Assessment of Anhedonia in Adults With and Without Mental Illness

Martin Trøstheim,Elisabeth Paul,Ingelin Hansen,Remy Meir,Marie Eikemo,Eric L Garland,Sara Liane Kroll,Siri Leknes

doi:10.1001/jamanetworkopen.2020.13233

Abstract

ImportanceAnhedonia, 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.ObjectiveTo generate and compare reference values for anhedonia levels in adults with and without mental illness.Data SourcesWeb 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 SelectionStudies 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 SynthesisRandom-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 MeasuresSelf-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.ResultsIn 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 RelevanceThe 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.

Highlights

Mental disorders are a major cause of disability, affecting 16% to 19% of the world’s population or approximately 1 billion people every year.[1,2] Traditional diagnostic systems, such as the Diagnostic and Statistical Manual of Mental Disorders and the International Statistical Classification of Diseases, categorize mental disorders according to constellations of symptoms
Quality Assessment Risk of bias owing to modifications of the Snaith-Hamilton Pleasure Scale (SHAPS) was low, as the questionnaire was largely invariant across studies
While anhedonia scores were significantly increased in current but not remitted major depressive disorder (MDD), schizophrenia, substance use disorder (SUD), Parkinson disease (PD), and chronic pain compared with healthy participants, we found evidence for substantially higher anhedonia in ongoing MDD compared with other types of illness

Summary

Introduction

Mental disorders are a major cause of disability, affecting 16% to 19% of the world’s population or approximately 1 billion people every year.[1,2] Traditional diagnostic systems, such as the Diagnostic and Statistical Manual of Mental Disorders and the International Statistical Classification of Diseases, categorize mental disorders according to constellations of symptoms. Comorbidity is common, suggesting overlap in symptoms between diagnoses. The ability to experience pleasure is essential for well-being,[4] but is often reduced in mental illness. Anhedonia is defined as a reduced capacity for pleasure[5] and has been described in major depressive disorder (MDD),[6,7] bipolar disorder,[6] schizophrenia,[6,8,9,10,11] substance use disorder (SUD),[12,13] chronic pain,[14,15] and Parkinson disease (PD).[16,17] Despite its presence across numerous psychiatric and neurologic disorders, anhedonia is rarely compared across conditions. Whether anhedonia differs in severity between diagnoses is currently unknown

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