Chronic insomnia and MRI-measured hippocampal volumes: A pilot study

University of Freiburg, Freiburg, Baden-Württemberg, Germany
Sleep (Impact Factor: 4.59). 09/2007; 30(8):955-8.
Source: PubMed


Morphometric analysis of magnetic resonance imaging brain scans was used to investigate possible neuroanatomic differences between patients with primary insomnia compared to good sleepers.
MRI images (1.5 Tesla) of the brain were obtained from insomnia patients and good sleepers. MRI scans were analyzed bilaterally by manual morphometry for different brain areas including hippocampus, amygdala, anterior cingulate, orbitofron-tal and dorsolateral prefrontal cortex.
University Hospital Sleep Center and Radiology Department
8 unmedicated physician-referred patients with chronic primary insomnia (3 males, 5 females; 48.4 + 16.3 years) and 8 good sleepers matched for age, sex, body mass index, and education.
Patients with primary insomnia demonstrated significantly reduced hippocampal volumes bilaterally compared to the good sleepers. None of the other regions of interest analyzed revealed differences between the 2 groups.
These pilot data raise the possibility that chronic insomnia is associated with alterations in brain structure. Replication of the findings in larger samples is needed to confirm the validity of the data. The integration of structural, neuropsychological, neuroendocrine and polysomnographic studies is necessary to further assess the relationships between insomnia and brain function and structure.

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Available from: Dieter Riemann
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    • "The finding that lower levels of self-reported sleep efficiency (i.e., of the time spent in bed, less time is spent actually asleep) was associated with smaller hippocampi is particularly novel, though not surprising given emerging evidence of the critical role of sleep-wake changes to cognition in neurodegenerative disease (see [21]). This finding is also aligned with recent research findings in insomniacs as well as those in healthy older people showing, respectively, that poor sleep is associated with smaller hippocampal volume [35] and spectroscopic markers of glial integrity in the hippocampus [17]. While the precise mechanisms underpinning such relationships are unknown, animal data has shown that sleep is critical for the promotion of neurotrophins and hippocampal neurogenesis, and importantly, that prolonged sleep disruption is associated with substantial (30–80%) decreases in cell proliferation and cell survival to maturation [5]. "
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    ABSTRACT: Background and objectives: Decreased hippocampal volume in older adults is associated with neurodegenerative and psychiatric diseases. Several modifiable risk factors have been associated with the size of this structure, however the relative contribution of these factors to hippocampal atrophy is unclear. This study aimed to examine the relationship between modifiable risk factors and hippocampal volume in older adults at risk of cognitive decline. Methods: Two hundred and eighteen participants (mean age = 67.3 years, MMSE = 28.6) with mood and/or memory complaints underwent clinical and neuropsychological assessment, and magnetic resonance imaging. Measures of depression, global cognitive functioning, exercise, vascular health, cognitive reserve, sleep, and memory were collected. Hippocampal volumes were derived using image segmentation as implemented by FMRIB Software Library. Results: Smaller hippocampal volumes were strongly associated with poorer verbal learning and memory as well as diagnoses of either multiple or amnestic mild cognitive impairment. Based on univariate correlations, multivariable regressions were performed (controlling for age and total intracranial volume) to determine which modifiable risk factors were associated with hippocampal volume. For the left hippocampus, poor sleep efficiency and greater than five years untreated depressive illness remained significant predictors. For the right hippocampus, diabetes and low diastolic blood pressure significant predictors. Conclusions: Although their contribution is small, lower sleep efficiency, low blood pressure, diabetes, and untreated depression are associated with reduced hippocampal volumes. Studies exploring the impact of early intervention for these risk factors on hippocampal integrity are warranted.
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    • "Manual morphometry 20 patients with PI and 15 matched controls No difference in hippocampal size between groups Neylan et al. [37] Manual morphometry Subjective sleep assessment of 17 patients with PTSD and 19 matched controls Worse insomnia correlated with smaller volumes of the CA3 and dentate areas of the hippocampus Altena et al. [33] VBM 24 patients with PI and 13 matched controls No gray matter differences in the area of the hippocampus between groups Riemann et al. [29] "
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    ABSTRACT: Posttraumatic stress disorder (PTSD) is associated with smaller volumes of the hippocampus, as has been demonstrated by meta-analyses. Proposed mechanistic relationships are reviewed briefly, including the hypothesis that sleep disturbances mediate the effects of PTSD on hippocampal volume. Evidence for this includes findings that insomnia and restricted sleep are associated with changes in hippocampal cell regulation and impairments in cognition. We present results of a new study of 187 subjects in whom neither PTSD nor poor sleep was associated with lower hippocampal volume. We outline a broad research agenda centered on the hypothesis that sleep changes mediate the relationship between PTSD and hippocampal volume.
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    • "Furthermore, reduced hippocampal volume [20] and decreased cognitive performance has been found in individuals with chronic insomnia [19]. In the animal literature, prolonged sleep restriction and or fragmentation has been found to reduce hippocampal cell proliferation and neurogenesis [21–24]. Thus, it has been hypothesized that chronically restricted or fragmented sleep may impact the generation and maturation of new neurons in the adult human brain and that the functional consequences and cognitive disturbances associated with chronic sleep disturbance may be related to reductions in neuro-synaptic plasticity and neurogenesis [25]. "
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