Getting shredded: Improving our understanding of muscle dysmorphia and related symptomology

Abstract

Muscle dysmorphia (MD) is a syndrome characterised by a preoccupation with one’s perception of their inadequate muscularity and engagement in risky body change behaviours to enhance muscularity. Recent systematic reviews examining MD have reported insufficient empirical support for the diagnosis, a lack of reliability in current diagnostic criterion, and inadequate delineation of MD from existing diagnoses. Considering the importance of accurate conceptualisation of psychiatric diagnoses for early screening and identification of symptomology as well as effective treatment and prevention, there is an urgent need to formulate an accurate clinical picture of MD. Consequently, this project sought to develop a clear clinical picture of MD to improve the assessment of MD and to extend our understanding of the classification of MD to inform future research and treatment protocols. This thesis comprised four original studies (one meta-analytic review and three empirical investigations) formulated to achieve these aims. The initial study was a systematic and meta- analytic review of research papers on MD utilising Robins and Guze’s (1970) criteria for validating psychiatric diagnoses. Our findings revealed that individuals with MD demonstrated more significant symptomology than controls indicating they likely fit a clinical diagnosis. Despite this, the symptomatic profiles, treatment response, and familial links of MD could not be meaningfully differentiated from traditional eating disorders (anorexia or bulimia nervosa) or body dysmorphic disorder. The subsequent original investigations included the development and preliminary psychometric evaluation of two novel measures, the Appearance and Performance Enhancing Supplement/Substance Scale (APES) and the Eating for Muscularity Scale (EMS) as well as a community-based study of muscle enhancing behaviours. These papers addressed ergogenic substance use, eating pathology, and body image disturbance, which had been identified from the initial review and Study 1 as potentially delineating MD from existing diagnoses. Studies 3 and 4 described the development and validation of the APES, an 18-item measure of supplement and substance use, as well as the EMS, a 30-item measure of muscularity-oriented eating pathology. The APES demonstrated strong internal consistency, medium to strong concurrent validity, and good to excellent test-retest reliability. Similarly, the EMS demonstrated high internal consistency, moderate to strong concurrent validity with associated measures, and strong test-retest reliability. Study 4 comprised an examination of the role of body image disturbance in predicting MD behaviours. This study, undertaken in a community sample of 265 participants, found that body image dissatisfaction, and not body image distortion, was associated with increased engagement with MD-related behaviours. Overall, our findings supported MD as a clinically relevant condition; however, we were unable to demarcate MD from existing diagnoses. Future research should utilise the APES and EMS as well as examine body image distortion to differentiate MD and similar psychiatric conditions. It is hoped that exploration of these areas, particularly within clinical populations, will continue to be a focus in research leading to increased knowledge regarding the aetiology, course, prognosis, heritability, and prevalence of MD to build more effective screening and treatment guidelines. Show more