was dropped from these analyses) and the presence of at least one rs12364283 G allele as follows: both amphetamine dependence and the rs12364283 G allele present; amphetamine dependence alone, and the rs12364283 G allele alone (those with neither amphetamine dependence nor a copy of the rs12364283 G allele served as the comparison group). Post-hoc analyses that included sex and heroin dependence case status as independent (control) variables were performed in SAS 9.2 to examine risk for PTSD (dependent variable) associated with these dummy variables. These analyses were repeated with inclusion of BIS total score as a covariate to determine whether self-reported impulsivity mediated these relationships in the sub-sample (N=1315) who had this measure available.
