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

Department of Psychiatry and Psychotherapy, Freiburg University Medical Center, Hauptstr. 5, D-79104 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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    • "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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    • "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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    • "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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