Abstract/Summary

Background: Anhedonia and depression symptoms have been linked to potential deficits in reward learning. However, how anhedonia impacts the ability to adjust and learn about the effort required to obtain rewards remains unclear. Methods: We examined young people (N = 155, 16 to 25 years) with a range of depression and anhedonia symptoms using a probabilistic instrumental reward and effort learning task. Participants were asked to learn which option to choose to maximize reward or minimise effort for reward. We compared the exerted effort (button pressing speed) for high (puppy images) vs low (dog images) rewards and collected subjective reports of “liking”, “wanting” and “willingness to exert effort”. Computational models were fit to the learning data and estimated parameter values were correlated with depression and anhedonia symptoms. Results: As depression symptoms and consummatory anhedonia increased, reward liking decreased, and as anticipatory anhedonia increased, liking, wanting and willingness to exert effort for reward decreased. Participants exerted more effort for high rewards than for low rewards, but anticipatory anhedonia diminished this difference. Higher consummatory anhedonia was associated with poorer reward and effort learning, and with increased temperature parameter values for both learning types, indicating a higher tendency to make exploratory choices. Higher depression symptoms were associated with lower reward learning accuracy. Conclusion: We provide novel evidence that anhedonia is associated with difficulties in modulating effort as a function of reward value. Regarding the computational mechanisms underpinning learning in anhedonia, we demonstrate that anhedonia is associated with the underexploitation of low effort and high reward options. We suggest that addressing the impairments in exploration/exploitation behaviours in anhedonic young people could be a novel target for intervention.