The Collaborative Study on the Genetics of Alcoholism (COGA) was designed to investigate the genetic underpinnings of AUDs and related mental health conditions21–24 (details in online supplementary material and related publications22,23). Individuals were assessed using the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA)—only those using cannabis at least 21 times in a year (SSAGA I, II), or at least 11 times (lifetime; SSAGA IV), were asked follow-up questions about their cannabis-related experiences and were included in the current study. These cutoffs were a component of the SSAGA assessment instrument, similar to other diagnostic schedules. Diagnoses of schizophrenia and bipolar disorder were early exclusions for the COGA cohort21; thus, few, if any, individuals in this sample have a psychotic disorder diagnosis. Genotype data, covariates, and response to at least one cannabis-related experience were available on 4832 subjects (3128 of European ancestry and 1704 of African ancestry, determined via genetic principal components analysis; 42% female). The Institutional Review Boards at all sites approved this study, and all participants provided informed consent at every assessment.
