Effects of repetitive negative thinking on neural and behavioral correlates of anhedonia in depressive symptomatology

Rationale. Depressive symptomatology is characterized by anhedonia and rumination, implicated in repetitive negative thinking (RNT). Despite the increasing knowledge about the role of RNT in the development, maintenance and recurrence of the disorder, the underlying mechanisms linking anhedonic behaviors and ruminative thoughts are not yet fully understood. Methods. The present randomized, within-subjects study, included 62 individuals (n = 38 females) with different severity of depressive symptoms, who performed the Probabilistic Reward Task (PRT) under two conditions: experimentally induced RNT and an active control. Concurrent electroencephalography was recorded to derive event-related potentials associated with reward processing. Subjective responses to RNT induction were assessed using Visual Analog Scales (VASs). Results. Compared to the control condition, RNT induction significantly reduced both reward responsiveness and feedback-related positivity (FRP) amplitudes to the most frequently rewarded stimulus in the PRT. Blunted behavioral and neural responses were considerably pronounced in individuals with more severe depressive symptoms. The effects of RNT induction on reward-related processes were independent of task difficulty or perceptual cortical processing of PRT stimuli. Conclusions. These findings suggest that maladaptive cognitions such as RNT may reveal or amplify the latent reward processing deficits associated with anhedonic symptomatology. This specific vulnerability informs about the potential implications of targeting RNT in the treatment of reward processing deficits in depression.