Extracurricular activities shape children’s development, yet how the interaction between their modality (digital/physical) and social context (social/non-social) impact mental health and neurodevelopment remains unclear. This study examined these relationships and their bidirectionality, as well as mediation by brain structural changes. Using baseline and one-year follow-up data from 8230 children in the Adolescent Brain Cognitive Development Study, we analyzed self-reported screen time for six digital activities (three social, three non-social), caregiver-reported participation in 28 extracurricular activities (11 social, 17 non-social), mental health via the Child Behavior Checklist and Kiddie Schedule for Affective Disorders and Schizophrenia, and gray matter volume using T1-weighted MRI. Distinct interaction patterns between modality and social context emerged. Physical-social activities were linked to fewer psychiatric symptoms, particularly withdrawn/depressed behaviors, and increased frontoparietal gray matter. In contrast, digital non-social activities were associated with higher psychiatric risk, especially rule-breaking behaviors, and reduced temporal gray matter. Physical non-social and digital-social activities demonstrated mixed effects on developmental measures. Longitudinal analyses revealed bidirectional activity-mental health associations, with brain volume changes mediating 3.7–5.0% of these relationships. These findings highlight the interactive role of activity modality and social context in children’s development and provide neurobiological evidence informing guidelines for beneficial developmental outcomes.
Tian et al. (2026) studied this question.