Addicted to compulsion: assessing three core dimensions of addiction across obsessive-compulsive disorder and gambling disorder

Breaking New Ground With Endoxifen: Augmentation Strategies in OCD Management-A Case Series

Obsessive-compulsive (OC) disorder (OCD) is a common and potentially disabling illness with a waxing and waning course. OCD significantly disrupts the quality of life. Selective serotonin reuptake inhibitors (SSRIs) are first-line pharmacological treatments for OCD and benefit up to half of the patients. Augmentation with low-dose antipsychotics is an evidence-based second-line strategy. Psychotherapy, including cognitive behavior therapy (CBT), is used both as first and second-line treatment. A significant portion of patients, however, do not respond to conventional treatments. We present a case series on the use of Endoxifen as an augmenting agent in patients with OCD and multiple psychiatric comorbidities who did not respond well to conventional pharmacotherapy.

Manipulating levels of uncertainty in a decision-making task for obsessive compulsive disorder

OBJECTIVE

We investigated whether manipulating levels of uncertainty would influence performance in a decision-making task in people with obsessive-compulsive disorder.

METHODS

This case-control study compares Beads Task (measuring reflection/decisional impulsivity) performance and trait impulsivity (Short Urgency-Premeditation-Perseverance-Sensation Seeking-Positive Urgency [UPPS-P] Impulsive Behavior Scale) in patients with obsessive-compulsive disorder (n = 65) and non-clinical controls (n = 45). Differences between groups were assessed with the Mann Whitney U test.

RESULTS

The obsessive-compulsive disorder group had significantly fewer draws to decision (U = 1,845, p = 0.019) and less subjective decision-certainty (U = 1,518, p = 0.00) in the low uncertainty (85:15) condition, and higher negative urgency scores (U = 2,163, p ≤ 0.001) and lower sensation-seeking scores (U = 907.5, p = 0.001) in UPPS-P. However, differences in Beads Task performance did not survive correction for multiple comparisons.

CONCLUSION

Patients with obsessive-compulsive disorder engage in more impulsive decision-making in the lower uncertainty condition than healthy controls, despite low subjective certainty of the decision. They also had higher scores for the trait impulsivity factor of negative urgency. Future studies should explore the contribution of trait impulsivity, as well as symptom severity, anxiety, and decision-certainty, to impulsivity in obsessive-compulsive disorder.

Obsessive-compulsive disorder, major depressive disorder, and addiction: the vicious relationship

Obsessive-Compulsive Disorder (OCD) and Major Depressive Disorder (MDD) are prevalent psychiatric conditions, each affecting a substantial portion of the global population. When these conditions coexist with a Substance Use Disorder (SUD), the complexity of the clinical presentation is heightened. Herein, we describe two cases of individuals who have comorbid OCD and/or MDD and substance use disorder that highlight the importance of addressing the coexisting psychiatric illness when treating the SUD. These cases highlight the importance of tailored, multidisciplinary care, offering a potential therapeutic strategy based on medications for comprehensive recovery in individuals facing complex comorbid disorders. An integrated treatment approach, encompassing both psychiatric and substance treatment perspectives, is imperative.

The relationship between cognitive phenotypes of compulsivity and impulsivity and clinical variables in obsessive-compulsive disorder: A systematic review and Meta-analysis

BACKGROUND

This systematic review and meta-analysis explored the relationship between cognitive phenotypes of compulsivity and impulsivity and clinical variables in obsessive-compulsive disorder (OCD).

METHODS

We searched Pubmed, Scopus, Cochrane Library and PsychINFO databases until February 2023 for studies comparing patients with OCD and healthy controls on cognitive tests of compulsivity and impulsivity. The study followed PRISMA guidelines and was pre-registered on PROSPERO (CRD42021299017).

RESULTS

Meta-analyses of 112 studies involving 8313 participants (4289 patients with OCD and 4024 healthy controls) identified significant impairments in compulsivity (g = -0.58, [95%CI -0.68, -0.47]; k = 76) and impulsivity (g = -0.48, [95%CI -0.57, -0.38]; k = 63); no significant difference between impairments. Medication use and comorbid psychiatric disorders were not significantly related to impairments. No associations were revealed with OCD severity, depression/anxiety, or illness duration.

CONCLUSION

Cognitive phenotypes of compulsivity and impulsivity in patients with OCD appear to be orthogonal to clinical variables, including severity of OCD symptomatology. Their clinical impact is poorly understood and may require different clinical assessment tools and interventions.

Disentangling associations between impulsivity, compulsivity, and performance monitoring

Disorders marked by high levels of impulsivity and compulsivity have been linked to changes in performance monitoring, specifically the error-related negativity (ERN). We investigated the relationship between performance monitoring and individual differences in impulsivity and compulsivity. A total of 142 participants were recruited into four groups, each with different combinations of impulsivity and compulsivity, and they performed a flanker task to assess error-related brain activity. We defined error-related brain activity as ERN amplitude and theta power. Single-trial regression was employed to analyze the amplitude differences between incorrect and correct trials within the ERN time window. The findings revealed that impulsivity, compulsivity, and different measures of response processing exhibited distinct interactions, which were influenced by the configuration of impulsivity and compulsivity, but also depended on the measure of response processing. Specifically, high compulsivity predicted larger ERN amplitudes in individuals with low impulsivity, whereas high impulsivity had no significant effect on ERN amplitude in individuals with low compulsivity. Furthermore, when both impulsivity and compulsivity were high, no significant increase in ERN amplitude was observed; instead, there was a reduced difference between incorrect and correct trials. No significant differences were found for theta power. While the association between error-related brain activity and transdiagnostic markers or psychopathology may be smaller than generally assumed, considering the interaction between different transdiagnostic markers and their facets can enhance our understanding of the complex associations that arise during the investigation of neural correlates of performance monitoring, specifically the ERN.

Individualized, connectome-based, non-invasive stimulation of OCD deep-brain targets: A proof-of-concept

Treatment-resistant obsessive-compulsive disorder (OCD) generally improves with deep-brain stimulation (DBS), thought to modulate neural activity at both the implantation site and in connected brain regions. However, its invasive nature, side-effects, and lack of customization, make non-invasive treatments preferable. Harnessing the established remote effects of cortical transcranial magnetic stimulation (TMS), connectivity-based approaches have emerged for depression that aim at influencing distant regions connected to the stimulation site. We here investigated whether effective OCD DBS targets (here subthalamic nucleus [STN] and nucleus accumbens [NAc]) could be modulated non-invasively with TMS. In a proof-of-concept study with nine healthy individuals, we used 7T magnetic resonance imaging (MRI) and probabilistic tractography to reconstruct the fiber tracts traversing manually segmented STN/NAc. Two TMS targets were individually selected based on the strength of their structural connectivity to either the STN, or both the STN and NAc. In a sham-controlled, within-subject cross-over design, TMS was administered over the personalized targets, located around the precentral and middle frontal gyrus. Resting-state functional 3T MRI was acquired before, and at 5 and 25 min after stimulation to investigate TMS-induced changes in the functional connectivity of the STN and NAc with other regions of the brain. Static and dynamic seed-to-voxel correlation analyses were conducted. TMS over both targets was able to modulate the functional connectivity of the STN and NAc, engaging both overlapping and distinct regions, and unfolding following different temporal dynamics. Given the relevance of the engaged connected regions to OCD pathology, we argue that a personalized, connectivity-based procedure is worth investigating as potential treatment for refractory OCD.

Cannabis use and related clinical variables in patients with obsessive-compulsive disorder

OBJECTIVE

Limited studies have investigated cannabis use in patients with obsessive-compulsive disorder (OCD), despite its widespread use by patients with psychiatric illnesses. The aim of this study was to assess the frequency, correlates, and clinical impact of cannabis use in an Italian sample of patients with OCD.

METHODS

Seventy consecutive outpatients with OCD were recruited from a tertiary specialized clinic. To assess cannabis-related variables, patients completed a questionnaire developed for the purpose of this study, investigating cannabis use-related habits and the influence of cannabis use on OCD symptoms and treatments. A set of clinician and self-reported questionnaires was administered to measure disease severity. The sample was then divided into three subgroups according to the pattern of cannabis use: "current users" (CUs), "past-users" (PUs), and "non-users" (NUs).

RESULTS

Approximately 42.8% of patients reported lifetime cannabis use and 14.3% reported current use. Approximately 10% of cannabis users reported an improvement in OCD symptoms secondary to cannabis use, while 23.3% reported an exacerbation of anxiety symptoms. CUs showed specific unfavorable clinical variables compared to PUs and NUs: a significant higher rate of lifetime use of tobacco, alcohol, and other substances, and a higher rate of pre-OCD onset comorbidities. Conversely, the three subgroups showed a similar severity of illness.

CONCLUSION

A considerable subgroup of patients with OCD showed a predisposition towards cannabis use and was associated with some specific clinical characteristics, suggesting the need for targeted consideration and interventions in this population.

Behavioral domains in compulsive rats: implications for understanding compulsive spectrum disorders

Introduction

Compulsive behavior has been proposed as a transdiagnostic trait observed in different neuropsychiatric disorders, such as obsessive-compulsive disorder, autism, and schizophrenia. Research Domain Criteria (RDoC) strategy could help to disentangle the neuropsychological basis of compulsivity for developing new therapeutic and preventive approaches. In preclinical research, the selection of high-drinker (HD) vs. low-drinker (LD) animals by schedule-induced polydipsia (SIP) is considered a putative model of compulsivity, which includes a well-differentiated behavioral pattern.

Methods

The purpose of this research was to assess the cognitive control and the negative valence system domains in a phenotype of compulsive HD rats. After the selection of animals as HD or LD, we assessed behavioral inflexibility by probabilistic spatial reversal learning (PSRL), motor and cognitive impulsivity by variable delay-to-signal (VDS), and risky decision-making by rodent gambling task (rGT).

Results

HD rats performed fewer reversals and showed less probability of pressing the same lever that was previously reinforced on PSRL, more premature responses after the exposure to longer delays on VDS, and more disadvantageous risky choices on rGT. Moreover, HD animals performed more perseverative responses under the punishment period on rGT.

Discussion

These results highlight that HD compulsive phenotype exhibits behavioral inflexibility, insensitivity to positive feedback, waiting impulsivity, risky decision-making, and frustrative non-reward responsiveness. Moreover, these findings demonstrate the importance of mapping different behavioral domains to prevent, treat, and diagnose compulsive spectrum disorders correctly.

Impulsivity in Depression: Its Relation to Suicidality

OBJECTIVE

Impulsivity is an important risk for suicidality, which is common in patients with major depressive disorder (MDD). The goal of this study was to examine multiple facets of impulsivity in depressed patients compared with healthy controls and to assess their relationship to suicidality.

METHOD

Outpatients diagnosed with MDD using the Structured Clinical Interview for DSM-IV were recruited. Two groups were constituted as "MDD in remission" (n=32) and "MDD" (n=71). The "healthy control" group (n=30) consisted of individuals who had never been diagnosed with any psychiatric disorder. Impulsivity was assessed with the Barratt Impulsivity Scale (BIS), a self-rating measure, and with the following behavioral tasks: Go/No-go Task, Iowa Gambling Task, and Balloon Analogue Risk Task. The scores of the 3 groups (n=133) were compared to evaluate the effect of MDD. The scores were also analyzed and compared in the patients in the 2 MDD groups (n=103) with respect to their current and lifetime suicidality.

RESULTS

There was no difference in the 3 groups in task scores, but nonplanning BIS was correlated with the severity of depressive symptoms. Patients with suicidal ideation (SI) had higher BIS total and attention impulsivity scores and more commission errors on the Go/No-go Task, reflecting failure in response inhibition, compared with the patients without SI.

CONCLUSIONS

Failure to show differences in impulsivity-related tasks suggests that there might be no relationship between the state of depression and impulsivity. However, these findings confirm that there is an association between SI and response inhibition and the attention facet of impulsivity in depression.

The anticipatory and consummatory interpersonal pleasure scale: Applicability to Chinese OCD patients

As a transdiagnostic symptom, social anhedonia has gained increasing attention. Evidence suggests that obsessive-compulsive disorder (OCD) patients demonstrate social anhedonia. This study examined the psychometric properties of the Anticipatory and Consummatory Interpersonal Pleasure Scale (ACIPS) in an undergraduate sample and Chinese OCD patients. Furthermore, we explored the relationship between clinical symptoms and ACIPS scores. This study involved 3,306 undergraduate students and 293 patients with OCD. Internal consistency and convergent validity of ACIPS were examined. Confirmatory factor analysis (CFA) was applied to determine the best-fitting of potential factor models, and multi-group CFA was used to examine measurement invariance across genders and samples. Additionally, hierarchical linear regression was conducted in order to investigate the relationship between clinical symptoms and ACIPS scores in patients suffering from OCD. ACIPS showed acceptable internal consistency in undergraduate and OCD samples (Cronbach's α = 0.93 and 0.89, respectively). In both samples, the four-factor structure had the best fit index. Scalar invariance was established across undergraduate and OCD samples, while residual invariance was established across genders. In both samples, the ACIPS was significantly correlated with the Revised Social Anhedonia Scale and Beck Depression Inventory. Depression and the severity of obsessive thoughts significantly and negatively correlated with the ACIPS score in OCD patients (p < 0.05). In conclusion, ACIPS is a reliable, effective, simple, and convenient tool for the assessment of social anhedonia. Depression and obsessive thoughts contribute to social anhedonia in OCD patients.

Subjective assessments of research domain criteria constructs in addiction and compulsive disorders: a scoping review protocol

INTRODUCTION

Obsessive-compulsive and related disorders (OCRDs) and disorders due to addictive behaviours (DABs) are prevalent conditions that share behavioural and neurobiological characteristics. The Research Domain Criteria lists a series of constructs whose dysfunctions may be present in both groups of disorders. The present study will describe the research protocol of a scoping review of the literature on self-report scales and questionnaires that tap dysfunctional constructs that underlie OCRDs and DABs.

METHODS AND ANALYSIS

This protocol outlines a scoping review on self-report tools and questionnaires that assess OCRDs and DABs-related constructs. The scoping review will select sources in MEDLINE, EMBASE, PsychINFO and Web of Science databases. Inclusion and exclusion criteria will be designed according to the Population, Concept, Context, Types of source framework. Two reviewers will screen independently titles, abstracts and full texts to determine the eligibility of articles. A methodological framework including six stages steps ((1) identifying a research question; (2) identifying relevant studies; (3) study selection; (4) charting the data; (5) collating, summarising and reporting the result) will be used, and the findings will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews checklist. Information extracted will be collated, and quantitative results will be presented using descriptive statistics such as percentages, tables, charts and flow diagrams as appropriate.

ETHICS AND DISSEMINATION

Ethical approval for conducting this scoping review is not required, as this study will involve secondary analysis of existing literature. The researchers will disseminate the study results via conference presentations and publication in a peer-reviewed journal.

SCOPING REVIEW PROTOCOL REGISTRATION

DOI 10.17605/OSF.IO/UJ7G5.

Inverse Association Between Resting-State Putamen Activity and Iowa Gambling Task Performance in Patients With Obsessive-Compulsive Disorder and Control Subjects

BACKGROUND

Symptoms of obsessive-compulsive disorder (OCD) have been conceptualized as manifestations of decision-making deficits. Patients with OCD exhibit impairment during the decision-making process, as assessed by the Iowa Gambling Task (IGT). This impairment is independent of clinical severity and disease progression. However, the association between the decision-making deficit and resting-state brain activity of patients with OCD has not been examined.

METHODS

Fifty unmedicated patients with OCD and 55 matched control subjects completed IGT. Resting-state brain activity was examined using the fractional amplitude of low-frequency fluctuations (fALFFs). fALFF analysis focused on the slow-4 and 5 bands. Group comparisons were performed to determine the association between IGT performance and fALFFs.

RESULTS

There was a significant group difference in the association between the IGT total net score and slow-4 fALFFs in the left putamen (voxel height threshold of p < 0.001; cluster size threshold of p < 0.05; family wise error-corrected). Higher putamen slow-4 fALFFs were correlated with lower IGT scores for OCD patients (r = -0.485; p < 0.0005) and higher IGT scores for control subjects (r = 0.402; p < 0.005). There was no group difference in the association between the IGT total net score and slow-5 fALFFs.

CONCLUSIONS

These findings in unmedicated patients demonstrate the importance of resting-state putamen activity for decision-making deficit associated with OCD, as measured by IGT. The inverse correlation may be explained by the hypersensitive response of the putamen in patients with OCD.

Toward a neurocircuit-based taxonomy to guide treatment of obsessive-compulsive disorder

An important challenge in mental health research is to translate findings from cognitive neuroscience and neuroimaging research into effective treatments that target the neurobiological alterations involved in psychiatric symptoms. To address this challenge, in this review we propose a heuristic neurocircuit-based taxonomy to guide the treatment of obsessive-compulsive disorder (OCD). We do this by integrating information from several sources. First, we provide case vignettes in which patients with OCD describe their symptoms and discuss different clinical profiles in the phenotypic expression of the condition. Second, we link variations in these clinical profiles to underlying neurocircuit dysfunctions, drawing on findings from neuropsychological and neuroimaging studies in OCD. Third, we consider behavioral, pharmacological, and neuromodulatory treatments that could target those specific neurocircuit dysfunctions. Finally, we suggest methods of testing this neurocircuit-based taxonomy as well as important limitations to this approach that should be considered in future research.

Frontoparietal hyperconnectivity during cognitive regulation in obsessive-compulsive disorder followed by reward valuation inflexibility

Obsessive-compulsive disorder (OCD) is characterized by cognitive deficits and altered reward processing systems. An imbalance between cognitive and reward pathways may explain the lack of control over obsessions followed by rewarding compulsive behaviors. While the processes of emotional cognitive regulation are widely studied in OCD, the mechanisms of cognitive regulation of reward are poorly described. Our goal was to investigate the OCD impact on cognitive regulation of reward at behavioral and neural functioning levels. OCD and control participants performed a functional magnetic resonance imaging task where they cognitively modulated their craving for food pictures under three cognitive regulation conditions: indulge/increase craving, distance/decrease craving, and natural/no regulation of craving. After regulation, the participants gave each picture a monetary value. We found that OCD patients had fixed food valuation scores while the control group modulated these values accordingly to the regulation conditions. Moreover, we observed frontoparietal hyperconnectivity during cognitive regulation. Our results suggest that OCD is characterized by deficits in cognitive regulation of internal states associated with inflexible behavior during reward processing. These findings bring new insights into the nature of compulsive behaviors in OCD.

Online Gambling in Iranian Social Media Users: Prevalence, Related Variables and Psychiatric Correlations

The exponential increase in Internet use has been associated with dangers and harms. Recently, the prevalence of online gambling is increasing in various countries. Online gambling can be a prelude to gambling disorder. No study has been conducted in this field in Iran yet. The aim of this study was to investigate the prevalence of online gambling (without disorder and pathological), and its relationship with demographic variables and psychiatric symptoms. 3252 people participated in this study online. Research tools included gambling disorder screening questionnaire-Persian (GDSQ-P), brief symptom inventory (BSI), Young's addiction questionnaire, and Demographic questionnaire. The prevalence of online gambling was 8.9%. 26.6% of online gamblers experience moderate to severe degrees of pathological gambling. 74.7% of online gamblers were male. Online gamblers have a lower mean age than non-online gamblers (p < 0.001). Online gamblers were equally from all economic classes. The most common methods of gambling were CRASH game and sports betting. Online gamblers had no significant difference in the rate of face-to-face (physical) gambling history, compared to non-online gamblers (6.9% vs 5.6%), (p > 0.05). In BSI-assessed psychiatric symptoms, online gamblers showed higher scores on anxiety and obsession, and lower scores on paranoid ideation, compared to the control group (p < 0.05). Also, Internet addiction and daily use of the Internet as entertainment were significantly higher in online gamblers than non-online gamblers (p < 0.05). Also, a positive and significant correlation was found between the severity of gambling and the severity of Internet addiction, severity of depression, severity of anxiety, and severity of obsession in online gamblers (p < 0.05). Overall, online gambling is common in Iran and is associated with psychiatric problems. Health professionals and the government should pay special attention to online gambling and its related problems.

A Pilot Study of Gender Differences in Sexual Arousal of Patients With OCD: The Moderator Roles of Attachment and Contamination Symptoms

Sexual arousal is often impaired in patients with obsessive-compulsive disorder (OCD). However, little is known about the factors related to this impairment: no study focused on the role of gender-based effects of attachment styles and contamination symptoms. The Dual Control Model assumes three processes driving sexual arousal: sexual excitation (SE), sexual inhibition (SI) due to threat of performance failure, and SI due to threat of performance consequences (e.g., getting contaminated with sexually transmitted diseases). In a group of OCD patients, we hypothesized that (a) women report lower SE and higher SI than men; (b) patients with insecure (both anxious and avoidant) attachment styles show lower SE and higher SI; (c) attachment styles moderate the relation between gender and sexual arousal (respectively, for women, higher attachment anxiety, and for men higher attachment avoidance were related to impaired sexual arousal (higher SE and SI) controlling for OCD severity); and (d) contamination symptoms moderate the relation between gender and sexual impairment (women with contamination symptoms show impaired sexual arousal). Seventy-two OCD patients (37.50% women) completed the Obsessive-Compulsive Inventory-Revised, Attachment Styles Questionnaire and Sexual Inhibition/Sexual Excitation Scales. In contrast with our hypotheses, women reported higher SE and lower SI due to threat of performance consequences than men. Patients with higher attachment avoidance (discomfort with intimacy) but also confidence in self and others had higher SE. Women with attachment avoidance (i.e., discomfort with intimacy) had lower SE, while women with attachment anxiety (i.e., preoccupations with relationships) had higher SI due to negative performance consequences. Women with contamination symptoms had higher SI due to performance failure but lower SI due to performance consequences. The present preliminary findings suggest that sexual arousal impairment should be evaluated during the assessment of OCD patients, and gender-based effects of attachment styles and contamination symptoms should be considered during personalized treatment planning.

Obsessive-Compulsive Disorder and Decision Making under Ambiguity: A Systematic Review with Meta-Analysis

In the last decade, decision-making has been proposed to have a central role in obsessive-compulsive disorder (OCD) aetiology, since patients show pathological doubt and an apparent inability to make decisions. Here, we aimed to comprehensively review decision making under ambiguity, as measured by the Iowa Gambling Task (IGT), in OCD, using a meta-analytic approach. According to PRISMA Guidelines, we selected 26 studies for a systematic review and, amongst them, 16 studies were included in a meta-analysis, comprising a total of 846 OCD patients and 763 healthy controls (HC). Our results show that OCD patients perform significantly lower than HC at the IGT, pointing towards the direction of a decision making impairment. In particular, this deficit seems to emerge mainly in the last three blocks of the IGT. IGT scores in OCD patients under the age of 18 were still significantly lower than in HC. Finally, no difference emerged between medicated and unmedicated patients, since they both scored significantly lower at the IGT compared to HC. In conclusion, our results are in line with the hypothesis according to which decision making impairment might represent a potential endophenotype lying between the clinical manifestation of OCD and its neurobiological aetiology.

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

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.