Behavioral and electrophysiological evidence of reward processing deficits in repetitive negative thinking: implications for depression

Anhedonia and rumination, a form of repetitive negative thinking (RNT), are key features of depression associated with poor treatment outcomes, chronic disease progression, and an increased risk of suicidality. Despite their hypothesized interaction in sustaining depression, the mechanisms connecting these symptoms remain unclear. This within-subjects study examined reward processing during the Probabilistic Reward Task (PRT) under experimentally induced RNT and an active control condition in 62 individuals (n = 38 females) with varying levels of depressive symptoms. Results indicated a significantly reduced reward response bias and feedback-related positivity (FRP) during the RNT condition, with effects most pronounced in individuals with severe depressive symptoms. Additionally, FRP amplitude was correlated with both reward response bias and subjective response to the induction. These findings suggest that RNT worsens both behavioral and electrophysiological markers of reward processing deficits in individuals with high depressive symptoms, offering insight into the mechanisms linking rumination and anhedonia in depression.