Late-onset major depression is thought to have a biological (vascular) basis, which could be a result of brain structure change. Vascular lesions can affect both the gray matter (GM) and white matter (WM), while most previous studies addressed WM abnormality. This study explored the disease- and symptom (history of suicide attempt) -related GM morphometry in elderly male patients with late-onset depression. A total of 70 patients with depression admitted to our geriatric psychiatric ward were investigated, and 26 age-matched males were recruited as controls. We used T1-weighted magnetic resonance imaging (MRI) to obtain cerebral structural information and adopted voxel-based morphometry (VBM) to investigate brain volume change related to disease (depression vs control) and symptom (depression with history of suicide attempt vs depression without history of suicide attempt). Late-onset depression was associated with smaller volumes in several regions of GM (insula and the posterior cingulate region) and WM (subcallosal cingulate cortex, floor of lateral ventricles, parahippocampal region, insula, and the cerebellum). Compared with nonsuicidal counterpart, suicidal depression was associated with decreased GM and WM volume in the frontal, parietal, and temporal regions, and the insula, lentiform nucleus, midbrain, and the cerebellum. Marked regional volume reduction was noticed at dorsal medial prefrontal cortex. Our results demonstrate that the development of suicidal behaviors in major depression is related to widespread but discrete volume reduction in several cortical and subcortical structures, fitting with the hypothesis that decreased cerebral volume in certain regions renders biological susceptibility to attempt suicide during depressive states.

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A common polymorphism of the brain-derived neurotrophic factor (BDNF) gene (Val66Met) has been implicated in anxiety, which is associated with lower vagal activity. We hypothesize that the BDNF Val66Met polymorphism may have a modulatory effect on the cardiac sympathovagal balance. A total of 211 healthy Chinese-Han adults (58 male, 153 female, aged 33.3 +/- 10.3 years) were recruited with three BDNF genotypes: Val/Val (47, 22.3%), Val/Met (108, 51.2%), and Met/Met (56, 26.5%). Autonomic function was assessed via an analysis of heart rate variability. Reductions in high-frequency power, an index for parasympathetic activity, and increases in the low-frequency/high-frequency ratio, an index for sympathovagal balance, were found in subjects bearing the Met/Met genotype as compared to the Val/Val group. These results suggest that an altered sympathovagal balance with relatively decreased parasympathetic activity is associated with the Met/Met genotype, suggesting a potential role for the studied BDNF polymorphism in modulating cardiac autonomic functions.

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