Associations between the environment, brain, mental health, and cognition across adolescence

Adolescence is a critical period for the development of the brain, cognition, and mental health, which are shaped by a wide range of environmental factors. In the present study, we analysed the Adolescent Brain and Cognitive Development (ABCD) dataset to examine how a range of proximal (e.g., socioeconomic status, familial circumstances) and distal (e.g., neighbourhood conditions, access to healthcare and education) environmental factors are associated with changes in centile-based measures of brain structure, and whether these brain differences subsequently mediate variations in cognition and mental health. We analysed these associations both at baseline (N = 6,911; 3,605 M, 3,606 F; mean age = 9.93) and longitudinally across three timepoints (N = 1,628; 879 M, 749 F; ages 8-15). At baseline, a more advantaged proximal and distal environment was associated with larger volumes across the whole brain relative to age- and sex-matched peers, which, in turn, mediated better mental health outcomes and cognitive performance. In the longitudinal analysis, the childhood environment predicted changes in brain structure across adolescence, and these structural changes predicted changes in mental health and cognition. The childhood environment also predicted cognitive but not mental health changes across adolescence, suggesting that these associations may already be established early in adolescence. These findings provide insight into how environmental and neural factors shape adolescent mental health and cognition, with potential implications for early intervention strategies aimed at promoting positive developmental outcomes.