Brain structural co-development is associated with internalizing symptoms two years later in the ABCD cohort.

Greater youth engagement in SMA at ages 9-10 years statistically predicted higher levels of internalizing two years later. This association was mediated by cortical-brainstem circuitry, albeit with relatively small effect sizes. The findings may help delineate processes contributing to internalizing behaviors and assist in identifying individuals at greater risk for such problems.