Altered Functional Magnetic Resonance Imaging Markers of Affective Processing During Treatment of Late-Life Depression

Abstract

This study investigated neural substrate changes in affective processing among late-life depression (LLD) patients undergoing antidepressant treatment and determined if these changes correlated with remission status. Thirty-three LLD patients were enrolled in a 12-week venlafaxine treatment course. During treatment functional magnetic resonance imaging (fMRI) scans, paired with an affective task that assessed emotional reactivity and regulation, were performed on days 1, 2, 3, and 7 and at week 12. Following treatment patients were classified as remitters or non-remitters. A voxel-wise two-way repeated-measures ANOVA was performed to assess the fMRI data at a significance level of α = 0.05, corrected. The emotional reactivity contrast demonstrated a significant interaction between remission status and scan time in the right middle temporal gyrus (MTG) (F = 24.1, df = 1,112, k = 102). Further analysis showed increased emotional reactivity-induced activity among non-remitters, and decreased activity among remitters, which significantly differed from baseline at day 7 (95% CI: 0.027, 0.540; Cohen's d = -1.35) and week 12 (95% CI: -0.171, -0.052; Cohen's d = 0.68), respectively. No significant interaction was observed with the emotional regulation contrast, but multiple regions had significant main effects of scan time, including the cuneus, occipital lobe, insula, lingual gyrus, posterior cingulate cortex, and MTG. During treatment of LLD patients, affective processing-induced activity in the right MTG shows changes based on remission status. This alteration becomes evident early during the course of treatment, suggesting that antidepressant pharmacotherapy may acutely affect the neural basis of emotional reactivity in a differential manner that is relevant to illness remission.