Unraveling reward processing in schizophrenia and bipolar disorder: a multilevel examination of the positive valence system.

BACKGROUND

The positive valence systems (PVS) domain, a key focus of the Research Domains Criteria framework, divides reward-related processes into three constructs: reward responsiveness, reward learning, and reward valuation. Difficulties with several of these reward constructs have been reported in people with mood-psychosis spectrum disorders. This study aims to examine how performance on tasks corresponding to these three constructs covaries, and how performance relates to mood and psychotic symptoms in adults with mood-psychosis spectrum disorders, those at familial risk, and controls.

METHODS

Data from two studies (N = 278 and N = 332) were analyzed, which both included people with a psychotic disorder or bipolar disorder (patients), their first-degree relatives (FDRs), and controls. PVS constructs were measured using the Multi-Armed Bandit Task, Effort-Expenditure for Rewards Task, and Monetary Incentive Delay Task. Depression, mania, and psychosis symptoms were measured with self-report and interview instruments. Confirmatory factor analysis was used to examine covariation, and path analysis to test associations with symptoms.

RESULTS

The three reward constructs showed weak (nonsignificant) covariance in all groups. There were a few impairments in reward-related performance in patients or FDRs, none that survived multiple-comparison correction. There were no associations between symptoms and performance on the PVS constructs after multiple comparisons correction.

CONCLUSIONS

The findings showed no evidence that performance on any of the three PVS constructs could constitute an endophenotype of mood-psychosis spectrum disorders. We recommend future research examining the contribution of specific cognitive skills to reward-related behavior, and to sources of heterogeneity in reward functioning within the patient group.