All interviews were conducted in person by experienced trained interviewers. Diagnostic sections on illicit drug and alcohol dependence, and major depressive disorder were modified from the Semi-Structured Assessment for the Genetics of Alcoholism - Australia (SSAGA-OZ) (Bucholz et al., 1994; Hesselbrock et al., 1999). The assessment of lifetime DSM-IV PTSD was modified from the National Comorbidity Survey (NCS) (Kessler et al., 1995) interview which itself was derived from the Revised Diagnostic Interview Schedule (Breslau et al., 1991). The NCS assessment, for which excellent psychometric properties have been reported (Kessler et al., 1995), first asks respondents whether they had ever experienced a series of traumatic events. Respondents are then asked which event was most disturbing and the assessment of lifetime PTSD focuses on the identified event. Additional non-diagnostic sections of the interview included SSAGA-OZ demographics and suicidal thoughts and behavior sections and a screening instrument for borderline personality, adopted from the International Personality Disorder Examination (IPDE) (Loranger et al., 1994). The Barratt Impulsiveness Scale (BIS), a 30-item self-report questionnaire (Patton et al., 1995; Maloney et al., 2009), was added to the assessment protocol after data collection had begun and is thus only available on a subset of participants (N=1315).
