Characterizing anhedonia: A systematic review of neuroimaging across the subtypes of reward processing deficits in depression

Abstract

Anhedonia is a key symptom of major depressive disorder (MDD) and comprises behavioural deficits in three reward processing subtypes: reward liking, reward wanting, and reward learning. However, neuroimaging findings regarding the neural abnormalities underpinning these deficits are complex. We have conducted a systematic review to update, reframe and summarize neuroimaging findings across the three subtypes of anhedonia in MDD. Using PubMed, The Cochrane Library, PsycINFO, and Web of Science databases, we identified 59 fMRI studies comparing participants with current or remitted MDD with controls, using reward processing tasks. For reward liking and wanting, striatal hypoactivation was observed, alongside hypoactivation and hyperactivation across frontal regions. For reward learning, blunted frontostriatal sensitivity to positive feedback was observed. These findings highlight the importance of studying anhedonia not only as a clinical manifestation but also as a neurobiological mechanism underlying depressive disorder and other broader psychiatric conditions.

Keywords: Anhedonia; Depression; Neuroimaging; Reward processing; fMRI.

Fig. 1

PRISMA flow diagram showing flow of information through the systematic review process, including records identified, screened, included, and excluded

Fig. 2

Summary of the total number of studies included and the number of studies identified for each subtype of anhedonia. Six papers were included in both reward liking and reward wanting, and one paper was included in all three subtypes