Genetic and environmental influences on structural brain development from childhood to adolescence: A longitudinal twin study on cortical thickness, surface area, and subcortical volume

The human brain undergoes structural development from childhood to adolescence, with specific regions in the sensorimotor, social, and affective networks continuing to grow into adulthood. Genetic and environmental factors may lead to individual differences in these brain trajectories, but it is understudied to what extent. The present longitudinal study used up to three biennial MRI scans (n=485) to assess the extent of genetic and environmental effects on brain structure (age 7) and development (ages 7-14) in sensorimotor, social, and affective network regions. Heritability estimates varied across brain regions. All regions were genetically influenced (ranging from 18-59%), with additional shared environmental factors affecting the primary motor cortex (30%), somatosensory cortex (35%), DLPFC (5%), TPJ (17%), STS (17%), precuneus (10%), hippocampus (22%), amygdala (5%), and nucleus accumbens (10%). Surface area was more genetically driven (38%) compared to cortical thickness (14%). Longitudinal brain changes were primarily driven by genetics (ranging from 1-29%), though shared environment factors (additionally) influenced the somatosensory cortex (11%), DLPFC (7%), cerebellum (28%), TPJ (16%), STS (20%), and hippocampus (17%). Surface area development had a higher shared environmental contribution (12%) than cortical thickness (6%). These findings underscore the need for further exploration of brain-behavior associations and the role of enriched and deprived environments from childhood to adolescence. Ultimately, our study can inform interventions to support children's development.