The Adolescent Brain and Cognitive Development (ABCD) Study is an ongoing multi-site longitudinal study of child health and development. The ABCD Study is led by the National Institute on Drug Abuse and measured children on a range of cognitive, behavioral, personality, and biological measures. These measures total in the several thousands and so a complete description of the is beyond the scope of this work (see the NIMH data archive: https://nda.nih.gov/data_dictionary.html?source=ABCD%2BRelease%2B3.0&submission=ALL, for more on the ABCD study see: Volkow et al. 2018 (14)). Our total sample at baseline includes 11,875 children, including 2,108 twins and 30 triplets, ages 8.9–11 were recruited from 22b sites across the United States, to complete the ABCD Study baseline assessment. We restricted our sample to participants of genomically-confirmed non-Hispanic European ancestry (n=4,737) who self-reported no exposure to substances and screened negative for substances according to toxicology, leaving a final analytic sample of 3,434 children (mean age =9.92 years, std age = 0.62, 47 % Female, n=3,013 with no missing data). Our African American sample consisted of 997 individuals (9.90 years of age, std age = 0.60, 49% Female) with 898 remaining after exclusion for substance exposure.
