反芻思考における報酬処理障害の行動的および電気生理学的証拠：うつ病への示唆

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. Although their interaction is thought to sustain depressive states, the state-level mechanisms linking these symptoms remain poorly understood.

In this multilevel, randomized within-subjects study, 62 individuals (n = 38 females) with varying levels of depressive symptoms completed the Probabilistic Reward Task (PRT) under two conditions: experimentally induced RNT and an active control. Concurrent electroencephalography was employed to assess electroencephalographic markers of reward functioning.

RNT significantly attenuated both reward response bias and feedback-related positivity (FRP) amplitudes, with the most pronounced effects in individuals with more severe depressive symptoms. These effects were not attributable to differences in task difficulty or perceptual cortical processing of PRT stimuli, supporting the specificity of RNT's impact on reward-related processes.

RNT may transiently disrupt behavioral and neural indicators of reward functioning. These findings suggest that cognitive states such as RNT can exacerbate or reveal the latent reward-processing deficits typically observed in individuals with anhedonia. This state-dependent sensitivity highlights the potential utility of targeting RNT to restore reward processing in depression.