NEW YORK – New research from a team led by investigators at the Harvard T.H. Chan School of Public Health suggests that genetic contributors to psychiatric problems overlap with those involved in childhood screen use.
"Results of this study suggest that genetic confounding may explain a substantial part of the associations between child screen time and psychiatric problems," investigators wrote in JAMA Network Open on Monday, noting that such confounding "should be considered in sociobehavioral studies of modifiable factors for youth mental health."
"Many policymakers and scientists view child screen time as a modifiable risk factor," the authors noted. "However, if genetic factors account for a large part of the observed association between screen time and mental health, then interventions restricting child screen time could be less effective in preventing child attention and internalizing problems than expected, consistent with similar findings on genetic confounding in the association between social media use and mental health."
For their study, the researchers analyzed genotyping profiles and questionnaire-based, self-reported screen time data collected at almost two dozen Adolescent Brain Cognitive Development Study sites in the US from 2016 to 2019, focusing on 4,262 children between the ages of 9 and 11 years old.
The team also considered Achenbach Child Behavior Checklist-based parental assessments of the children's attention and internalizing problems at a one-year follow-up point, digging into potential confounding between screen time and psychiatric traits with a genetic sensitivity analyses model that took available polygenic risk scores (PRS) for screen time, attention-deficit/hyperactivity disorder (ADHD), and depression into account.
Though high amounts of screen time did coincide with higher-than-usual rates of attention deficit or internalizing problems, the investigators also saw cross-trait associations between PRS for screen time, attention, and internalizing traits.
"The main finding is that a shared genetic risk may underlie the association between screen time use and ADHD symptoms," senior and corresponding author Henning Tiemeier, a researcher at the Harvard T.H. Chan School of Public Health, said in an email. "This means that this consistently observed association can likely be explained by underlying genetic risk patterns; we interpret this as genetic confounding."
Both screen time use and ADHD have been linked to a large suite of small-effect variants, Tiemeier explained. But the team's findings highlighted potential horizontal pleiotropy of the genetic risk, rather than supporting a model where genetic contributors lead to enhanced screen time, which in turn results in ADHD.