Associations between screen-time, physical activity and depressive symptoms differ based on gender and screen-time mode.

Higher levels of physical activity (PA) and screen time (ST) are associated with positive and negative mental health outcomes among adolescents, respectively. Research is needed to determine the interrelationship between ST and PA with depressive symptoms and the influence of ST modes. This study examines the associations between ST and PA level with depressive symptoms among 1756 adolescents (15.2 ± 1.6y; 995 female) in Ireland. Participants completed the Quick Inventory of Depressive Symptomatology and self-reported weekly ST (TV, computer, and phone use) and PA level (low, moderate, and high). Linear regressions examined associations between ST mode, PA level and relevant covariates with depressive symptoms in the full sample by gender, and in a sample stratified by PA level. Chi-square tests and one-way ANOVA examined gender differences in hours of ST, PA levels, and depressive symptoms. Differential associations were observed depending on the gender and ST mode. Higher levels of computer (β  =  0.106, p  ≤  0.000) and phone use (β  =  0.138, p  ≤  0.000) showed the strongest associations with depressive symptoms. PA level was inversely associated with depressive symptoms (β  =  - 0.175, p  ≤  0.000). When the sample was stratified by PA level, only associations between phone use and depressive symptoms were moderated by PA level for males and females. These findings highlight the complex interrelationships between ST, PA, and depressive symptoms, and that associations may vary based on gender and ST mode. This may have implications for future interventions. Increasing PA and reducing ST should be targeted concurrently with consideration given to different media and genders. Future research should explore longitudinal and prospective associations.