Acute stress-induced reductions in neural response to reward are related to acute stress-related increases in cortisol.

Stressors and blunted reward processing are implicated in depression. The current study simultaneously examined the impact of an acute stressor on cortisol and reward processing, measured using the reward positivity (RewP) in 66 participants. Participants completed a reward task during a stressor and a control condition, counterbalanced, and separated by 1 week, while saliva samples were collected before, immediately following, and 25 min after the reward task. Participants reported that the stressor condition was more stressful than the control condition. Cortisol levels did not differ before the reward task; however, cortisol levels were higher both immediately and 25 min after the task. The RewP was blunted during the stressor compared to the control condition, and participants with a larger stress-induced increase in cortisol had greater reductions in their RewP. The current study provides evidence that stress-induced changes in HPA-axis functioning relate to reductions in neural correlates of reward processing.