Enhancing the Understanding of Muscle Dysmorphia as a Construct in Men: Examining Symptomatology, Classification, and Mechanisms of Risk

Abstract

Eating disorders represent a significant proportion of the global disease burden from psychiatric illnesses. Whilst men account for over a third of eating disorder cases in Australia, they are rarely included in eating disorder and body image research. This is particularly evident for Muscle Dysmorphia (MD), a disorder characterised by the perception that the body is insufficiently muscular and lean, which disproportionately effects men. Debate regarding the clinical features and definition of MD has been ongoing, with a need for research that aims to understand the construct to inform its diagnosis, classification, and development to guide practice. The current program of research aimed to address these gaps by developing a deeper understanding of the MD construct. Specifically, it aimed to (i) investigate the latent structure of the MD construct and how its symptoms manifest across a full severity continuum; (ii) provide clarity on where MD should be classified in diagnostic systems by examining the relationship between MD symptoms and those of related disorders (eating disorders, obsessive-compulsive disorder and body dysmorphic disorder), and (iii) identify mechanisms that may influence the progression of MD symptoms. These aims were examined through a series of three studies utilising self-report data from a large sample of men recruited from the community (N = 510) to represent the full range of symptoms. The research program utilised a range of complex statistical approaches, including exploratory and confirmatory factor analysis, item response theory, assessment of covariance between MD and related construct measurement models, bifactor analysis, and hierarchical regression with moderation. Results from Study 1 indicated the MD construct comprised five factors, including supplement and substance use, maladaptive eating and impairment, obligatory exercise, drive for size and drive for leanness, furthermore, these symptoms operated along a severity continuum Findings from Study 2 initially indicated that MD is significantly more associated with EDs, and OCD compared to BDD. However, once the shared variance across the four disorders was accounted for, MD displayed a significantly higher relationship with ED compared to OCD and BDD. Study 2 also revealed that three out of the five MD features are distinct or more distinct than shared (drive for size, drive for leanness, supplement and substance use). Study 3, which investigated three body-related contingencies of self-worth as risk factors amplifying the association between cognitive and behavioural indicators of MD, yielded support for muscularity-based self-worth as a specific vulnerability factor. In particular, by strengthening the links between drive for leanness and obligatory exercise, as well as drive for size and supplement and substance use. The findings from this research program have important implications for research and practice. Firstly, this program of research suggests expanding the MD construct to include symptoms pertaining to the five factors and acknowledging that these symptoms operate along a severity continuum. This program of research also identified that it is the presence of muscularity-based self-worth that can turn 'normative' desires to be more muscular and lean into engagement in pathological behaviours (obligatory exercise and supplement and substance use). Overall our research highlights that that the current specifier used to diagnose MD within the BDD criteria in the Diagnostic Statistical Manual of Mental Disorders Fifth Edition, Text Revision (DSM-5-TR) warrants further consideration given MD was found to be significantly more associated with OCD and eating disorders. This research has implications for how we conceptualise, assess, diagnose, and treat MD in men. It offers novel insights into the development of screeners, assessment tools, as well as potential prevention, early intervention, and treatment programs for MD. Show more