number 1 ever happen to you?”). Respondents were then asked which event was most disturbing, and the assessment of lifetime PTSD focused on the identified event. Additional demographic information and DSM-IV diagnostic data were also obtained using interview sections modified from the SSAGA. To decrease respondent burden, sections of the interview (including the depression section) that were unchanged from a recent assessment were not readministered to twins or siblings interviewed in partially overlapping genetic studies (2001-2005) that focused on nicotine and alcohol.33,34 For the present study, the diagnosis of MDD was obtained from the Childhood Trauma Study for 2042 individuals; the previous assessment provided this diagnosis for the remaining 537 participants. The assessment used to obtain cohort II data, reported herein as supplementary results, included a similar SSAGA-based MDD section and the National Comorbidity Survey–derived traumatic event list without the items assessing the diagnostic criteria for PTSD.
