Indicators differed between adolescents and young adults due to developmental differences in substance use and externalizing behaviors (e.g. low incidence rate of AUD symptom endorsement among adolescents), and the use of different assessments in COGA based on age. For adolescents, indicators included: alcohol use, cannabis use, and DSM-5 (American Psychiatric Association, 2013) symptom counts of CD and ODD. All indicators for adolescents were obtained from the Child Semi-Structured Assessment for the Genetics of Alcoholism (C-SSAGA), an interview for children and adolescents based on the SSAGA and developed for COGA (Bucholz et al., 1994). Alcohol use was determined in the C-SSAGA by asking individuals to report frequency of past 12 months drinking on a 12-point scale. The scale was reversed from the original coding such that in the current study 1 indicated the lowest level of drinking (about 1 to 2 days) and 12 indicated the maximum level of drinking (every day). Non-drinkers were coded as zero. Cannabis use was coded as 1 (any use in the past year) or 0 (no cannabis use use).
