There are a few limitations to this study. The CTQ is a self-report questionnaire although it has been shown to have high reliability and validity (Bernstein et al., 1994, 1997, 2003; Bernstein and Fink, 1998; Scher et al., 2001; Thombs et al., 2007). The nature and severity of each suicide attempt was not systematically recorded. Since the complete SCID was not administered, data about possible comorbid disorders such as depression, anxiety disorders and PTSD was not available. Although the sample size decreased to 474 (112 suicide attempters) when examining G × E interactions, it is important to note that the participants in this study had for the most part been exposed to considerable childhood trauma and this could increase the strength of G × E interactions. For example, using the dichotomous CTQ clinical cut-off scores that differentiate between the presence or absence of significant abuse/neglect (Walker et al., 1999) we found that only 27% of individuals did not meet criteria for significant abuse/neglect. Finally this study was performed in African Americans predominantly with substance dependence and it is not clear that the results can be generalized to other populations or other patient groups.
