Do genetics add to screen time effects?

DNA patterns could be one of the reasons why kids who spend lots of time on screens often have more attention or emotional issues, according to new research.

The study, published 6 November in JAMA Network Open, compared the impact of screen time and genetics in more than 4200 children, revealing that genes were involved in most of the observed links between attention issues and screen time, and 42% of the observed links between emotional issues and screen time.  

The researchers noted that if their results held up, then restricting childhood screen time could be a less effective tool to prevent attention and emotional issues than expected.  

Lead author, Dr Henning Tiemeier, from Harvard, explained that the team assessed the single-nucleotide polymorphism-based heritability of screen time, attention problems, and the internalisation of problems using a genetic sensitivity analysis model (Gsens). 

Family income, highest parental educational level, and maternal psychopathological disorder were also included, and the team adjusted the model for the top 10 principal components to account for residual confounding by genetic ancestry. 

The sample included 4262 children, of whom 1993 were females (46.8%) and 2269 were males (53.2%) with a mean baseline age of 9.9 years. Children reported a mean daily screen time of 3.2 hours but using a shorter questionnaire capturing only approximate screen use hours, parents reported a mean screen time of 1.2 hours per day for their children.  

“First, increased child screen time was associated with increased psychiatric problems, an association that was partially explained by sociodemographic factors and maternal psychopathological disorder but largely remained after the adjustments,” Dr Tiemeier said. 

“Second, we found specificity in associations between PRSs and their corresponding traits, such as the television time PRS having higher association with child screen time compared with other traits.  

“However, we also found associations between PRSs and other traits, such as the television time PRS being a factor in both attention and internalizing problems, suggesting horizontal pleiotropy of the genetic variants and thus a possible genetic predisposition that could be a factor in more screen time and psychiatric problems.” 

The association between screen time and attention problems was highly confounded by genetic factors, while the association between screen time and internalizing problems was also genetically confounded, but to a much lesser degree. 

The proportion of genetic confounding remained comparable even after additionally adjusting the models for socioeconomic status.  

“Overall, our results highlight the importance of considering genetic factors in socio-behavioural research, as considering genetic factors helps in better understanding complex causal associations,” Dr Tiemeier concluded. 

“Many policymakers and scientists view child screen time as a modifiable risk factor.  

“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. 

“This finding does not suggest that parents should adopt a lenient attitude toward children who use electronic devices excessively, as increased screen time could be factors in other risks, such as reduced physical or academic activities.”