For the current analyses, data from a cohort of 3,618 individuals (“September 2017” data freeze), who were aged 12–26 years at their baseline (i.e., first) interview, and comprised the longitudinal component of COGA, were used32. Briefly, participants were offspring of COGA families, with 61.6% having one parent with alcohol use disorder. Since 2004, participants have been interviewed every 2 years with the same structured interview; follow-up interviews are ongoing. We included only subjects with GWAS data and of European-American (EA; as verified by genotype) descent to match the ethnicity of the discovery GWAS13 (n=1,897); of these individuals, 1,840 had non-missing data for relevant variables. For the longitudinal growth curve analyses, a further reduction in sample size resulted from sub-setting on those who were EA, had GWAS data, and had 3 or more assessments, including the baseline assessment (final analytic n = 1,167). When compared to the larger subset of 1,840 individuals, those with 3 or more assessments did not vary of any demographic or cannabis-related characteristics, suggesting that selection for those with ≥3 assessments did not significantly bias findings (Table S1).
