Reciprocal longitudinal associations between symptoms of body dissatisfaction and disordered eating, self-harm and suicidal ideation

Background Eating disorders are severe psychiatric conditions associated with high mortality rates, particularly among young people. These disorders often co-occur with self-harm and suicidal ideation, yet the temporal dynamics between these variables remain poorly understood. Aims This study aims to elucidate the longitudinal associations between symptoms of body dissatisfaction and disordered eating, self-harm and suicidal ideation using structural equation modelling. Method Repeated measures of these phenotypes were used to construct a hypothetical model that includes cross-path analyses within and between the variables in two cohorts: the Twins Early Development Study (TEDS; ages 16, 21 and 26 years; N = 5196), representing a general population sample, and the COVID-19 Psychiatry and Neurological Genetics study (COPING; data collected between June 2020 and July 2021; N = 490), which focused on individuals with a history of anxiety or depression. In the TEDS cohort, symptoms of disordered eating, self-harm and suicidal ideation showed limited continuity across adolescence and young adulthood, with peak symptom severity at age 21 years. Results Cross-domain associations revealed that both self-harm and suicidal ideation at age 21 years were more strongly associated with disordered eating at 26 years than the reverse. In contrast, the COPING cohort exhibited greater stability in symptoms over time but showed minimal cross-domain effects. Conclusions The effects of self-harm and suicidal ideation on disordered eating in early adulthood are stronger than the influence of disordered eating on suicidality.