The effects of affective expectations on affective experience and dimensions of anhedonia in inpatients with major depressive disorder: a randomized clinical trial

Anhedonia is a key symptom of major depressive disorder (MDD). People with anhedonia may lose interest in activities they once enjoyed, though they can still experience some pleasure while engaging in them. This indicates a deficit in expecting pleasure rather than in the experience itself. However, the impact of affective expectations on anhedonia in patients with MDD has not yet been studied. The current study aimed to explore how affective expectations influence both the emotional experiences and the dimensions of anhedonia in patients with MDD using both objective and subjective measures. 33 inpatients with MDD were selected and randomized to the high and low-expectations groups in which subjects were induced with positive and neutral emotions, respectively, prior to watching a pleasurable video clip. All participants completed the questionnaires of Positive Valence Systems Scale-21, Affective Forecasting, Affective Experience, and Future Interest, as well as the Probabilistic Reward Task as the pre-and post-test measures. Trial registration: This study is registered by the Iranian Registry of Clinical Trials (IRCT) at 2023-07-19 (trial ID: 70082) see [IRCT20230513058161N1]. induction of positive expectations significantly raised the levels of predicted and experienced pleasure as well as future interest in participating in similar activities. In addition, the induction of positive expectation led to a significant improvement in various dimensions of anhedonia, including probabilistic and reinforcement learning and effort valuation. Inducing positive expectations in modifying affective experiences and anhedonia-related features can be considered as a promising therapeutic approach in anhedonia treatment.