Here, among 3,013 substance-naïvea children (age=9.92±0.62 years, 47% Female; 100% genomically-confirmed European ancestry; Supplemental Table 1) who completed the baseline session of the ongoing Adolescent Brain Cognitive DevelopmentSM Study (ABCD Study®; data release 2.0.1), we test whether PRS for alcohol use and problematic use (including alcohol use disorder) are associated with brain structure phenotypes. To this end, we generated PRS using the largest available GWASs of alcohol use (i.e., alcohol drinks/week [DPW-PRS]; training n=537,349) and problematic use (i.e., alcohol use disorder/problem use [PAU-PRS]; training n=352,365) and estimated their association with total and region variability in cortical thickness, cortical surface area, cortical volume, subcortical volume, as well as white matter volume and integrity, among substance naïve children. Due to divergent findings among adults with AUD and children at familial risk for AUD (2,8), we tested all regions with correction for multiple testing. We tested whether any observed associations were present in substance naïve children of African ancestry (n=997), with polygenic risk scores generated using summary statistics generated from individuals of African ancestry (n= 62,447). Finally, we expected that variability in brain
