Major depressive disorder (MDD) can be triggered by stress experiences. Studies have shown that stress may change the reward processing (Kumar et al., 2015). What are the effects of stress exposure on the brain, such as those associated with reward processing?
In a recent study of 12 patients with MDD, the influences of acute and chronic life stress were examined. The study showed elevated activation of medial prefrontal cortex (mPFC) to reward feedback in the acute stress conditions among those with higher perceived stressor severity (Kumar et al., 2015).
In addition, those with depression had stronger associations between perceived stressor severity levels and reward-related mPFC activation in the acute stress conditions (Kumar et al., 2015). MDD patients also had lower levels of mPFC gray matter but still had robust functions in those areas.
The study concluded that MDD patients might need more mPFC activation for reward processing under stressful conditions (Kumar et al., 2015). Because the study was done in a relatively small group, more studies with larger groups are necessary to confirm the correlations among stress, depression, and brain functions including the reward-related mPFC activation.
Kumar P, Slavich GM, Berghorst LH, Treadway MT, Brooks NH, Dutra SJ, Greve DN, O’Donovan A, Bleil ME, Maninger N, Pizzagalli DA. Perceived life stress exposure modulates reward-related medial prefrontal cortex responses to acute stress in depression. J Affect Disord. 2015 Jul 15;180:104-11. doi: 10.1016/j.jad.2015.03.035.