Reward Motivation Adaptation Deficits Are Specific to Co-Occurring Subclinical Depression and Anhedonia.

Reward motivation adaptation is defined as the extent to which the willingness to exert effort varies as a function of incentive salience, encompassing both motivational ('wanting') and hedonic ('liking') components. Although reduced reward motivation has been reported in subclinical depression and anhedonia, it remains unclear whether impaired adaptation is a general feature of subclinical depression or is more evident when depressive symptoms co-occur with anhedonia. We addressed this question in two behavioral studies using a task that systematically varied effort-reward ratios. Study 1 contrasted three screening-based groups: individuals with elevated social anhedonia, individuals with subclinical depression without high social anhedonia, and controls with low levels of both, and found no clear group differences in reward motivation adaptation across effort-reward conditions. Study 2 focused on female participants with subclinical depression who also showed higher levels of anhedonia, compared with non-depressed controls. In this sample, the subclinical depression group showed lower overall reward motivation and indications of reduced 'liking' adaptation. In conclusion, these findings suggest that deficits in reward motivation adaptation were not clearly observable when subclinical depression or social anhedonia were considered in isolation, but may emerge when depressive status and broader measures of anhedonia co-occur, though this pattern requires confirmation in larger and more diverse samples.