Positive Valence System Dysregulation in Psychosis

Motivational and hedonic impairments cut across diagnostic categories, are core aspects of psychopathology, and may be crucial for understanding pathways to development and maintenance of psychopathology. Given the pervasive nature of motivational and hedonic deficits across psychopathology forms, the Research Domain Criteria initiative includes a “positive valence” systems domain that outlines constructs critical for understanding motivational and hedonic impairments in psychopathology. These constructs include initial responsiveness to reward, reward anticipation or expectancy, incentive or reinforcement learning, effort valuation, and action selection. The chapter reviews behavioral and neuroimaging studies providing evidence for construct impairments in in individuals with psychosis versus individuals with depressive pathology. Evidence suggests there are meaningful differences in reward-related and hedonic deficits associated with psychosis versus depression. These differences have implications for understanding the differential etiology of these forms of psychopathology and the ways treatment development may need to proceed for each domain. The literature suggests that individuals with depressive pathology experience impairments of in-the-moment hedonics or “liking,” particularly among those who experience anhedonia. Given that hedonic experience is the basis in many ways for all other aspects of motivational function, such deficits may propagate forward and contribute to impairments in other constructs dependent on hedonic responses. In contrast, individuals with psychosis have relatively intact in-the-moment hedonic processing, instead experiencing impairments in process aspects that translate reward to action selection. More specifically, individuals with schizophrenia exhibit altered reward prediction and associated striatal and prefrontal activation, impaired reward learning, and impaired reward-modulated action selection.