Mental Health
Pubertal Timing and Depression: The Mediating Effects of Physical Activity and Body Dissatisfaction Dana Tarif* Dana Tarif Carol Joinson Abigail Fraser Jon Heron Ahmed Elhakeem
Background: Early pubertal timing has been found to be associated with adverse mental health outcomes, including depression. Although the majority of research has focused on girls, evidence suggests that early puberty is associated with depression in both sexes. However, the mechanisms underlying these associations remain unclear. Physical activity, a known protective factor against depression, has been found to be lower in early-maturing girls, while body dissatisfaction has been found to be higher in early-maturing girls and boys. This study aims to examine the potential mediating effects of physical activity and body dissatisfaction on the relationship between pubertal timing and depression in both sexes.
Methods: Data were analysed from 3806 (47% male) participants in a UK-based prospective cohort study, the Avon Longitudinal Study of Parents and Children (ALSPAC). Pubertal timing was assessed using age at peak height velocity (aPHV – males and females) and age at menarche (AAM), derived from repeated measurements collected from 7 to 17 years. Depression at 18 years was measured using the Clinical Interview Schedule-Revised (CIS-R). Mediators included accelerometer-measured physical activity (14 years), recorded as total counts per minute, and self-reported body dissatisfaction (14 years), measured using the Satisfaction and Dissatisfaction with Body Parts Scale. Confounders included socioeconomic status (SES), pre-pubertal BMI (9 years), adolescent BMI and depressive symptoms (13 years).
Analysis Plan: The analysis will include multivariable regression followed by counterfactual mediation analyses, using the parametric g-computation formula. We will evaluate the mediating effects of physical activity (model 1) and body dissatisfaction (model 2) on the association between pubertal timing and depression stratified by sex. Results will be adjusted for baseline and intermediate confounders. Findings from regression and mediation analyses will be presented.