Role of Genetic Risk in the Association Between Screen Time and Child Development

Abstract

To the Editor We recently published a study on data from the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study that showed screen time for children aged 1 year was associated with developmental delays in communication and problem-solving skills domains at ages 2 and 4 years. 1 We focused on the association and could not address whether long screen time is associated with developmental delay directionally or is a characteristic of children with developmental delay. Thus, we were curious about the direction of the association between screen time and child development.Madigan et al 2 conducted an innovative analysis using a random-intercept cross-lag panel model that supported the directional association between screen time and development in children. Other studies focusing on children's genetic risk have reported that the genetic risk of autism spectrum disorder or attention-deficit/hyperactivity disorder is associated with long screen time. 3,4 These studies on genetic risk suggest the possibility that long screen time is a characteristic of children with developmental delays. 3,4 Under such circumstances, Yamamoto et al 5 published a study that examined the associations between screen time and children's development, focusing on the direction of the association by the random-intercept cross-lag panel model. This research is important because it replicates and updates the results of the study by Madigan et al. 2 In particular, we are interested in the finding of Yamamoto et al 5 that bidirectional associations were found only in the communication domain of the 5 developmental domains investigated. These results support our previous findings, which highlighted that the associations between screen time and child development should be examined by developmental domain. 1 To examine the association in more detail, Yamamoto et al 5 use various variables for environmental factors related to screen time and children's development, such as maternal psychological distress and the presence or absence of older sib-lings. On the other hand, the association may be captured in more detail if genetic information is considered. This is because it has been shown that children with a genetic risk for developmental delay typically have longer screen time. 3,4 Thus, genetic risk of developmental delay could be a confounding factor in examining the association between screen time and children's development. We believe it is difficult to narrow the bidirectional association between screen time and child development to unidirectional without adjusting for its genetic risk. Future studies that consider the genetic risk of developmental delay are warranted to further the discussion on screen time and children's development.