Hippocampal subfield volumes associated with depression symptoms in older dementia caregivers

Hippocampal volume reductions are associated with Major Depressive Disorder. Evidence of relationships between hippocampal subfield volumes and specific subsyndromal depression symptoms can add to our understanding of this mechanistic correlate.

Cross-sectional correlational study.

University of Pittsburgh research facilities using 7 Tesla (7 T) MRI.

Sixty older adults (mean age=70.05; standard deviation=6.99) who had stress/strain related to family dementia caregiving and had no more than subsyndromal depression symptoms (PHQ-9 < 10 at screening).

Hippocampal subfield volumes were obtained from 7 T MRI segmentations. Depression symptom outcomes were Center for Epidemiological Studies Scale Revised (CESD-R) total and symptom group scores (assessing symptoms of dysphoria, anhedonia, appetite changes, sleep, thinking/concentration, guilt/worthlessness, tiredness/fatigue, psychomotor disturbance, and suicidal ideation). Partial Spearman correlation coefficients, adjusted for age, sex, and intracranial volume, were used to evaluate associations of subfield volumes with depression symptoms.

Of the five subregion volumes examined, only lower DG volume was statistically associated with higher total CESD-R depression total scores (Spearman r = -0.27, p = 0.04). There were medium effect size correlations of DG volumes with three of the nine symptom groups: thinking/concentration (Spearman r = 0.37, p = 0.004, q=0.04); dysphoria (Spearman r = -0.29, p = 0.02, q=0.07); and tiredness/fatigue (Spearman r = -0.29, p = 0.02, q=0.07).

Finding correlations of low DG volume with subsyndromal depression symptoms raises questions of whether low DG volumes contribute to the etiology and consequences of subsyndromal depression symptoms (such as risk for dementia and major depression). Future studies are needed to replicate/extend these findings and clarify the broader mechanism(s) linking DG structural characteristics with depression.