Music participation, global cortical morphometry, and later language outcomes in the ABCD study.

Introduction: Associations between music participation and language outcomes in children have been widely reported, yet whether cortical morphometry statistically accounts for these relationships remains unclear, particularly at the population level. Methods: Using longitudinal data from the population-based Adolescent Brain Cognitive Development Study, we examined whether music participation at ages 9-10 years was associated with language outcomes at 2-year follow-up and whether global cortical morphometry statistically accounted for part of these associations. The analytic sample included 5,993 children, including a twin subsample of 936 children used for sensitivity analyses. Music participation was assessed using parent-reported measures of sustained participation and practice intensity. Language outcomes were assessed at 2-year follow-up using NIH Toolbox measures of picture vocabulary, oral reading recognition, and crystallized cognition. Candidate mediators included baseline global cortical surface area, total cortical volume, mean cortical thickness, and mean sulcal depth. Linear mixed-effects models and mediation analyses were adjusted for baseline language performance and a prespecified set of demographic, socioeconomic, prenatal/perinatal, behavioral, extracurricular, and site-related covariates. Results: Sustained music participation was associated with higher crystallized cognition, picture vocabulary, and oral reading recognition scores at 2-year follow-up, with adjusted standardized differences ranging from 0.08 to 0.17 standard deviation units. Global cortical surface area and volume, but not cortical thickness or sulcal depth, statistically accounted for 4.1%-8.1% of these associations. Each 1-standard-deviation increase in practice intensity was associated with slightly higher crystallized cognition and picture vocabulary scores, with adjusted standardized differences ranging from 0.04 to 0.06 standard deviation units, but was not associated with oral reading recognition. For the two significant outcomes, global cortical surface area and volume statistically accounted for 4.6%-6.5% of the observed associations. In the twin subsample, sustained music participation remained positively associated with all three language outcomes, whereas practice intensity was not significantly associated with any language outcome. Discussion: These findings provide longitudinal, population-based evidence that real-world music participation may be a relevant environmental correlate of language development in late childhood and that global cortical morphometry may statistically account for a small but measurable proportion of these associations.