Examining the bidirectional relationship between physical activity, screen time, and symptoms of anxiety and depression over time during adolescence

Abstract More physical activity (PA) and less screen time (ST) are positively associated with mental health in adolescents; however, research is limited by short-term designs and the exclusion of ST when examining PA. We examined: (a) changes in PA, ST, symptoms of depression, and symptoms of anxiety over four assessments spanning 11 years, and (b) bidirectional relationships between initial PA, ST, and symptoms of depression and anxiety as predictors of change in each other during adolescence. Between 2006 and 2010, participants from Ottawa Canada (Time1; N  = 1160, Mean age = 13.54 years) completed questionnaires at four points covering the ages from 10 to 21 years. Latent growth modeling was used. PA decreased over time whereas ST and symptoms of depression and anxiety increased over time. Controlling for sex, ethnicity, school location, zBMI, birth year, and parents' education, initially higher anxiety was associated with initially higher ST (covariance = .88, p p  = .07) independent of initial symptoms of depression. Higher initial depression was associated with higher initial ST (covariance = 2.55, p p  = .06) and increases in depression (covariance = .41, p p