The relationship between screen-based behaviors and adolescent mental health: a phenotypic and genetic analysis

BackgroundScreen use is linked to adverse mental health outcomes in adolescents, but differences across psychiatric diagnoses, mental symptoms, and types of screen-based activities remain unclear. Moreover, the extent to which genetic factors contribute to these associations is largely unknown. MethodsWe analysed longitudinal data from 23,790 adolescents (14-16 years of age) in the Norwegian Mother, Father, and Child Cohort Study (MoBa), linking questionnaire responses on screen use to registry-based psychiatric diagnoses and self-reported mental symptoms. Using regression models, we assessed associations between mental health outcomes and gaming, social media use, and TV watching. We also evaluated whether genetic liability to major psychiatric disorders, as indexed by polygenic risk scores (PRSs), was associated with screen use, and estimated the degree of genetic confounding using genetic sensitivity analyses. FindingsSpending 3-4 hours/day or more on any screen-based activity was associated with increased odds of a lifetime diagnosis of depressive, anxiety/stress-related, and hyperkinetic disorders. Similarly, minimal social media engagement was associated with increased odds of any psychiatric diagnosis, most strongly with pervasive developmental disorders. Associations with mental symptoms closely followed those observed for clinical diagnoses. The PRSs of major depression, anorexia nervosa, attention-deficit hyperactivity disorder, and autism spectrum disorder were significantly associated with screen use, suggesting shared genetic liability. Genetic sensitivity analyses indicated that a substantial proportion of the observed phenotypic associations may be attributable to genetic factors. InterpretationOur findings suggest a complex, bidirectional relationship between screen use and adolescent mental health, across both mental disorders and traits. Both high and low screen use may reflect underlying mental health vulnerabilities. The associations appear partly driven by shared genetic susceptibility, underscoring the importance of accounting for individual risk. These results support the need for individualized, context-sensitive digital media use guidelines. FundingResearch Council of Norway (Grant N{degrees}324499).