At T1, adolescents’ FHD of alcohol and drug use disorder were calculated separately using methods of Zucker et al. [52] and Stoltenberg et al. [53]. The Computerized Diagnostic Interview Schedule [54] and family member report on the Family History-Research Diagnostic Criteria [55] determined lifetime alcohol and drug disorder (either DSM-III-R or DSM-IV) of adolescents’ grandparents and parents. To minimize missingness, data were required from 1 parent and 2 grandparents. Grandparents’ lifetime alcohol or drug disorder was weighted by 0.25, parents’ by 0.5, and relatives without substance disorder by 0. Summed scores were rescaled from 0 to 2 and averaged to form an FHD composite, which was a covariate (see Table 1).
