In the present study we confirmed our hypothesis that GABRA2, childhood trauma and their interaction influence vulnerability to substance dependence, at least in African American men. Firstly, we found that the patients with heroin, alcohol and cocaine dependence had experienced significantly more childhood trauma than the controls. Furthermore, our results showed that the greater the severity of childhood trauma the greater the likelihood of polysubstance dependence. The latter finding is supported by previous studies (37). Secondly, our results showed that GABRA2 variation predicted addiction vulnerability, particularly for heroin dependence. Thirdly, an interaction between childhood trauma and GABRA2 variation was found to influence addiction risk, particularly for cocaine dependence.
