Transactional Associations Between Physical Activity and Depressive and Anxious Symptoms in Adolescent Girls and Boys: Considering Screen Time and Sleep Duration.

The nature of the associations between physical activity and depressive and anxious symptoms, as well as the differences between adolescent girls and boys, remain poorly understood. The benefits of physical activity may depend on other lifestyle habits, including screen time and sleep duration, but the mechanisms underlying these associations have not often been explored. Thus, the present study aimed to examine (1) the bidirectional associations between physical activity and depressive and anxious symptoms during adolescence while controlling for screen time and sleep, (2) whether these associations are mediated by screen time and sleep, and (3) sex differences. The variables used were mostly self-reported by participants of the Québec Longitudinal Study of Child Development at ages 13, 15 and 17 (N = 1556). Random intercept crosslagg panel models and multigroup analyses were conducted. A high level of physical activity significantly but weakly predicted a low level of depressive symptoms from 15 to 17 in girls and boys. Physical activity was also associated with less screen time in girls aged 13 to 15, and in everyone aged 15 to 17. No associations between physical activity and anxious symptoms were found significant. The sample is more representative of White Quebec adolescents from a higher socioeconomic status, from 2011 to 2015. In conclusion, among all life habits, promotion of physical activity should be a part of prevention efforts for depression in youth, especially among older adolescents. Physical activity could also be promoted to reduce screen time in adolescents, and earlier for girls.