Greater neural delay discounting on reward evaluation in anhedonia

Recent years have witnessed a surge of interest in dissecting the anticipatory and the consummatory aspects of anhedonia in terms of temporal dynamics. However, few research has directly examined reward valuation as a function of time in anhedonia.

Using a delay discounting task, this event-related potential study examined the neural representation of rewards available immediately or in six months in a high-anhedonia group (N = 40) and a low-anhedonia group (N = 40) recruited from a nonclinical sample.

We found that anhedonia was associated with greater neural delay discounting during reward evaluation. This was evidenced by a blunted effect of reward magnitude on the reward positivity (RewP) in the high-anhedonia compared to the low-anhedonia group when the rewards would be delivered six months later. Representation similarity analysis revealed that the aberration in processing delayed rewards is further corroborated by enhanced neural coding of reward time during the RewP period in the high-anhedonia versus low-anhedonia group.

These findings provide empirical evidence to show that anhedonia is driven by a blunted neural representation of future rewards instead of immediate rewards, suggesting an inability to form mental representations of future positive experiences in anhedonia.