Hippocampal total, subregion, and subfield volume alterations in late-life depression.

BACKGROUND: Despite consistent support for smaller total hippocampal volumes in late-life depression (LLD), there is less consensus on LLD's relationship with hippocampal subregions and subfields. This is particularly germane for interactive effects of aging in context of depression, as individuals with LLD may exhibit accelerated aging processes. METHODS: We examined 260 depressed (current and recently remitted) and 140 non-depressed older adults who completed 3T MRI and extracted hippocampal subregion and subfield volumes. Primary analyses investigated effects of LLD diagnosis, depression status, and age of onset on hippocampal volumes. Secondary analyses evaluated interactive effects of age and these diagnostic groupings on hippocampal volumes. RESULTS: Compared to controls, LLD exhibited smaller total hippocampal volumes, with smaller volumes of the bilateral hippocampal head and the right hemisphere body, tail, CA1, and molecular layer. When comparing current and remitted LLD, individuals with current LLD exhibited smaller right total hippocampus, head, body, and molecular layer volumes compared to controls. They also exhibited smaller CA1, CA2, and CA4/dentate gyrus volumes compared to both control and remitted LLD groups. No regions differed between control and remitted LLD groups. We did not observe significant group differences in any volume measure between LLD individuals with an early- or later-life depression onset. There was no significant age by diagnostic group interactions on hippocampal volumes across any analyses. CONCLUSIONS: This cross-sectional work supports diagnostic, but not accelerated aging, effects of depression on hippocampus volumes. In contrast to recently remitted LLD, currently depressed individuals exhibited smaller volumes primarily in the right hippocampus.