Hippocampal volume and antidepressant response in geriatric depression

Biological markers of treatment response may include structural brain changes seen on neuroimaging. While most imaging studies have focused on cerebrovascular disease, evidence is growing that the hippocampus may play a role in depression, particularly geriatric depression.

We studied 60 depressed elderly patients enrolled in a longitudinal study who were treated with antidepressant medications using a treatment guideline-based approach. Baseline and 12-week Montgomery-Asberg Depression Rating Scale (MADRS) scores were obtained via interview with a geriatric psychiatrist. All subjects had a baseline magnetic resonance imaging (MRI) brain scan. MRI scans were processed using standard protocols to determine total cerebral volume and right and left hippocampal volumes. Hippocampal volumes were standardized for total cerebral volume. MADRS scores less than 10 were used to define remission.

When the group with the lowest quartile of standardized hippocampal volumes was compared to those above the first quartile, those with small right and total hippocampal volumes were less likely to achieve remission. In a subsequent logistic regression model controlling for age small standardized right hippocampal volumes remained significantly associated with remission.

Further studies with larger sample are needed to determine if left-right hippocampal volume differences do exist in depression, and basic neuroscience studies will need to elucidate the role of the hippocampus in geriatric depression.