The associations of child screen time with psychiatric problems: the role of genetic confounding

Importance Children’s exposure to screen time has been associated with poor mental health outcomes, yet the role of genetic factors in this association remains largely unknown. Objective We examined (1) the longitudinal phenotypic association between child screen time and mental health outcomes and (2) the potential genetic confounding of this association. We hypothesized that genetics partially account for observed phenotypic associations. Design Longitudinal (baseline and one-year follow-up) population-based cohort. Setting Adolescent Brain Cognitive Development, 21 sites in the United States. Participants This study included 4,262 children of genetically assigned European ancestry with mean age 9.9 years [SD = 0.6 years], 46.8% female. Exposure Children’s daily screen time (in hours) was assessed both by child-report and parent-report questionnaires at baseline. Main Outcomes and Measures Child psychiatric problems, specifically attention and internalizing problems, were measured with the parent-rated Child Behavior Checklist at the one-year follow-up. We used Genetic sensitivity analyses (Gsens), based on structural equation models using polygenic risk scores (PRS) of both exposure and outcomes, and either single nucleotide polymorphism (SNP)-based heritability or twin-based heritability to estimate genetic confounding of associations between child screen time and attention or internalizing problems, separately. Results We found that child screen time was positively associated with the different psychiatric problems. Further, the television time PRS was associated with child screen time (β=0.18 SD, 95% CI: 0.14, 0.23); the ADHD PRS was associated with attention problems (β=0.13 SD, 95% CI: 0.10, 0.16); and the depression PRS was associated with internalizing problems (β=0.10 SD, 95% CI: 0.07, 0.13). These PRSs were associated with cross-traits, suggesting genetic confounding. Using PRSs and SNP-based heritability, we estimated that genetic confounding entirely accounts for the association between child screen time and attention problems, and moderately (42.7%) accounts for the association between child screen time and internalizing problems. When PRSs and twin-based heritability estimates were used, genetic confounding fully explained both associations. Conclusions and Relevance Genetic confounding may explain a substantial part of the associations between child screen time and psychiatric problems. Potential interventions to reduce screen time could be less effective in reducing psychiatric problems than previously hypothesized.