All participants completed the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) with an expanded assessment of cocaine dependence. When administered by trained interviewers, the SSAGA has good reliability in assessing substance abuse and dependence and other psychiatric disorders (Bucholz et al., 1994; Bucholz et al., 1995). A module from the Diagnostic Interview Schedule for DSM-IV (DIS-IV), a structured assessment that evaluated the presence or absence of psychiatric disorders according to the DSM-IV criteria (American Psychiatric, 2000; Robins et al., 2000) was used to evaluate PTSD. A history of fifteen specific traumatic events were queried including rape or sexual assault, assaultive violence (e.g., shot, stabbed), witnessing trauma to others, and non-violent trauma (e.g., serious accident, sudden death of a loved one). The traumatic events were assessed using closed-ended questions (e.g., Have you ever been raped or sexually assaulted?) with nominal response options (i.e., Yes or No). Participants were asked to select the most distressing event and were subsequently evaluated for symptoms of PTSD. A diagnosis of PTSD was dependent on Criterion A, which required intense fear, helplessness, or horror in
