Anhedonia in eating disorders: A meta-analysis and systematic review.

OBJECTIVE Anhedonia, or loss of pleasure, is related to deficits in reward processing across a variety of psychiatric disorders. In light of research suggesting abnormal reward processing in eating disorders (EDs), the study of anhedonia in EDs may yield important insights into the role of reward in eating pathology. This meta-analysis and review aimed to provide both a quantitative and qualitative synthesis of the existing literature on this topic. METHOD We conducted this research (or these meta-analyses) according to PRISMA guidelines. We searched four databases for both peer-reviewed and unpublished literature, and included studies only if a self-report or clinical interview measure of anhedonia was administered to a sample with an ED diagnosis. RESULTS We included 21 studies in the systematic review, and 10 studies in two meta-analyses that compared anhedonia between ED and control samples (n = 9 studies) and within different ED diagnoses (n = 5 studies). Meta-analyses revealed that anhedonia was significantly higher in ED groups compared to healthy controls, but there was no significant difference in anhedonia between ED diagnostic groups. A qualitative review of the literature also suggested that anhedonia may be correlated with increased ED symptom severity. DISCUSSION Findings indicated that anhedonia is elevated in EDs and may be a relevant treatment target. Future research should examine how self-reported anhedonia may correlate with components of reward processing in EDs in order to improve theoretical models as well as targeted interventions.