtime, and reduced daytime sleepiness. Separate analyses of work and rest days demonstrated that the increase in time in bed during rest days was greatest in PER3(5/5) homozygotes. PER3 genotype modified the effects of sleep timing and duration on fluid intelligence and body mass index. Genotype was not associated with physical or psychological characteristics as assessed by the SF-36 Health Questionnaire, the General Health Questionnaire, the Big Five Inventory, the Behavioral Inhibition System-Behavioral Activation System scales, and the Positive and Negative Affect Scale, even though these measures varied significantly with diurnal preference as assessed by the Morningness-Eveningness Questionnaire. Whereas diurnal preference also predicts mental health and psychological characteristics, as well as sleep timing, the PER3 VNTR specifically affects measures of sleep timing and may also modify the effects of sleep on health outcome measures.
In public health, mood disorders are among the most important mental impairments. Patients with depressive episodes exhibit daily mood variations, abnormal patterns in sleep-wake behavior, and in the daily rhythms of several endocrine-metabolic parameters. Although the relationship between the sleep/circadian processes and mood disorders is poorly understood, clock-related therapies, such as light therapy, sleep deprivation, and rigid sleep schedules, have been shown to be effective treatments. Several studies investigated the relationship between circadian phenotype (chronotype) and depression. These focused mainly on urban populations and assessed diurnal preferences (Morningness-Eveningness score) rather than the actual timing of sleep and activity. Here, we used the Beck Depression Inventory (BDI) in an essentially rural population (N?=?4051), and investigated its relation to circadian phenotype (chronotype and social jetlag), assessed with the Munich Chronotype Questionnaire (MCTQ). In our study design, we (i) normalized both chronotype and BDI scores for age and sex (MSF(sas) and BDI(as), respectively); (ii) calculated individual social jetlag (misalignment of the biological and social time); and (iii) investigated the relationship between circadian phenotypes and BDI scores in a population homogeneous in respect to culture, socioeconomic factors, and daily light exposure. A 15.65% (N?=?634) of the participants showed mild to severe depressive BDI scores. Late chronotypes had a higher BDI(as) than intermediate and early types, which was independent of whether or not the participants were smokers. Both chronotype and BDI(as) correlated positively with social jetlag. BDI(as) was significantly higher in subjects with >2?h of social jetlag than in the rest of the population?again independent of smoking status. We also compared chronotype and social jetlag distributions between BDI categories (no symptoms, minimal symptoms, and mild to severe symptoms of depression) separately for men and women and for four age groups; specifically in the age group 31?40 yrs, subjects with mild to severe BDI scores were significantly later chronotypes and suffered from higher social jetlag. Our results indicate that misalignment of circadian and social time may be a risk factor for developing depression, especially in 31- to 40-yr-olds. These relationships should be further investigated in longitudinal studies to reveal if reduction of social jetlag should be part of prevention strategies. (Author correspondence: karla.allebrandt@med.uni-muenchen.de ).
Compared to the substantial volume of research on the general health consequences associated with chronic smoking, little research has been specifically devoted to the investigation of its effects on human neurobiology and neurocognition. This review summarizes the peer-reviewed literature on the neurocognitive and neurobiological implications of chronic cigarette smoking in cohorts that were not seeking treatment for substance use or psychiatric disorders. Studies that specifically assessed the neurocognitive or neurobiological (with emphasis on computed tomography and magnetic resonance-based neuroimaging studies) consequences of chronic smoking are highlighted. Chronic cigarette smoking appears to be associated with deficiencies in executive functions, cognitive flexibility, general intellectual abilities, learning and/or memory processing speed, and working memory. Chronic smoking is related to global brain atrophy and to structural and biochemical abnormalities in anterior frontal regions, subcortical nuclei and commissural white matter. Chronic smoking may also be associated with an increased risk for various forms of neurodegenerative diseases. The existing literature is limited by inconsistent accounting for potentially confounding biomedical and psychiatric conditions, focus on cross-sectional studies with middle aged and older adults and the absence of studies concurrently assessing neurocognitive, neurobiological and genetic factors in the same cohort. Consequently, the mechanisms promoting the neurocognitive and neurobiological abnormalities reported in chronic smokers are unclear. Longitudinal studies are needed to determine if the smoking-related neurobiological and neurocognitive abnormalities increase over time and/or show recovery with sustained smoking cessation.
In other disciplines, white matter (WM) differences have been linked to cognitive impairments. This study sets out to clarify whether similar microstructural differences in WM tracts predict a person's cognitive vulnerability to the effects of total sleep deprivation (TSD).
Participants completed a simple visual-motor task both before and after 24 h of TSD. Using a median split on the percent change in accuracy from pre-TSD to post-TSD, participants were separated into susceptibility groups. A diffusion tensor MR imaging (DTI) scan was acquired from each participant, and fractional anisotropy (FA) was calculated, examined across the brain, and compared between susceptibility groups.
University of Texas at Austin.
Thirty-two West Point cadets (9 females, 23 males) between 19 and 25 years of age.
Participant susceptibility to TSD was correlated with lower FA values in multiple regions of white matter, including the genu of corpus callosum and ascending and longitudinal white matter pathways. Significantly higher FA values in those less vulnerable to TSD, indicating increased neural connectivity and WM organization, may moderate the cognitive effects of sleep deprivation.
Differences in distributed WM pathways reflect, and may contribute to, a person's ability to function effectively when sleep deprived. The widespread nature of this effect supports previous views that TSD has a global effect on brain functioning.
Gilles de la Tourette syndrome (GTS) is a neuropsychiatric disorder characterized by multiple motor and vocal tics. Previous structural MRI studies have identified regional abnormalities in grey matter, especially in the basal ganglia. These findings are consistent with the assumption of alterations in cortico-striato-thalamo-cortical circuits and dopaminergic neurotransmission playing a major role in the pathophysiology of GTS. Additionally, recent imaging studies suggested an involvement of sensory-motor cortices in the pathophysiology of GTS. However, little is known about the role of white matter changes in GTS. In this study, we aimed to examine whether GTS is associated with abnormalities in white matter microstructure and whether these changes are correlated with tic severity. In a morphometric study based on diffusion tensor MRI of the whole brain, we compared brain tissue diffusion characteristics between 15 unmedicated adults with GTS without psychiatric co-morbidity and 15 healthy age- and sex-matched controls. We performed voxel-based morphometry (VBM) of regional fractional anisotropy (FA) values to identify regional differences in white matter microstructure between the groups. We also tested for a linear relationship between regional FA values and clinical scores of tic severity. Probabilistic fibre tracking was applied to characterize anatomical connectivity of those areas showing differences in regional FA. Compared with healthy controls, GTS patients showed bilateral FA increases in white matter underlying the post- and precentral gyrus, below the left supplementary motor area, and in the right ventro-postero-lateral part of the thalamus. The peak increase in FA was located below the left postcentral gyrus. Probabilistic tractography identified transcallosal and ipsilateral cerebello-thalamo-cortical pathways of the somatosensory system passing through this subcortical region. In patients, regional FA in this region showed an inverse linear relationship with tic severity. These findings demonstrate, for the first time, structural alterations in somatosensory pathways in GTS. Changes of water diffusion characteristics point towards reduced branching in somatosensory pathways in GTS patients. The negative correlation between higher regional FA values and fewer tics suggests that these alterations of white matter microstructure represent adaptive reorganization of somatosensory processing in GTS.
Neuronal degeneration in the precentral gyrus alone cannot account for the occurrence of spastic paresis in motor neuron diseases. To look for more extensive cortical atrophy we measured MRIs of the upper parts of the frontal and parietal lobes in 11 sporadic cases of classical amyotrophic lateral sclerosis (ALS), eight patients with primary lateral sclerosis (PLS) and an age- and sex-matched group of 49 neurologically normal people. None of the patients had overt dementia or other mental diseases. In PLS there is progressive spastic paresis but in contrast to ALS there is no lower motor neuron degeneration. The surface area of the precentral gyri and the amount of underlying white matter in PLS were consistently approximately 75% of the normal size. By contrast, there was some shrinkage of the precentral gyri in some of the ALS patients but the mean measurements for the group did not differ significantly from the controls. Anterior to the precentral sulci, the cortical surface area in PLS was approximately 85% of that of the controls, with correspondingly reduced white matter. In ALS the cortical surface areas of the anterior frontal lobes did not differ from those of the controls, but the amount of underlying white matter was reduced almost as much in ALS as it was in PLS. The measured changes in the frontal lobes suggest that in PLS there is simultaneous atrophy of the primary, premotor and supplementary motor areas of the cortex, with consequent degeneration of corticospinal and corticoreticular axons descending through the underlying white matter. These changes could account for the progressive upper motor neuron syndrome. In ALS, with no significant frontal cortical atrophy, the shrinkage of the white matter may be due to degeneration of axons projecting to the frontal cortex from elsewhere. Deprivation of afferents could explain the diminution of motor functions of the frontal lobes in ALS and also the changes in word fluency, judgement and attention that can be detected by appropriate testing in some patients with the disease. Incidental observations include slightly larger parietal lobes but no difference in the frontal lobes in men as compared with women. There was also a small but significant decrease in size of the normal frontal lobes with age. The latter change was much smaller than the atrophy seen in patients with ALS and PLS.
Motor development and cognitive development may be fundamentally interrelated. Contrary to popular notions that motor development begins and ends early, whereas cognitive development begins and ends later, both motor and cognitive development display equally protracted developmental timetables. When cognitive development is perturbed, as in a neurodevelopmental disorder, motor development is often adversely affected. While it has long been known that the striatum functions as part of a circuit with dorsolateral prefrontal cortex, it is suggested here that the same is true for the cerebellum and that the cerebellum may be important for cognitive as well as motor functions. Like prefrontal cortex, the cerebellum reaches maturity late. Many cognitive tasks that require prefrontal cortex also require the cerebellum. To make these points, evidence is summarized of the close co-activation of the neocerebellum and dorsolateral prefrontal cortex in functional neuroimaging, of similarities in the cognitive sequelae of damage to dorsolateral prefrontal cortex and the neocerebellum, of motor deficits in "cognitive" developmental disorders, and of abnormalities in the cerebellum and in prefrontal cortex in the same developmental disorders.
We studied the influence of genetic factors on individual differences in morningness-eveningness in a sample of Dutch twin families. Data were collected from adolescent twins (mean age 17.8 yr) and their parents (mean age of fathers 48.0 yr and of mothers 46.0 yr) and a sample of older twins (mean age 46.5 yr). Scores on morningness-eveningness were rated on a 5-point scale. Parents were more morning oriented than their children, and women were more morning oriented than men. With a twin-family study, separation of genetic and environmental influences on variation in morningness-eveningness is possible. Including parents and older twins in the study makes it possible to explore generation differences in these effects. The correlation between monozygotic twins was more than twice the correlation between dizygotic twins. This indicates that genetic effects may not operate in an additive manner. Therefore, a model that included genetic dominance was explored. Biometrical model fitting showed no sex differences for the magnitude of genetic and environmental factors. The total heritability--the sum of additive and nonadditive genetic influences--for morningness-eveningness was 44% for the younger generation and 47% for the older generation. However, the genetic correlation between the generations turned out to be lower than 0.5, suggesting that different genes for morningness-eveningness are expressed in both generations.
Human behavior shows large interindividual variation in temporal organization. Extreme "larks" wake up when extreme "owls" fall asleep. These chronotypes are attributed to differences in the circadian clock, and in animals, the genetic basis of similar phenotypic differences is well established. To better understand the genetic basis of temporal organization in humans, the authors developed a questionnaire to document individual sleep times, self-reported light exposure, and self-assessed chronotype, considering work and free days separately. This report summarizes the results of 500 questionnaires completed in a pilot study individual sleep times show large differences between work and free days, except for extreme early types. During the workweek, late chronotypes accumulate considerable sleep debt, for which they compensate on free days by lengthening their sleep by several hours. For all chronotypes, the amount of time spent outdoors in broad daylight significantly affects the timing of sleep: Increased self-reported light exposure advances sleep. The timing of self-selected sleep is multifactorial, including genetic disposition, sleep debt accumulated on workdays, and light exposure. Thus, accurate assessment of genetic chronotypes has to incorporate all of these parameters. The dependence of human chronotype on light, that is, on the amplitude of the light:dark signal, follows the known characteristics of circadian systems in all other experimental organisms. Our results predict that the timing of sleep has changed during industrialization and that a majority of humans are sleep deprived during the workweek. The implications are far ranging concerning learning, memory, vigilance, performance, and quality of life.
The purpose of this study was to evaluate homeostatic and circadian sleep process in 'larks' and 'owls' under daily life conditions. Core body temperature, subjective sleepiness and waking electroencephalogram (EEG) theta-alpha activity (6.25-9 Hz) were assessed in 18 healthy men (nine morning and nine evening chronotypes, 21.4 +/- 1.9 years) during a 36-h constant routine that followed a week of a normal 'working' sleep-wake schedule (bedtime: 23.30 h, wake time: 07.30 h). The phase of the circadian rhythm of temperature and sleepiness occurred respectively, 1.5 h (P = 0.01) and 2 h (P = 0.009) later in evening- than in morning-type subjects. Only morning-type subjects showed a bimodal rhythm of sleep-wake propensity. The buildup of subjective sleepiness, as quantified by linear regression, was slower in evening than in morning types (P = 0.04). The time course of EEG theta-alpha activity of both chronotypes could be closely fitted by an exponential curve. The time constant of evening types was longer than that of morning types (P = 0.03), indicating a slower increase in sleep pressure during extended wakefulness. These results suggest that both the circadian signal and the kinetics of sleep pressure buildup differ between the two chronotypes even under prior naturalistic conditions mimicking the usual working day.
To examine structural abnormalities in subregions of the prefrontal cortex in elderly patients with depression, the authors explored differences in gray matter, white matter, and CSF volumes by applying a parcellation method based on magnetic resonance imaging (MRI).
Twenty-four elderly patients with major depression and 19 group-matched comparison subjects were studied with high-resolution MRI. Cortical surface extraction, tissue segmentation, and cortical parcellation methods were applied to obtain volume measures of gray matter, white matter, and CSF in seven prefrontal subregions: the anterior cingulate, gyrus rectus, orbitofrontal cortex, precentral gyrus, superior frontal cortex, middle frontal cortex, and inferior frontal cortex.
Highly significant bilateral volume reductions in gray matter were observed in the anterior cingulate, the gyrus rectus, and the orbitofrontal cortex. Depressed patients also exhibited significant bilateral white matter volume reductions and significant CSF volume increases in the anterior cingulate and the gyrus rectus. Finally, the depressed group showed significant CSF volume reductions in the orbitofrontal cortex relative to the comparison subjects. None of the other regions examined revealed significant structural abnormalities.
The prominent bilateral gray matter deficits in the anterior cingulate and the gyrus rectus as well as the orbitofrontal cortex may reflect disease-specific modifications of elderly depression. The differential pattern of abnormalities detected in the white matter and CSF compartments imply that distinct etiopathological mechanisms might underlie the structural cortical changes in these regions.
This paper analyses the influence of and possible interaction between chronotype (Morning-types, Neither-types and Evening-types} and personality dimensions (neuroticism, extroversion and psychoticism) in the daily consumption of alcohol and psychostimulants (nicotine and caffeine). In a sample of 537 subjects (257 men and 280 women), who were students and professionals with different but fixed work schedules, there were significant differences among the chronotypes regarding the consumption of all the above. Evening-types consumed more alcohol, nicotine and caffeine (coffee and cola), while Morning-types consumed more caffeine from tea. Personality was only related to the consumption of cola: the greater the neuroticism the higher the consumption of this beverage. Stimulant drinks showed various types of interaction with personality types, which revealed a complex pattern of group action. The results stress the need to consider chronotype as a contributory psychological factor in a multi-causal model of consumption of psychoactive substances.
Thisarticle has been written in response to Dr. Fred L. Bookstein's article entitled ‘“Voxel-Based Morphometry” Should Not Be Used with Imperfectly Registered Images’ in this issue of NeuroImage. We will address three main issues: (i) Dr. Bookstein appears to have misunderstood the objective of voxel-based morphometry (VBM) and the nature of the continuum we referred to. (ii) We agree with him when he states that findings from VBM can pertain to systematic registration errors during spatial normalization. (iii) His argument about voxelwise tests on smooth data holds in the absence of error variance, but is of no consequence when using actual data. We first review the tenets of VBM, paying particular attention to the relationship between VBM and tensor-based morphometry. The last two sections of this response deal with the specific concerns raised by Dr. Bookstein.
A group of 232 adult subjects was administered the Morningness-Eveningness Questionnaire to assess their individual circadian typology and a battery of questionnaires of personality and psychological and psychosomatic disorders (Beck Depression Inventory; Bortner Type A Scale; Eysenck Personality Questionnaire; Jenkins Activity Survey; Middlesex Hospital Questionnaire; Strelau Temperament Inventory). Significant correlations between circadian typology scores and data relative to personality, psychosomatic disorders, and stress-prone behaviour were found. Evening types reported psychological and psychosomatic disturbances more frequently and intensively than morning types, and showed more problems in coping with environmental and social demands. The relevance of the morningness-eveningness dimension for research on stress and cardiovascular diseases is discussed.
Sex hormones, including testosterone, are hypothesized to have an influence on the human circadian system. We sampled male students in the period after adolescence. We used the Composite Scale of Morningness (CSM) to assess chronotype and saliva testosterone sampling in 106 University students (23.87±3.56 years; range 19-37) between 26.4.2011 and 6.5.2011, always between 0800h and 0900h. There was a significant negative relationship between CSM scores and saliva testosterone (r(s)=-0.220, p=0.023, two-tailed test) but not between testosterone and average sleep length. Age and testosterone did not correlate with each other nor did age and CSM scores. Our data suggest that chronotype in men might be influenced by testosterone and that high testosterone levels lead to a stronger evening-orientation. Sleep duration was uncorrelated with testosterone, suggesting that timing of sleep - rather than sleep length itself - is influenced by testosterone.
Magnetic resonance images tend to be influenced by various random factors usually referred to as "noise". The principal sources of noise and related artefacts can be divided into two types: arising from hardware (acquisition coil arrays, gradient coils, field inhomogeneity); and arising from the subject (physiological noise including body motion, cardiac pulsation or respiratory motion). These factors negatively affect the resolution and reproducibility of the images. Therefore, a proper noise treatment is important for improving the performance of clinical and research investigations. Noise reduction becomes especially critical for the images with a low signal-to-noise ratio, such as those typically acquired in diffusion tensor imaging at high diffusion weightings. The standard methods of signal correction usually assume a uniform distribution of the standard deviation of the noise across the image and evaluate a single correction parameter for the whole image. We pursue a more advanced approach based on the assumption of an inhomogeneous distribution of noise in space and evaluate correction factors for each voxel individually. The Rician nature of the underlying noise is considered for low and high signal-to-noise ratios. The approach developed here has been examined using numerical simulations and in vivo brain diffusion tensor imaging experiments. The efficacy and usefulness of this approach is demonstrated here and the resultant effective tool is described.
During puberty, human adolescents develop a later chronotype, exhibiting a delay in the timing of rest and activity as well as other daily physiological rhythms. The purpose of this study was to determine whether similar changes in chronotype occur during puberty in a laboratory rodent species, and, if so, to determine whether they are due to pubertal hormones acting on the circadian timekeeping system. To test this hypothesis, we carefully tracked daily activity rhythms across puberty in the slow-developing rodent Octodon degus. We confirmed that male degus showed a large reorganization of activity rhythms that correlated with secondary sex development during puberty, including a loss of bimodality and a 3-5 h phase-advance. Similar to humans, this circadian reorganization showed distinct sex differences, with females showing little change during puberty in two separate experiments. Prepubertal gonadectomy (GDX) eliminated the changes, whereas SHAM gonadectomy had little impact. Therefore, gonadal hormones are likely to play a role in pubertal changes in chronotype in this rodent species. Using evidence from a variety of species, including our recent studies in the rat, we conclude that chronotype changes during puberty are a well-demonstrated phenomenon in mammals.
The aim of the present study was to analyze the circadian rhythmicity in handwriting kinematics and legibility and to compare the performance between Dutch and German writers. Two subject groups underwent a 40 h sleep deprivation protocol under Constant Routine conditions either in Groningen (10 Dutch subjects) or in Berlin (9 German subjects). Both groups wrote every 3h a test sentence of similar structure in their native language. Kinematic handwriting performance was assessed with a digitizing tablet and evaluated by writing speed, writing fluency, and script size. Writing speed (frequency of strokes and average velocity) revealed a clear circadian rhythm, with a parallel decline during night and a minimum around 3:00 h in the morning for both groups. Script size and movement fluency did not vary with time of day in neither group. Legibility of handwriting was evaluated by intra-individually ranking handwriting specimens of the 13 sessions by 10 German and 10 Dutch raters. Whereas legibility ratings of the German handwriting specimens deteriorated during night in parallel with slower writing speed, legibility of the Dutch handwriting deteriorated not until the next morning. In conclusion, the circadian rhythm of handwriting kinematics seems to be independent of script language at least among the two tested western countries. Moreover, handwriting legibility is also subject to a circadian rhythm which, however, seems to be influenced by variations in the assessment protocol.
Previous volumetric developmental MRI studies of the brain have shown white matter development continuing through adolescence and into adulthood. This review presents current findings regarding white matter development and organization from diffusion MRI studies. The general trend during adolescence (age 12-18 years) is towards increasing fractional anisotropy (FA) with age and decreasing mean diffusivity (MD) with age, findings primarily due to decreasing radial diffusivity with age. However, results of studies vary as to the regional specificity of such age-related changes, likely due in part to methodological issues. Another general trend is for FA to positively correlate and MD to negatively correlate with cognitive function. This trend is however region-specific, task-specific, and population-specific; some studies have in fact found negative correlations of FA and positive correlations of MD in specific regions with specific measures of cognitive performance. There are also published reports of sexual dimorphism in white matter development, indicating differing developmental trajectories between males and females as well as differing relationships developmentally between white matter architecture and cognitive function. There is a need for more research to further elucidate the development of white matter and its relation to cognitive function during this critical developmental period.
Bipolar disorder (BD) is a common and debilitating condition, often beginning in adolescence. Converging evidence from genetic and neuroimaging studies indicates that white matter abnormalities may be involved in BD. In this study, we investigated white matter structure in adolescents with familial bipolar disorder using diffusion tensor imaging (DTI) and a whole brain analysis.
We analyzed DTI images using tract-based spatial statistics (TBSS), a whole-brain voxel-by-voxel analysis, to investigate white matter structure in 21 adolescents with BD, who also were offspring of at least one parent with BD, and 18 age- and IQ-matched control subjects. Fractional anisotropy (FA; a measure of diffusion anisotropy), trace values (average diffusivity), and apparent diffusion coefficient (ADC; a measure of overall diffusivity) were used as variables in this analysis. In a post hoc analysis, we correlated between FA values, behavioral measures, and medication exposure.
Adolescents with BD had lower FA values than control subjects in the fornix, the left mid-posterior cingulate gyrus, throughout the corpus callosum, in fibers extending from the fornix to the thalamus, and in parietal and occipital corona radiata bilaterally. There were no significant between-group differences in trace or ADC values and no significant correlation between behavioral measures, medication exposure, and FA values.
Significant white matter tract alterations in adolescents with BD were observed in regions involved in emotional, behavioral, and cognitive regulation. These results suggest that alterations in white matter are present early in the course of disease in familial BD.
Morningness/eveningness (M/E) is a stable, quantifiable measure reflecting preferred circadian phase. Two prior studies suggest that bipolar I disorder (BP1) cases are more likely to have lower M/E scores, i.e., be evening types compared with control groups. These studies did not recruit controls systematically and did not evaluate key clinical variables. We sought to replicate the reported associations in a large, well defined sample, while evaluating potential confounding factors. Adults with bipolar disorder (BP) were compared with community controls drawn randomly from the same residential areas (190 cases and 128 controls). M/E was evaluated using the composite scale of morningness (CSM). After accounting for variables correlated with M/E, BP cases had significantly lower CSM scores than controls (i.e., more evening-type or fewer morning-type). There were no significant differences in M/E scores between BP1 or BP2 disorder cases (n=134 and 56, respectively). CSM scores were stable over approximately 2 years in a subgroup of participants (n=52). Individuals prescribed anxiolytic drugs, antidepressants, antipsychotic drugs, mood stabilizers or stimulant drugs had significantly lower age-corrected CSM scores compared with persons not taking these drugs. BP cases are more likely to be evening types, suggesting circadian phase delay in BP cases. Individuals with elevated depressive mood scores are more likely to be evening types. Our results suggest a replicable relationship between circadian phase and morbid mood states.
Astrocytes modulate neuronal activity by releasing chemical transmitters via a process termed gliotransmission. The role of this process in the control of behavior is unknown. Since one outcome of SNARE-dependent gliotransmission is the regulation of extracellular adenosine and because adenosine promotes sleep, we genetically inhibited the release of gliotransmitters and asked if astrocytes play an unsuspected role in sleep regulation. Inhibiting gliotransmission attenuated the accumulation of sleep pressure, assessed by measuring the slow wave activity of the EEG during NREM sleep, and prevented cognitive deficits associated with sleep loss. Since the sleep-suppressing effects of the A1 receptor antagonist CPT were prevented following inhibition of gliotransmission and because intracerebroventricular delivery of CPT to wild-type mice mimicked the transgenic phenotype, we conclude that astrocytes modulate the accumulation of sleep pressure and its cognitive consequences through a pathway involving A1 receptors.
Typically in neuroimaging we are looking to extract some pertinent information from imperfect, noisy images of the brain. This might be the inference of percent changes in blood flow in perfusion FMRI data, segmentation of subcortical structures from structural MRI, or inference of the probability of an anatomical connection between an area of cortex and a subthalamic nucleus using diffusion MRI. In this article we will describe how Bayesian techniques have made a significant impact in tackling problems such as these, particularly in regards to the analysis tools in the FMRIB Software Library (FSL). We shall see how Bayes provides a framework within which we can attempt to infer on models of neuroimaging data, while allowing us to incorporate our prior belief about the brain and the neuroimaging equipment in the form of biophysically informed or regularising priors. It allows us to extract probabilistic information from the data, and to probabilistically combine information from multiple modalities. Bayes can also be used to not only compare and select between models of different complexity, but also to infer on data using committees of models. Finally, we mention some analysis scenarios where Bayesian methods are impractical, and briefly discuss some practical approaches that we have taken in these cases.
Eight subjects were kept awake and active overnight in a sleep lab isolated from environmental time cues. Ambulatory EEG and EOG were continuously recorded and sleepiness ratings carried out every two hours as was a short EEG test session with eyes open for 5 min and closed for 2 min. The EEG was subjected to spectral analysis and the EOG was visually scored for slow rolling eye movements (SEM). Intrusions of SEM and of alpha and theta power density during waking, open-eyed activity strongly differentiated between high and low subjective sleepiness (the differentiation was poorer for closed eyes) and the mean intraindividual correlations between subjective and objective sleepiness were very high. Still, the covariation was curvilinear; physiological indices of sleepiness did not occur reliably until subjective perceptions fell between "sleepy" and "extremely sleepy-fighting sleep"; i.e. physiological changes due to sleepiness are not likely to occur until extreme sleepiness is encountered. The results support the notion that ambulatory EEG/EOG changes may be used to quantify sleepiness.
Despite the prevalence of sleep complaints among psychiatric patients, few questionnaires have been specifically designed to measure sleep quality in clinical populations. The Pittsburgh Sleep Quality Index (PSQI) is a self-rated questionnaire which assesses sleep quality and disturbances over a 1-month time interval. Nineteen individual items generate seven "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The sum of scores for these seven components yields one global score. Clinical and clinimetric properties of the PSQI were assessed over an 18-month period with "good" sleepers (healthy subjects, n = 52) and "poor" sleepers (depressed patients, n = 54; sleep-disorder patients, n = 62). Acceptable measures of internal homogeneity, consistency (test-retest reliability), and validity were obtained. A global PSQI score greater than 5 yielded a diagnostic sensitivity of 89.6% and specificity of 86.5% (kappa = 0.75, p less than 0.001) in distinguishing good and poor sleepers. The clinimetric and clinical properties of the PSQI suggest its utility both in psychiatric clinical practice and research activities.
The need for a simply applied quantitative assessment of handedness is discussed and some previous forms reviewed. An inventory of 20 items with a set of instructions and response- and computational-conventions is proposed and the results obtained from a young adult population numbering some 1100 individuals are reported. The separate items are examined from the point of view of sex, cultural and socio-economic factors which might appertain to them and also of their inter-relationship to each other and to the measure computed from them all. Criteria derived from these considerations are then applied to eliminate 10 of the original 20 items and the results recomputed to provide frequency-distribution and cumulative frequency functions and a revised item-analysis. The difference of incidence of handedness between the sexes is discussed.
This review discusses the effects, in the aerospace environment, of alterations in approximately 24-h periodicities (circadian rhythms) upon physiological and psychological functions and possible therapies for desynchronosis induced by such alterations. The consequences of circadian rhythm alteration resulting from shift work, transmeridian flight, or altered day lengths are known as desynchronosis, dysrhythmia, dyschrony, jet lag, or jet syndrome. Considerable attention is focused on the ability to operate jet aircraft and manned space vehicles. The importance of environmental cues, such as light-dark cycles, which influence physiological and psychological rhythms is discussed. A section on mathematical models is presented to enable selection and verification of appropriate preventive and corrective measures and to better understand the problem of dysrhythmia.
Two processes play a dominant role in sleep regulation: a sleep-dependent process (Process S) and a sleep-independent circadian process (Process C). The time course of Process S was derived from the spectral analysis of slow wave activity in the human EEG. Its level shows an exponential decline during sleep and an increase during waking. The level of Process S at sleep onset is therefore a function of prior waking time. Process C is reflected by the rhythmic variation of sleep propensity during prolonged sleep deprivation, and is assumed to be controlled by a circadian oscillator. In the model, sleep propensity and the duration of sleep are determined by the combined action of the two processes. The model is able to simulate the variations of sleep duration as a function of sleep onset time. Since the amount of REM sleep is little influenced by prior sleep or waking and shows a marked circadian rhythmicity, it is assumed to reflect largely the level of Process C. The cyclic alternation of nonREM and REM sleep is assumed to result from a reciprocal interaction between the two sleep states. In contrast to previous models, only a single circadian oscillator is required to account for the sleep-wake cycle and the sleep organization under entrained and non-entrained schedules. The model also encompasses sleep regulation in animals and may provide indications as to the phylogenetic origin of sleep.
The diagonal and off-diagonal elements of the effective self-diffusion tensor, Deff, are related to the echo intensity in an NMR spin-echo experiment. This relationship is used to design experiments from which Deff is estimated. This estimate is validated using isotropic and anisotropic media, i.e., water and skeletal muscle. It is shown that significant errors are made in diffusion NMR spectroscopy and imaging of anisotropic skeletal muscle when off-diagonal elements of Deff are ignored, most notably the loss of information needed to determine fiber orientation. Estimation of Deff provides the theoretical basis for a new MRI modality, diffusion tensor imaging, which provides information about tissue microstructure and its physiologic state not contained in scalar quantities such as T1, T2, proton density, or the scalar apparent diffusion constant.
This paper analyses the influence of and possible interaction between chronotype (Morning-types, Neither-types and Evening-types) and personality dimensions (neuroticism, extroversion and psychoticism) in the daily consumption of alcohol and psychostimulants (nicotine and caffeine). In a sample of 537 subjects (257 men and 280 women), who were students and professionals with different but fixed work schedules, there were significant differences among the chronotypes regarding the consumption of all the above. Evening-types consumed more alcohol, nicotine and caffeine (coffee and cola), while Morning-types consumed more caffeine from tea. Personality was only related to the consumption of cola: the greater the neuroticism the higher the consumption of this beverage. Stimulant drinks showed various types of interaction with personality types, which revealed a complex pattern of group action. The results stress the need to consider chronotype as a contributory psychological factor in a multi-causal model of consumption of psychoactive substances.
In dealing with inter-individual phase differences in overt circadian rhythms, it is often difficult to distinguish the impact of the endogenous circadian oscillator from that of an individual's habitual lifestyle. In an attempt to resolve this uncertainty about the role of masking influences, two groups of subjects, morning-type and evening-types, were selected and monitored during entrained, habitual sleep-wake conditions and during 24 h of controlled wakefulness in a laboratory-based constant-routine procedure. Under both conditions significant differences were observed in the circadian phases of body temperature and subjective alertness. During constant routine mean between-group differences for these two variables were 2.21 and 4.28 h, respectively. Thus, evidence is provided for the endogenous nature of morningness-eveningness.
A diary-based instrument-the Social Rhythm Metric (SRM)-was used to assess the level of stability of daily social and behavioral rhythms in a group of 239 healthy subjects (112 male, 127 female) ranging in age from 20 to 89 years. Each subject completed the instrument for two consecutive weeks, which were averaged to yield one measure (SRM score) of life-style regularity [range 0 (least regular) to 7 (most regular)] and another of activity level index (ALI), corresponding to the number of (diary listed) activities done per week (max. = 119). SRM score increased reliably with age group at an average rate of 0.018 units per year. ALI showed an "inverted U"-shaped function with a maximum at about 50 years. SRM changes appeared not to be related to demographic differences between the age groups, although ALI differences may have been so related. No main effects or interactions were found with gender. Life-style regularity appears to increase over the life span in response to both biological and psychosocial changes and may represent an adaptation to age-related changes in the circadian system's sensitivity to entraining agents. Regular behavioral rhythms may be conducive to continued good health and well-being.
A single nucleotide polymorphism located in the 3' flanking region of the human CLOCK gene was investigated as a predictor of diurnal preference in a population-based random sample of 410 normal adults. Morningness-eveningness preferences were determined using the 19-item Home-Ostberg questionnaire. Subjects carrying one of the two CLOCK alleles, 3111C, had a significantly lower mean Horne-Ostberg score. The distribution of scores was clearly shifted toward eveningness for these subjects. The score difference was independent of age, sex and ethnic heritage, thus making population stratification effects unlikely to explain this difference. These subjects had a substantial 10- to 44-minute delay in preferred timing for activity or sleep episodes. We suggest that the identified polymorphism or another tightly linked polymorphism within the CLOCK gene or its regulatory elements may be responsible for the finding.
The purpose of this study was to determine, in a large sample of adults of all ages (17-80 years), the effect of morningness/eveningness on sleep/wake schedules, sleep needs, sleep hygiene and subjective daytime somnolence. A total of 617 subjects (219 subjects per chronotype group) matched for age, sex and employment status, completed an abridged morningness/eveningness questionnaire, a questionnaire on sleep habits and the quality of sleep, and the Epworth Sleepiness Scale. Eveningness was associated with a greater need for sleep, less time in bed during the week compared to ideal sleep needs, more time in bed at the weekend, a later bedtime and waking-up time especially at the weekend, more irregular sleep/wake habits and greater caffeine consumption. These subjects built up a sleep debt during the week and extended their duration of sleep at the weekend. They did not, however, rate themselves more sleepy than other types, despite the fact that our results showed a clear link between subjectively evaluated daytime somnolence and sleep debt. Why they were less affected by sleep deprivation is not clear. This raises the question of individual susceptibility to the modification of sleep parameters.
Despite numerous technical treatments in many venues, analysis of covariance (ANCOVA) remains a widely misused approach to dealing with substantive group differences on potential covariates, particularly in psychopathology research. Published articles reach unfounded conclusions, and some statistics texts neglect the issue. The problem with ANCOVA in such cases is reviewed. In many cases, there is no means of achieving the superficially appealing goal of "correcting" or "controlling for" real group differences on a potential covariate. In hopes of curtailing misuse of ANCOVA and promoting appropriate use, a nontechnical discussion is provided, emphasizing a substantive confound rarely articulated in textbooks and other general presentations, to complement the mathematical critiques already available. Some alternatives are discussed for contexts in which ANCOVA is inappropriate or questionable.
Despite markedly different clinical presentations, few studies have reported differences in neuropsychological functioning between mania and depression. Recent work has suggested that differences may emerge on cognitive tasks requiring affective processing, such as decision-making. The present study sought to compare decision-making cognition in mania and depression in order to clarify the current profiles of impairment for these disorders and to contribute to our more general understanding of the relationship between mood and cognition.
Medicated manic patients, depressed patients, and normal healthy controls completed a computerized decision-making task. All subjects were asked to win as many points as possible by choosing outcomes based on variably-weighted probabilities and by placing 'bets' on each decision.
Both patient groups were impaired on this task, as evidenced by slower deliberation times, a failure to accumulate as many points as controls and suboptimal betting strategies. Manic, but not depressed, patients made suboptimal decisions--an impairment that correlated with the severity of their illness.
These findings are consistent with a growing consensus that manic and depressed patients are characterized by significant impairments in cognitive and particularly executive, functioning. Furthermore, the distinct patterns of observed impairment in manic and depressed patients suggests that the nature and extent of cognitive impairment differ between these two groups. Viewed in the context of other recent studies, these findings are consistent with a role for the ventromedial prefrontal cortex in mediating mood-cognition relationships.
Time-zone travelers encounter a pattern of light and darkness, and their endogenous circadian rhythms adapt to the new external time cue until both timing systems synchronize1, but the long-term repeated disturbance of synchronization between the two timing systems impairs physiological and psychological health and induces stress2. Salivary cortisol levels in cabin crew after repeated exposure to jet lag were significantly higher than after short distance flights3, and the higher cortisol levels were associated with cognitive deficits that were dependent on non-semantic stimuli3. The present study demonstrates that significant prolonged cortisol elevations produce reduced temporal lobe volume and deficits in spatial learning and memory; these cognitive deficits became apparent after five years of exposure to high cortisol levels.
The aim of this study was to determine the relationship between circadian preferences, regularity of sleep patterns, sleep problems, daytime sleepiness and daytime behaviour. As a part of an epidemiological survey on sleep in a representative sample of Italian high-school students, a total of 6631 adolescents, aged 14.1-18.6 years, completed the School Sleep Habits Survey, a comprehensive questionnaire including items regarding sleep, sleepiness, substance use, anxiety and depressed mood, use of sleeping pills, school attendance and a morningness/eveningness scale. The sample consisted of 742 evening-types (315 males and 427 females; mean age 17.1 years) and 1005 morning-types (451 males and 554 females; mean age 16.8 years). No significant sex differences were found for morningness/eveningness score. Eveningness was associated with later bedtime and wake-up time, especially on weekends, shorter time in bed during the week, longer weekend time in bed, irregular sleep-wake schedule, subjective poor sleep. Moreover, evening types used to nap more frequently during school days, complained of daytime sleepiness, referred more attention problems, poor school achievement, more injuries and were more emotionally upset than the other chronotype. They referred also greater caffeine-containing beverages and substances to promote sleep consumption. Our results suggest that circadian preference might be related not only to sleep pattern, but also to other adolescent behaviours.
An automated method for segmenting magnetic resonance head images into brain and non-brain has been developed. It is very robust and accurate and has been tested on thousands of data sets from a wide variety of scanners and taken with a wide variety of MR sequences. The method, Brain Extraction Tool (BET), uses a deformable model that evolves to fit the brain's surface by the application of a set of locally adaptive model forces. The method is very fast and requires no preregistration or other pre-processing before being applied. We describe the new method and give examples of results and the results of extensive quantitative testing against "gold-standard" hand segmentations, and two other popular automated methods.
This study tested the hypothesis that microstructural abnormalities in white matter areas of the brain containing frontostriatal tracts are associated with a low rate of remission of geriatric depression.
Thirteen older patients with major depression received open, but controlled, treatment with citalopram at a target daily dose of 40 mg for 12 weeks. Diffusion tensor imaging was used to determine fractional anisotropy in preselected white matter regions.
Survival analysis with Cox's proportional hazards model revealed that lower fractional anisotropy of the right and the left frontal white matter regions 15 mm above the anterior commissure-posterior commissure plane was associated with a low remission rate after age was considered. Remission was not significantly associated with fractional anisotropy of lower frontal regions or a temporal region.
Microstructural white matter abnormalities lateral to the anterior cingulate may be associated with a low rate of remission of geriatric depression.
This study was conducted to further examine the hypothesis of abnormalities in size of corpus callosum in subjects with bipolar disorder.
Sixteen right-handed DSM-IV bipolar I patients and 27 right-handed healthy control subjects were studied. A 1.5-T GE Signa magnet was used, and three-dimensional gradient echo imaging (spoiled gradient recall acquisition) was conducted. Area measurements of corpus callosum were obtained blindly, with a semi-automated software, by a well-trained rater.
Right-handed bipolar I patients had significantly smaller total corpus callosum, genu, posterior body, and isthmus areas compared with right-handed healthy control subjects (analysis of covariance with age, gender, and intracranial volume as covariates, p <.05). Partial correlation analyses, controlled for intracranial volumes, found a significant inverse relationship between age and total callosal, genu, anterior body, isthmus, and circularity in healthy control subjects (p <.05) but not in bipolar patients (p >.05).
Smaller callosal areas may lead to altered inter-hemispheric communication and be involved in the pathophysiology and cognitive impairment found in bipolar disorder.