Effects of an antidepressant on neural correlates of emotional processing in patients with major depression

Abstract

We measured brain activation in patients with major depressive disorder when exposed to emotional pictures before and after antidepressant treatment. The participants included 18 first-episode unmedicated patients with current major depressive disorder and 18 age- and gender-matched control subjects. All subjects performed an emotional task during functional magnetic resonance imaging scanning at baseline and after 8 weeks of fluoxetine treatment. Unmedicated depressed patients showed lower accuracy rates (0.53±0.26) than did subjects in the control group (0.71±0.18) while viewing positive pictures. During exposure to positive stimuli, decreased activations were seen in the right insula (BA13) and left anterior cingulate cortex (BA32) in patients after antidepressant treatment. After antidepressant treatment, patients exhibited greater activation in the right middle frontal gyrus (BA8,9) in response to negative stimuli. Our results suggest that the prefrontal cortex, anterior cingulate cortex and insula may play key roles as biological markers for treatment response and as predictors of therapeutic success.