[show abstract][hide abstract] ABSTRACT: Adults with schizophrenia present cognitive impairments, as do individuals at ultra-high risk for the disorder, youth with relatives with schizophrenia spectrum disorders, and children with antecedents of schizophrenia. The present study aimed to determine if impairments in childhood differed depending on the definition of risk and/or on the degree of relatedness to an affected individual, and if impairments were explained by IQ. Four groups of children aged 9-12 years were studied: (1) 13 children with ≥1 first-degree or ≥2 second-degree affected relatives (high familial loading: FHx(H)); (2) 14 with ≥1 affected second-degree relative (lower familial loading: FHx(L)); (3) 32 with well-replicated antecedents of schizophrenia (ASz); and (4) 45 typically-developing (TD) children with neither a positive family history nor antecedents. Compared to TD children, both FHx(H) and ASz children exhibited significantly poorer verbal comprehension, scholastic achievement, and verbal working memory, while FHx(H) children additionally displayed significantly lower full-scale IQ, and verbal memory and executive function impairments. After adjusting statistical analyses for IQ, group differences were attenuated. Relative to TD children, FHx(L) children showed no significant differences in performance. The results imply that impairments in verbal comprehension, scholastic achievement, and verbal working memory may index vulnerability for schizophrenia among children with affected relatives with the disorder and among those with multiple antecedents of the disorder who have no affected relatives. More accurate identification of children at-risk for schizophrenia and the specific deficits that they present provides opportunities for interventions such as cognitive remediation that may impact the development of the illness.
Journal of psychiatric research 12/2013; · 3.72 Impact Factor
[show abstract][hide abstract] ABSTRACT: Hoarding disorder is typified by persistent difficulties discarding possessions, resulting in significant clutter that obstructs the individual's living environment and produces considerable functional impairment. The prevalence of hoarding disorder, as defined in DSM-5, is currently unknown.
To provide a prevalence estimate specific to DSM-5 hoarding disorder and to delineate the demographic, behavioural and health features that characterise individuals with the disorder.
We conducted a two-wave epidemiological study of 1698 adult individuals, originally recruited via the South East London Community Health (SELCoH) study. Participants screening positively for hoarding difficulties in wave 1, and who agreed to be re-contacted for wave 2 (n = 99), underwent in-home psychiatric interviews and completed a battery of self-report questionnaires. Current DSM-5 diagnoses were made via consensus diagnostic procedure.
In total, 19 individuals met DSM-5 criteria for hoarding disorder at the time of interview, corresponding to a weighted prevalence of 1.5% (95% CI 0.7-2.2). Those with hoarding disorder were older and more often unmarried (67%). Members of this group were also more likely to be impaired by a current physical health condition (52.6%) or comorbid mental disorder (58%), and to claim benefits as a result of these issues (47.4%). Individuals with hoarding disorder were also more likely to report lifetime use of mental health services, although access in the past year was less frequent.
With a lower-bound prevalence of approximately 1.5%, hoarding disorder presents as a condition that affects people of both genders and is associated with substantial adversity.
The British journal of psychiatry: the journal of mental science 10/2013; · 6.62 Impact Factor
[show abstract][hide abstract] ABSTRACT: IMPORTANCE Most case reports suggest an association between autistic spectrum disorders (ASDs) and celiac disease (CD) or positive CD serologic test results, but larger studies are contradictory. OBJECTIVE To examine the association between ASDs and CD according to small intestinal histopathologic findings. DESIGN AND SETTING Nationwide case-control study in Sweden. MAIN OUTCOMES AND MEASURES Through 28 Swedish biopsy registers, we collected data about 26 995 individuals with CD (equal to villous atrophy, Marsh stage 3), 12 304 individuals with inflammation (Marsh stages 1-2), and 3719 individuals with normal mucosa (Marsh stage 0) but positive CD serologic test results (IgA/IgG gliadin, endomysium, or tissue transglutaminase) and compared them with 213 208 age- and sex-matched controls. Conditional logistic regression estimated odds ratios (ORs) for having a prior diagnosis of an ASD according to the Swedish National Patient Register. In another analysis, we used the Cox proportional hazards regression model to estimate hazard ratios (HRs) for future ASDs in individuals undergoing small intestinal biopsy. RESULTS A prior ASD was not associated with CD (OR, 0.93; 95% CI, 0.51-1.68) or inflammation (OR 1.03; 95% CI, 0.40-2.64) but was associated with a markedly increased risk of having a normal mucosa but a positive CD serologic test result (OR, 4.57; 95% CI, 1.58-13.22). Restricting our data to individuals without a diagnosis of an ASD at the time of biopsy, CD (HR, 1.39; 95% CI, 1.13-1.71) and inflammation (HR, 2.01; 95% CI, 1.29-3.13) were both associated with moderate excess risks of later ASDs, whereas the HR for later ASDs in individuals with normal mucosa but positive CD serologic test results was 3.09 (95% CI, 1.99-4.80). CONCLUSIONS AND RELEVANCE Although this study found no association between CD or inflammation and earlier ASDs, there was a markedly increased risk of ASDs in individuals with normal mucosa but a positive CD serologic test result.
[show abstract][hide abstract] ABSTRACT: To investigate the relationship between preterm birth, adolescent, and adult psychosocial outcomes, and alterations in gray matter volume.
Individuals (n = 73) born at <33 weeks of gestation (very preterm) and 49 controls completed the Child Behavior Checklist (CBCL) at age 15 years to identify 'social immaturity' (SI) cases. Voxel-based morphometry was used to investigate gray matter volumes according to CBCL-SI 'caseness.' The Clinical Interview Schedule-Revised (CIS-R) was administered at age 19 years.
Very preterm adolescents were almost 4 times more likely to reach CBCL-SI 'caseness' compared with controls. Ex-preterm SI 'cases' had increased gray matter volume in the fusiform gyrus bilaterally (Talairach coordinates: x = 60, y = -27, z = -30; Z = 3.78; x = -61, y = -35, z = -27; Z = 3.56, after correction for multiple comparisons) compared with ex-preterm SI 'noncases.' Left fusiform volume displayed a stronger correlation with ipsilateral orbitofrontal cortex in SI 'cases' (x = -15, y = 22, z = -26; Z = 3.64). CIS-R total scores were slightly higher in ex-preterm individuals compared with controls. In the whole sample, SI 'cases' in midadolescence also had higher CIS-R scores in adulthood compared with 'noncases' (SI 'cases': mean = 5.7, 95% CI = 4.0-7.4; SI 'noncases': mean = 2.7, 95% CI = 1.1-4.3; F = 6.4, df = 74; P = .013).
Ex-preterm adolescents had increased socialization problems in adolescence, which were associated with volumetric alterations in an emotion-processing brain network. Atypical social development is linked to an increased vulnerability to psychiatric disorder.
The Journal of pediatrics 09/2013; · 4.02 Impact Factor
[show abstract][hide abstract] ABSTRACT: OBJECTIVE Despite the widespread belief that neuropsychological decline is a cardinal feature of the progression from the premorbid stage to the chronic form of schizophrenia, few longitudinal studies have examined change in neuropsychological functioning from before to after illness onset. The authors examined whether neuropsychological decline is unique to schizophrenia, whether it is generalized or confined to particular mental functions, and whether individuals with schizophrenia also have cognitive problems in everyday life. METHOD Participants were members of a representative cohort of 1,037 individuals born in Dunedin, New Zealand, in 1972 and 1973 and followed prospectively to age 38, with 95% retention. Assessment of IQ and specific neuropsychological functions was conducted at ages 7, 9, 11, and 13, and again at age 38. Informants also reported on any cognitive problems at age 38. RESULTS Individuals with schizophrenia exhibited declines in IQ and in a range of mental functions, particularly those tapping processing speed, learning, executive function, and motor function. There was little evidence of decline in verbal abilities or delayed memory, however, and the developmental progression of deficits in schizophrenia differed across mental functions. Processing speed deficits increased gradually from childhood to beyond the early teen years, whereas verbal deficits emerged early but remained static thereafter. Neuropsychological decline was specific to schizophrenia, as no evidence of decline was apparent among individuals with persistent depression, children with mild cognitive impairment, individuals matched on childhood risk factors for schizophrenia, and psychiatrically healthy individuals. Informants also noticed more cognitive problems in individuals with schizophrenia. CONCLUSIONS There is substantial neuropsychological decline in schizophrenia from the premorbid to the postonset period, but the extent and developmental progression of decline varies across mental functions. Findings suggest that different pathophysiological mechanisms may underlie deficits in different mental functions.
American Journal of Psychiatry 09/2013; · 14.72 Impact Factor
[show abstract][hide abstract] ABSTRACT: A number of studies have reported that patients with psychosis who use cannabis have better cognitive performance than those who do not. This is surprising as cannabis can impair cognition in healthy subjects. An obvious question is whether the better current performance of psychotic patients who have used cannabis is a reflection of their having a higher premorbid IQ than those psychotic patients who haven't used cannabis.
In a sample of patients at their first episode of psychosis, we tested the hypothesis that patients who smoked cannabis would have a higher premorbid IQ than patients who did not.
279 participants (119 patients and 160 healthy controls) were assessed in order to obtain current and premorbid IQ measures and detailed information on cannabis use. We examined the association between cannabis use and both premorbid and current IQ in patients and controls.
Patients who had ever smoked cannabis had significantly higher current (p<.001) and premorbid IQ (p=.004) compared to patients who had never used cannabis. This difference was not found among controls.
These findings suggest that the better cognitive performance of patients with their first episode of psychosis who have used cannabis compared with those who haven't is due to the better premorbid IQ of the former.
Schizophrenia Research 08/2013; · 4.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: IMPORTANCE Between 1978 and 2010, approximately 5 million infants were born after in vitro fertilization (IVF) treatments. Yet limited information on neurodevelopment after IVF exists, especially after the first year of life. OBJECTIVE To examine the association between use of any IVF and different IVF procedures and the risk of autistic disorder and mental retardation in the offspring. DESIGN, SETTING, AND PARTICIPANTS A population-based, prospective cohort study using Swedish national health registers. Offspring born between 1982 and 2007 were followed up for a clinical diagnosis of autistic disorder or mental retardation until December 31, 2009. The exposure of interest was IVF, categorized according to whether intracytoplasmic sperm injection (ICSI) for male infertility was used and whether embryos were fresh or frozen. For ICSI, whether sperm were ejaculated or surgically extracted was also considered. MAIN OUTCOMES AND MEASURES Relative risks (RRs) for autistic disorder and mental retardation and rates per 100 000 person-years, comparing spontaneously conceived offspring with those born after an IVF procedure and comparing 5 IVF procedures used in Sweden vs IVF without ICSI with fresh embryo transfer, the most common treatment. We also analyzed the subgroup restricted to singletons. RESULTS Of the more than 2.5 million infants born, 30 959 (1.2%) were conceived by IVF and were followed up for a mean 10 (SD, 6) years. Overall, 103 of 6959 children (1.5%) with autistic disorder and 180 of 15 830 (1.1%) with mental retardation were conceived by IVF. The RR for autistic disorder after any procedure compared with spontaneous conception was 1.14 (95% CI, 0.94-1.39; 19.0 vs 15.6 per 100 000 person-years). The RR for mental retardation was 1.18 (95% CI, 1.01-1.36; 46.3 vs 39.8 per 100 000 person-years). For both outcomes, there was no statistically significant association when restricting analysis to singletons. Compared with IVF without ICSI with fresh embryo transfer, there were statistically significantly increased risks of autistic disorder following ICSI using surgically extracted sperm and fresh embryos (RR, 4.60 [95% CI, 2.14-9.88]; 135.7 vs 29.3 per 100 000 person-years); for mental retardation following ICSI using surgically extracted sperm and fresh embryos (RR, 2.35 [95% CI, 1.01-5.45]; 144.1 vs 60.8 per 100 000 person-years); and following ICSI using ejaculated sperm and fresh embryos (RR, 1.47 [95% CI, 1.03-2.09]; 90.6 vs 60.8 per 100 000 person-years). When restricting the analysis to singletons, the risks of autistic disorder associated with ICSI using surgically extracted sperm were not statistically significant, but the risks associated with ICSI using frozen embryos were significant for mental retardation (with frozen embryos, RR, 2.36 [95% CI, 1.04-5.36], 118.4 vs 50.6 per 100 000 person-years]; with fresh embryos, RR, 1.60 [95% CI, 1.00-2.57], 80.0 vs 50.6 per 100 000 person-years). CONCLUSIONS AND RELEVANCE Compared with spontaneous conception, IVF treatment overall was not associated with autistic disorder but was associated with a small but statistically significantly increased risk of mental retardation. For specific procedures, IVF with ICSI for paternal infertility was associated with a small increase in the RR for autistic disorder and mental retardation compared with IVF without ICSI. The prevalence of these disorders was low, and the increase in absolute risk associated with IVF was small.
JAMA The Journal of the American Medical Association 07/2013; 310(1):75-84. · 29.98 Impact Factor
[show abstract][hide abstract] ABSTRACT: Context:Cross-sectional studies of the signs and symptoms of psychosis yield dimensional phenotypes. However, the validity and clinical utility of such dimensions remain debated. This study investigated the structure of psychotic symptomatology, the stability of the structure over time, and the concordance between symptom dimensions and categorical diagnoses.Methods:Sample consisted of 500 first-episode psychotic patients. A cross-sectional study (N = 500) investigated the organizational structure of symptom dimensions at the onset of psychosis and its concordance with categorical diagnoses; next, a nested longitudinal study (N = 100) examined the stability of the symptom dimensions structure after 5-10 years of follow-up.Results:Factor analyses identified 6 first-order factors (mania, negative, disorganization, depression, hallucinations, and delusions) and 2 high-order factors (affective and nonaffective psychoses). Cumulative variance accounted for by the first and high-order factors was 63%: 31% by the first-order factors and 32% by the high-order factors. The factorial structure of psychotic symptoms during first episode remained stable after 5-10 years of follow-up. The overall concordance between 4 categorical diagnostic groups (schizophrenia, mania with psychosis, psychotic depression and schizoaffective disorder) and dimensional symptom ranged from 62.2% to 73.1% (when the schizoaffective group was excluded).Conclusions:Symptoms of psychosis assume a multidimensional hierarchical structure. This hierarchical model was stable over time and showed good concordance with categorical diagnoses. The combined use of dimensional and categorical approach to psychotic disorders would be of clinical and research utility.
[show abstract][hide abstract] ABSTRACT: The International Collaboration for Autism Registry Epidemiology (iCARE) is the first multinational research consortium (Australia, Denmark, Finland, Israel, Norway, Sweden, USA) to promote research in autism geographical and temporal heterogeneity, phenotype, family and life course patterns, and etiology. iCARE devised solutions to challenges in multinational collaboration concerning data access security, confidentiality and management. Data are obtained by integrating existing national or state-wide, population-based, individual-level data systems and undergo rigorous harmonization and quality control processes. Analyses are performed using database federation via a computational infrastructure with a secure, web-based, interface. iCARE provides a unique, unprecedented resource in autism research that will significantly enhance the ability to detect environmental and genetic contributions to the causes and life course of autism.
Journal of Autism and Developmental Disorders 04/2013; · 3.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: IMPORTANCE Advancing paternal age has been linked to autism. OBJECTIVE To further expand knowledge about the association between paternal age and autism by studying the effect of grandfathers' age on childhood autism. DESIGN Population-based, multigenerational, case-control study. SETTING Nationwide multigeneration and patient registers in Sweden. PARTICIPANTS We conducted a study of individuals born in Sweden since 1932. Parental age at birth was obtained for more than 90% of the cohort. Grandparental age at the time of birth of the parent was obtained for a smaller subset (5936 cases and 30 923 controls). MAIN OUTCOME AND MEASURE International Classification of Diseases diagnosis of childhood autism in the patient registry. RESULTS A statistically significant monotonic association was found between advancing grandpaternal age at the time of birth of the parent and risk of autism in grandchildren. Men who had fathered a daughter when they were 50 years or older were 1.79 times (95% CI, 1.35-2.37; P < .001) more likely to have a grandchild with autism, and men who had fathered a son when they were 50 years or older were 1.67 times (95% CI, 1.35-2.37; P < .001) more likely to have a grandchild with autism, compared with men who had fathered children when they were 20 to 24 years old, after controlling for birth year and sex of the child, age of the spouse, family history of psychiatric disorders, highest family educational level, and residential county. A statistically significant monotonic association was also found between advancing paternal age and risk of autism in the offspring. Sensitivity analyses indicated that these findings were not the result of bias due to missing data on grandparental age. CONCLUSIONS AND RELEVANCE Advanced grandparental age was associated with increased risk of autism, suggesting that risk of autism could develop over generations. The results are consistent with mutations and/or epigenetic alterations associated with advancing paternal age.
[show abstract][hide abstract] ABSTRACT: Patients with schizophrenia and other psychoses exhibit a wide range of neuropsychological deficits. An unresolved question concerns whether there are gender differences in cognitive performance.
Data were derived from a multi-centre population based case-control study of patients with first-episode psychosis. A neuropsychological test battery was administered to patients with a diagnosis of schizophrenia or schizoaffective disorder (N=70, 36% females), bipolar/mania (N=34, 60% females), depressive psychosis (N=36, 58% females) and healthy controls (N=148, 55% females). Generalized and specific cognitive deficits were compared.
There was strong evidence for disorder-specific gender differences in neuropsychological performance. Males and females with schizophrenia showed similar pervasive neuropsychological impairments. In psychotic depressive disorder females performed worse than males across neuropsychological measures. Differences in neuropsychological performance between males and females with bipolar/manic disorder were restricted to language functions. Symptom severity did not contribute to the observed gender differences.
Early in the course of psychotic illness, gender related factors appear to moderate the severity of cognitive deficits in depressive psychosis and bipolar/mania patients.
PLoS ONE 01/2013; 8(10):e77318. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: The Structured Interview for Hoarding Disorder (SIHD) is a semi-structured instrument designed to assist clinicians and trained interviewers with the nuanced diagnosis of hoarding disorder (HD). The manuscript introduces the rationale, development, and design of the SIHD and presents a test of the instrument's inter-rater reliability and convergent/discriminant validity. Ninety-nine individuals with self-reported hoarding behavior, originally recruited as part of a large two-wave epidemiological study, were evaluated in their homes using the SIHD. Diagnoses of HD were determined by consensus, following a best estimate diagnosis procedure. To enable the assessment of inter-rater reliability, a psychiatrist with extensive experience diagnosing HD also independently and blindly reviewed each participant's SIHD. In addition, agreement of SIHD diagnoses with those indicated by other screening instruments for HD and depression were examined. Results indicate “substantial” or “near perfect” inter-rater reliability for all core HD criteria and specifiers. Convergent and discriminant validity were, furthermore, excellent. Overall, the SIHD offers an intuitive, valid, and reliable means of diagnosing HD. The interview also facilitates the assessment of other relevant features, such as risk. We offer recommendations for its use in both research and clinical settings, as well as suggestions for the training of interviewers.
Journal of Obsessive-Compulsive and Related Disorders. 01/2013; 2(3):346–350.
[show abstract][hide abstract] ABSTRACT: Early identification of Bipolar Disorder (BD) remains poor despite the high levels of disability associated with the disorder.
We developed and evaluated a new DSM orientated scale for the identification of young people at risk for BD based on the Child Behavior Checklist (CBCL) and compared its performance against the CBCL-Pediatric Bipolar Disorder (CBCL-PBD) and the CBCL-Externalizing Scale, the two most widely used scales.
The new scale, CBCL-Mania Scale (CBCL-MS), comprises 19 CBCL items that directly correspond to operational criteria for mania. We tested the reliability, longitudinal stability and diagnostic accuracy of the CBCL-MS on data from the TRacking Adolescents' Individual Lives Survey (TRAILS), a prospective epidemiological cohort study of 2230 Dutch youths assessed with the CBCL at ages 11, 13 and 16. At age 19 lifetime psychiatric diagnoses were ascertained with the Composite International Diagnostic Interview. We compared the predictive ability of the CBCL-MS against the CBCL-Externalising Scale and the CBCL-PBD in the TRAILS sample.
The CBCL-MS had high internal consistency and satisfactory accuracy (area under the curve = 0.64) in this general population sample. Principal Component Analyses, followed by parallel analyses and confirmatory factor analyses, identified four factors corresponding to distractibility/disinhibition, psychosis, increased libido and disrupted sleep. This factor structure remained stable across all assessment ages. Logistic regression analyses showed that the CBCL-MS had significantly higher predictive ability than both the other scales.
Our data demonstrate that the CBCL-MS is a promising screening instrument for BD. The factor structure of the CBCL-MS showed remarkable temporal stability between late childhood and early adulthood suggesting that it maps on to meaningful developmental dimensions of liability to BD.
PLoS ONE 01/2013; 8(8):e69459. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background. The potential inclusion of cognitive assessments in the DSM-V and large time-consuming assessments drive a need for short tests of cognitive impairments. We examined the reliability and validity of a brief, 15-minute, version of the Wechsler Adult Intelligence Scale-III (WAIS-III). Methods. The sample consisted of patients diagnosed with schizophrenia (n=75), their siblings without schizophrenia (n=74) and unrelated healthy controls (n=84). A short WAIS-III consists of the Digit Symbol Coding subtest, and every second (or third) item of Block Design, Information, and Arithmetic. Psychometric analyses were implemented using item-response theory (IRT) to determine the best minimal item short version, while maintaining the sensitivity and reliability of the IQ score. Results. The proposed 15-minute WAIS-III gave reliable estimates of the Full Scale IQ (FSIQ) in all three groups in the sample. The 15-minute (select-item) version yielded an overall R of.95 (R (2)=.92) and IRT yielded an R of .96 (R (2)=.92). All four subtests performed well in differentiating patients, relatives, and healthy controls. Multivariate analysis showed a significant difference in FSIQ-estimate between patients, relatives, and healthy controls, F(2, 202) = 19.00, p < .0001. Regression modelling showed that the three versions of the WAIS had similar associations with functional outcome after a 3-year follow-up. Conclusions. Our proposed 15-minute version of the WAIS may serve as a useful screening device for general intellectual ability in research or clinical settings, and is recommended when a quick and accurate IQ estimate is desired.
[show abstract][hide abstract] ABSTRACT: Psychiatric epidemiology has made significant contributions to the identification of risk factors for mental disorders. Available evidence underscores the complexity of the interactions between risk and disease and highlights conceptual and methodological challenges particularly in examining risk and disease relations beyond the level of simple associations. We propose that a life course approach in the study of risk factors for mental disorders, combined with fast developing analytical statistical tools, is the most promising avenue towards shifting the focus of the field from associations to generating and testing aetiological hypotheses. This paper presents the basic tenants of life course risk modelling, highlights key examples in the available literature that demonstrate the potential of this approach to advance our understanding of the trajectories from risk to disease and discusses priorities for future research.
[show abstract][hide abstract] ABSTRACT: The minor neurological and cognitive deficits consistently reported in psychoses may reflect the same underlying brain dysfunction. Still, even in healthy individuals minor neurological abnormalities are associated with worse cognitive function. Therefore, establishing which neurological and cognitive deficits are specific to psychosis is essential to inform the pathophysiology of this disorder. We evaluated a large epidemiological sample of patients with first episode psychosis (n=242) and a population-based sample of healthy individuals (n=155), as part of the AESOP study. We examined neurological soft signs using the Neurological Evaluation Scale (Buchanan and Heinrichs, 1989), and generalized and specific cognitive deficits (memory; verbal abilities; attention, concentration and mental speed; executive functions and working memory; language; visual constructual/perceptual abilities). In patients, more neurological signs across all subscales were associated with worse general cognitive function, while in controls this was only present for sensory integration and sequencing signs. Furthermore, in patients, but not in healthy individuals, more sensory integrative signs were associated with deficits in specific cognitive domains, such as memory, verbal abilities, language, visual/perceptual, executive function (p ranging <0.001-0.002); sequencing signs with language, executive function, and attention (p<0.001-0.004); and motor signs with poorer verbal abilities (p=0.001). These findings indicate the presence of specific associations between neurological and cognitive deficits in psychosis that are distinct from those of healthy individuals.
Schizophrenia Research 10/2012; · 4.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: BACKGROUND: Recent research has identified impairment in processing speed, measured by the digit-symbol substitution task, as central to the cognitive deficit in schizophrenia. However, the underlying cognitive correlates of this impairment remain unknown. METHODS: A sample of cases (N=125) meeting DSM-IV criteria for schizophrenia and a sample of community controls (N=272) from the same geographical area completed a set of putative measures of processing-speed ability to which we implemented confirmatory factor and structural regression modelling in order to elucidate the latent structure of processing speed. Next, we tested the degree to which the structural and relational portions of the model were equal across groups. RESULTS: Processing-speed ability was best defined, in both controls and cases (χ(2)=38.59(26), p=0.053), as a multidimensional cognitive ability consisting of three latent factors comprising: psychomotor speed, sequencing and shifting, and verbal fluency. However, cases exhibited dedifferentiation (i.e., markedly stronger inter-correlations between factors; χ(2)=59.94(29), p<.01) and a reliance on an alternative ensemble of cognitive operations to controls when completing the digit-symbol substitution task. CONCLUSION: Dedifferentiation of processing-speed ability in schizophrenia and subsequent overreliance on alternative (and possibly less than optimal) cognitive operations underlies the marked deficit observed on the digit-symbol substitution task.
Schizophrenia Research 10/2012; · 4.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: Associations between symptom dimensions and cognition have been mainly studied in non-affective psychosis. The present study investigated whether previously reported associations between cognition and four symptom dimensions (reality distortion, negative symptoms, disorganisation and depression) in non-affective psychosis generalise to a wider spectrum of psychoses. It also extended the research focus to mania, a less studied symptom dimension.
Linear and non-linear (quadratic, curvilinear or inverted-U-shaped) associations between cognition and the above five symptom dimensions were examined in a population-based cohort of 166 patients with first-onset psychosis using regression analyses.
Negative symptoms showed statistically significant linear associations with IQ and processing speed, and a significant curvilinear association with verbal memory/learning. Significant quadratic associations emerged between mania and processing speed and mania and executive function. The contributions of mania and negative symptoms to processing speed were independent of each other. The findings did not differ between affective and non-affective psychoses, and survived correction for multiple testing.
Mania and negative symptoms are associated with distinct patterns of cerebral dysfunction in first-onset psychosis. A novel finding is that mania relates to cognitive performance by a complex response function (inverted-U-shaped relationship). The associations of negative symptoms with cognition include both linear and quadratic elements, suggesting that this dimension is not a unitary concept. These findings cut across affective and non-affective psychoses, suggesting that different diagnostic entities within the psychosis spectrum lie on a neurobiological continuum.
Schizophrenia Research 07/2012; 140(1-3):221-31. · 4.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: CONTEXT The clinical and etiologic relation between autism spectrum disorders (ASDs) and schizophrenia is unclear. The degree to which these disorders share a basis in etiology has important implications for clinicians, researchers, and those affected by the disorders. OBJECTIVE To determine whether a family history of schizophrenia and/or bipolar disorder is a risk factor for ASD. DESIGN, SETTING, AND PARTICIPANTS We conducted a case-control evaluation of histories of schizophrenia or bipolar disorder in first-degree relatives of probands in 3 samples-population registers in Sweden, Stockholm County (in Sweden), and Israel. Probands met criteria for ASD, and affection status of parents and siblings for schizophrenia and bipolar disorder were established. RESULTS The presence of schizophrenia in parents was associated with an increased risk for ASD in a Swedish national cohort (odds ratio [OR], 2.9; 95% CI, 2.5-3.4) and a Stockholm County cohort (OR, 2.9; 95% CI, 2.0-4.1). Similarly, schizophrenia in a sibling was associated with an increased risk for ASD in a Swedish national cohort (OR, 2.6; 95% CI, 2.0-3.2) and an Israeli conscription cohort (OR, 12.1; 95% CI, 4.5-32.0). Bipolar disorder showed a similar pattern of associations but of lesser magnitude. CONCLUSIONS Findings from these 3 registers along with consistent findings from a similar study in Denmark suggest that ASD, schizophrenia, and bipolar disorder share common etiologic factors.
Archives of general psychiatry 07/2012; · 12.26 Impact Factor