A modified version of the Semi-Structured Assessment for the Genetics of Alcoholism was used to assess DSM-IV psychiatric diagnosis (SSAGA-OZ; Bucholz et al., 1994; Heath et al., 2011). CSA was defined using 6 items that assessed unwanted exposure to another person's genitals, touching of breasts and/or genitalia, threats regarding sexual activity, and attempting to or having vaginal, oral, or anal sex, all prior to age 18. Items were averaged and then log-transformed to create a continuous CSA score (log-transformed: M = 0.09, SD = 0.11; untransformed: M = 0.26, SD = 0.34; raw: M = 1.57, SD = 2.04; distribution: 0 n = 806, 1 n = 184, 2 n = 114, 3n = 111, 4 n = 114, 5 n = 127, 6 n = 102). Our outcome variable of interest, cannabis dependence symptoms, was defined as the number of lifetime DSM-IV dependence symptoms reported2 (Table 3; M = 2.95, SD = 2.15). The distributions of dependence symptoms across genotype and CSA groups are given in the Supplement (Table S1).
