Assessment of Anhedonia in Adults With and Without Mental Illness: A Systematic Review and Meta-analysis

Abstract

Importance: Anhedonia, a reduced capacity for pleasure, is described for many psychiatric and neurologic conditions. However, a decade after the Research Domain Criteria launch, whether anhedonia severity differs between diagnoses is still unclear. Reference values for hedonic capacity in healthy humans are also needed.

Objective: To generate and compare reference values for anhedonia levels in adults with and without mental illness.

Data sources: Web of Science, Scopus, PubMed, and Google Scholar were used to list all articles from January 1, 1995 to July 2, 2019, citing the scale development report of a widely used anhedonia questionnaire, the Snaith-Hamilton Pleasure Scale (SHAPS). Searches were conducted from April 5 to 11, 2018, and on July 2, 2019.

Study selection: Studies including healthy patients and those with a verified diagnosis, assessed at baseline or in a no-treatment condition with the complete 14-item SHAPS, were included in this preregistered meta-analysis.

Data extraction and synthesis: Random-effects models were used to calculate mean SHAPS scores and 95% CIs separately for healthy participants and patients with current major depressive disorder (MDD), past/remitted MDD, bipolar disorder, schizophrenia, substance use disorders, Parkinson disease, and chronic pain. SHAPS scores were compared between groups using meta-regression, and traditional effect size meta-analyses were conducted to estimate differences in SHAPS scores between healthy and patient samples. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines.

Main outcomes and measures: Self-reported anhedonia as measured by 2 different formats of the SHAPS (possible ranges, 0-14 and 14-56 points), with higher values on both scales indicating greater anhedonia symptoms.

Results: In the available literature (168 articles; 16 494 participants; 8058 [49%] female participants; aged 13-72 years), patients with current MDD, schizophrenia, substance use disorder, Parkinson disease, and chronic pain scored higher on the SHAPS than healthy participants. Within the patient groups, those with current MDD scored considerably higher than all other groups. Patients with remitted MDD scored within the healthy range (g = 0.1). This pattern replicated across SHAPS scoring methods and was consistent across point estimate and effect size analyses.

Conclusions and relevance: The findings of this meta-analysis indicate that the severity of anhedonia may differ across disorders associated with anhedonia. Whereas anhedonia in MDD affects multiple pleasure domains, patients with other conditions may experience decreased enjoyment of only a minority of life's many rewards. These findings have implications for psychiatric taxonomy development, where dimensional approaches are gaining attention. Moreover, the SHAPS reference values presented herein may be useful for researchers and clinicians assessing the efficacy of anhedonia treatments.

Conflict of interest statement

Conflict of Interest Disclosures: Ms Meir reported receiving grants and nonfinancial support from Fulbright Norway during the conduct of the study. Ms Paul reported receiving grants from Region Östergötland and the Swedish Research Council during the conduct of the study. Dr Leknes reported receiving grants from the European Research Council and the South-Eastern Norway Regional Health Authority during the conduct of the study. No other disclosures were reported.

Figures

Figure 1. PRISMA Flow Diagram of the Article selection Process

Figure 2. Sets of Meta-analysis of Snaith-Hamilton Pleasure Scale (SHAPS) Scores Across Groups

A, SHAPS scores from studies using 1- to 4-point scoring showing significantly higher anhedonia in all patient groups compared with healthy individuals. B, SHAPS scores from studies using the original 0- to 1-point scoring method replicates the pattern found in studies using 4-point scoring. Note that except for chronic pain, there was no overlap between studies included in A and B. C, Effect sizes based on studies reporting scores from patients and controls, according to both scoring methods. Diamonds indicate mean and 95% CI. White dots indicate individual sample means. I indicates the amount of variation between samples that is due to heterogeneity rather than chance; Q, Cochran Q test; and T, estimated between-samples SD. aP < .001. bP < .01. cP < .05.

Figure 3. Exploratory item-Level Meta-analysis

To test whether patients with a specific mental health diagnosis typically experience anhedonia for the same subset of pleasures, we conducted an exploratory meta-analysis of raw, item-level data from 376 healthy volunteers, 64 patients with major depression, and 487 chronic pain patients (for details, see eAppendix 1 in the Supplement). Item-level data for other groups were not available to us at the time of writing. Diamonds indicate mean and 95%CI. SHAPS indicates Snaith-Hamilton Pleasure Scale.