Data were collected by trained interviewers using an interview modified for telephone administration from the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA; Bucholz et al., 1994). The SSAGA was designed to assess the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 1994) substance use and other psychiatric disorders and related psychosocial domains. Consent was obtained verbally prior to the start of the interview. All available data from waves 1, 3 and 4 were utilized and collapsed across waves for purpose of analysis. The first reported age of onset given for trauma exposures, cannabis involvement, and other individual level covariates was utilized in analyses.
