1 Screen-Based Behaviors as Moderators of the Link Between Physical Activity and Internalizing and Externalizing Symptoms in Adolescents: A Population-Based Cohort Study

Background: Increased engagement in screen-based behaviors may contribute to decreased physical activity (PA) participation and is associated with mental health among adolescents. Yet, there remain knowledge gaps in how types and duration of screen-based behaviors may moderate the associations between PA, psychological distress, internalizing, and externalizing symptoms. This population-based study aimed to examine this relationship. Methods: Longitudinal data were obtained from the Millennium Cohort Study and adolescents were followed up from the 14-year to 17-year waves. Data on device-based moderate to vigorous PA (MVPA), screen-based behaviors (watching videos and playing videogames), internalizing (emotional and peer problems) and externalizing symptoms (hyperactivity and conduct problem), and psychological distress were analyzed using negative binomial regression (stratified by gender) with interaction terms of continuous device-based PA and categorical screen-based behaviors being applied. Results: The final sample included 3397 adolescents (mean age = 13.8, 54% girls). Device-based MVPA was associated with a lower incidence of emotional problems (boys [incidence rate ratio (IRR) = 0.97], and girls [IRR = 0.98]), peer problems (IRR = 0.97), and psychological distress (girls only, IRR = 0.98). Video watching for ≥2 hours per day was associated with a higher incidence of conduct problem in boys (IRR = 1.20) and videogames playing ≥2 hours per day was associated with all internalizing and externalizing symptoms in girls (IRR range 1.10–1.21). A buffering effect of MVPA on various symptoms among those spent <2 hours per day on screen-based behaviors was observed. Conclusions: Reducing screen-based behaviors may help maximize the benefits of MVPA on mental health outcomes in adolescents therefore implementing interventions targeting screen-based behaviors reduction should be recognized as first-line priority.