Anhedonia and Reward Learning in Major Depression: State or Trait?

Background: Anhedonia and reward processing deficits are core features of Major Depressive Disorder (MDD). However, their persistence following remission remains unclear, hindering the differentiation between state versus trait characteristics. This study investigated clinically assessed anhedonia and reward-related learning in individuals with current MDD (MD), remitted MDD (RMD), and healthy controls (HC). Methods: We assessed 26 individuals with current MDD, 35 with RMD, and 37 HC. Anhedonia was measured using the Clinician-Administered Snaith-Hamilton Pleasure Scale (SHAPS-C-TR). Reward-related learning was evaluated using the Probabilistic Reward Task (PRT). Depressive and anxiety symptoms were also assessed. Results: The MD group exhibited significantly higher anhedonia and greater depressive and anxiety symptoms compared to both RMD and HC groups. Crucially, anhedonia scores did not differ between the RMD and HC groups. While a significant learning effect on the PRT was observed across the entire sample, there were no significant differences in task performance among the three groups, even after controlling for covariates. Conclusion: Clinically assessed anhedonia appears to be a state-dependent symptom that normalizes with remission. In contrast, reward-related learning, assessed via the PRT, was not significantly impaired in either current or remitted depression. These findings suggest a potential dissociation between the experience of clinically assessed anhedonia and reward learning deficits in MDD.