Does the interpersonal theory of suicide explain relationships between muscle dysmorphia symptoms and suicidal ideation?

Muscle dysmorphia (MD) symptoms are robustly associated with suicidal thoughts/behaviors. Risk factors for suicidal ideation, such as perceived burdensomeness and thwarted belongingness, may help explain the relationship between MD symptoms and suicidal ideation. The current study extended past cross-sectional research by testing if perceived burdensomeness and/or thwarted belongingness mediated longitudinal relationships between MD symptoms and suicidal ideation. Two hundred and sixty-nine U.S. men recruited from Prolific completed self-report measures at three timepoints separated by one month each. Analyses used an adapted version of a longitudinal three-wave mediation model to test study hypotheses. Perceived burdensomeness mediated longitudinal relationships between MD symptoms and suicidal ideation. Thwarted belongingness did not show significant relationships with MD symptoms or suicidal ideation. Results extend past research by demonstrating that perceived burdensomeness may be a mechanism underlying longitudinal relationships between MD symptoms and suicidal ideation while establishing temporal ordering. Clinicians may consider targeting perceived burdensomeness in cases of comorbid MD/suicidality by using techniques that promote interpersonal effectiveness.