Neural response to emotional stimuli associated with successful antidepressant treatment and behavioral activation

BackgroundMajor Depressive Disorder (MDD) is a leading cause of disability globally. Currently available treatments have limited efficacy and combination strategies are frequently used. Several lines of research have demonstrated that MDD patients experience impairments in various components of affective processing, including regulation of affective states.AimTo identify baseline and 1-week neuroimaging predictors of response to a 6-week trial of fluoxetine/olanzapine combination treatment during an affective processing task.MethodsTwenty-one MDD patients and 18 healthy controls were enrolled in the study. MDD patients were treated for 6 weeks with fluoxetine (40-60 mg/day) and olanzapine (5-12.5 mg/day). All participants viewed images from the International Affective Picture Rating System during a functional magnetic resonance (fMRI) scan at baseline and 1 week.ResultsThere was a 57% response rate (defined as a 50% decrease in Hamilton Rating Scale for Depression-17 item) at 6 weeks. At baseline, responders had increased premotor activity while viewing negative images compared to non-responders and healthy controls. Higher baseline premotor activity was also predictive of greater percent change on the HAMD-17 and improvement in negative disposition and behavioral drive. Non-responders exhibited increased insular activity at baseline compared to responders. Higher activity in the posterior cingulate cortex was also predictive of greater percent change on the HAMD-17. Change from baseline to 1 week did not produce any significant predictive findings.ConclusionsTreatment with fluoxetine/olanzapine demonstrated similar biomarkers of response to monotherapeutic strategies. In particular, posterior cingulate cortex, anterior insula, and premotor cortex may show predictive differences in their response to affective images prior to treatment. Further research needs to be conducted to determine the utility of early changes in emotion circuitry in predicting antidepressant response.