There are multiple theories about the relationship between drug use disorders and PTSD. One possible explanation is that drug users engage in risky and criminal behaviors making them more vulnerable to experiencing violent and traumatic events, thus elevating their risk of PTSD (Cottler et al., 1992). Alternatively, the self-medication hypothesis proposes that drugs are used to alleviate symptoms of painful traumatic experiences and PTSD (Brown and Wolfe, 1994; Chilcoat and Breslau, 1998a, b). Many studies indicate that trauma exposure is high in “hard” drug users (i.e., cocaine and opiates) and polysubstance users (Cottler et al., 1992; Johnson et al., 2006; Mills et al., 2005; Mills et al., 2006; Najavits et al., 1998). This may be explained in part by the high risk behaviors associated with the acquisition and use of these drugs, which lends evidence to support the first explanation described above. In the National Household Survey on Drug Abuse, those who used alcohol, cannabis, and cocaine were more likely to commit violent and non-violent crimes compared to those who used alcohol and cannabis only or alcohol only (Harrison and
