Longitudinal relationships between specific domains of interoception and muscle dysmorphia symptoms.

Muscle dysmorphia (MD) is a subtype of body dysmorphic disorder (BDD); few risk factors for MD symptom development have been identified. One potential risk factor may be decreased interoceptive sensibility (impaired ability to recognize bodily sensations), which is present across a range of mental disorders. Notably, impaired interoceptive awareness is elevated in populations at-risk for MD. Furthermore, interoception is associated with MD symptoms, and theoretically, interoceptive dysfunction may facilitate engagement in MD symptoms. However, longitudinal research on interoception and MD is scarce, and specific MD symptoms implicated in these relationships are unknown. This study examined longitudinal relationships between specific domains of interoceptive sensibility and MD symptoms. Participants were 255 (26.7% Male; 72.1% Female; 1.2% Non-binary) undergraduates who completed two self-report surveys separated by four weeks. A path model was specified in which seven forms of interoception predicted five MD symptoms. Results suggested that interoceptive sensibility characterized by difficulties attending to bodily sensations and viewing these sensations as distracting predicted MD symptoms like muscle checking, positive attitudes towards using muscle-building substances, and compulsive exercise. Specific forms of impaired interoceptive sensibility may represent a risk factor for MD symptoms. If clinicians can increase the interoceptive abilities of their clients at risk for MD, this may prevent the development of MD symptoms.