Perception of social experiences and cortical thickness change together throughout early adolescence: Findings from the ABCD cohort.

Early adolescence is a dynamic period of social and brain development amid rapid hormonal and puberty changes. We examined how differences and changes in positive social experiences and cortical thickness co-develop from age 9-11 and 11-13 years in the ABCD cohort (N~12,000). We used bivariate latent change score models to capture cortical development (modeling mean whole-brain cortical thickness) and positive social experiences (modeling caregiver monitoring, family cohesion, prosocial behavior, number of friends, school engagement, school involvement, and neighborhood safety). We found evidence for correlated change, such that a greater reduction in positive social experiences was associated with a greater decrease in cortical thickness (est = 2.54,SE = .54, z = 4.74,p< .001, standardized effect size = .08), which did not differ between males and females in early and late puberty stages. We found mixed evidence for sex-specific relationships between puberty stage and social experiences, highlighting the need to better understand males' puberty and social experiences in early adolescence. The evidence supports a transactional model of development in that positive social experiences and cortical thickness change together throughout early adolescence. The findings also highlight the importance of supporting youth in early adolescence through school transitions.