Hippocampal Total, Subregion, and Subfield Volume Alterations in Late-Life Depression

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 relevant for the interactive effects of aging in the context of depression because individuals with LLD may exhibit accelerated aging processes.

We examined 260 older adults with depression (current and recently remitted) and 140 older adults without depression who completed 3T magnetic resonance imaging, and extracted hippocampal subregion and subfield volumes. Primary analyses investigated the effects of LLD diagnosis, depression status, and age of onset on hippocampal volumes. Secondary analyses evaluated the interactive effects of age and these diagnostic groupings on hippocampal volumes.

Compared with controls, participants with 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 participants with current and remitted LLD, individuals with current LLD exhibited smaller right total hippocampus, head, body, and molecular layer volumes than controls. They also exhibited smaller CA1, CA2, and CA4/dentate gyrus volumes compared with both control and remitted LLD groups. No regions differed between the control and remitted LLD groups. We did not observe significant group differences in any volume measure between individuals with LLD with an early- or later-life depression onset. There were no significant age-by-diagnostic-group interactions on hippocampal volumes in any analyses.

This cross-sectional work supports diagnostic, but not accelerated aging, effects of depression on hippocampus volumes. In contrast to recently remitted LLD, individuals with current depression exhibited smaller volumes primarily in the right hippocampus.