Neural responses to monetary incentives in major depression

Background: Reduced responsiveness to positive incentives is a central feature of Major Depressive Disorder (MDD). In the present study, we compared neural correlates of monetary incentive processing in unmedicated depressed participants and never-depressed control subjects. Methods: Fourteen currently depressed and 12 never-depressed participants underwent functional magnetic resonance imaging while participating in a monetary incentive delay task. During the task, participants were cued to anticipate and respond to a rapidly presented target to gain or avoid losing varying amounts of money. Results: Depressed and never-depressed participants did not differ in nucleus accumbens (NAcc) activation or in affective or behavioral responses during gain anticipation. Depressed participants did, however, exhibit increasing anterior cingulate activation during anticipation of increasing gains, whereas never-depressed participants showed increasing anterior cingulate activation during anticipation of increasing loss. Depressed participants also showed reduced discrimination of gain versus nongain outcomes. Conclusions: The present findings indicate that although unmedicated depressed individuals have the capacity to experience positive arousal and recruit NAcc activation during gain anticipation, they also exhibit increased anterior cingulate cortex activation, suggestive of increased conflict during anticipation of gains, in addition to showing reduced discrimination of gain versus nongain outcomes.