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. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement National Institute of Mental Health and Neurosciences. Grant Number: T32MH017119 National Institutes of Health and additional federal partners. Grant Numbers: U01DA041048, U01DA050989, U01DA051016, U01DA041022, U01DA051018, U01DA051037, U01DA050987, U01DA041174, U01DA041106, U01DA041117, U01DA041028, U01DA041134, U01DA050988, U01DA051039, U01DA041156, U01DA041025, U01DA041120, U01DA051038, U01DA041148, U01DA041093, U01DA041089, U24DA041123, U24DA041147 ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The ABCD study was performed in line with the principles of the Declaration of Helsinki. The University of California at San Diego (San Diego, CA, USA) Institutional Review Board was responsible for the ethical oversight of the ABCD study. Parents/caregivers and children completed written informed consent and written assent, respectively. The secondary analysis of the data was approved by the Research Ethics Committee for the Harvard University. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors