Smaller gray matter volume of hippocampus/parahippocampus in elderly people with subthreshold depression: A cross-sectional study

Abstract

Background: Hippocampal/parahippocampal structural changes accompany major depressive disorders in the elderly, but whether subthreshold depression (StD) at an advanced age is also accompanied by similar changes in hippocampal/parahippocampal volumes is still unknown. By using voxel-based morphometry (VBM) analysis of the gray matter, we explored whether there are structural alterations of the hippocampus/parahippocampus and the correlations between its volume and participants' self-reported depressive symptoms. Methods: Participants were 19 community-dwelling older adults with StD assessed by the Center for Epidemiologic Studies Depression scale (CES-D) scores. We collected magnetic resonance images of their brain compared to images of 17 healthy aged-matched adults. We used VBM to analyze differences in gray matter volume (GMV) of the hippocampus/parahippocampus between the two groups. Moreover, we examined the correlation between the GMV of the hippocampus/parahippocampus and participants' self-reported depressive symptoms. Results: VBM revealed that elderly individuals with StD had substantially reduced volumes of the right parahippocampus compared to healthy controls. Furthermore, the volumes of the hippocampus/parahippocampus were significantly associated with participants' self-reported depressive symptoms in StD. Conclusions: Gray matter volume alterations in the hippocampus/parahippocampus are correlated with subthreshold depression suggesting that early structural changes in the hippocampus/parahippocampus can constitute a risk indicator of depression.