ABSTRACT
Trauma exposure is a generalized risk factor for a number of psychiatric outcomes, including both posttraumatic stress disorder (PTSD) and substance use disorders (SUD), two disorders that frequently co-occur (e.g., Head et al., 2016; Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995; Petrakis, Rosenheck, & Desai, 2011). Comorbidity of PTSD and SUD may be conceptualized in three, nonexclusive ways: (1) PTSD plays a causal role in subsequent substance use, (2) preexisting substance use increases vulnerability to being exposed to trauma or developing PTSD following trauma, and/or (3) concurrent onset of PTSD and SUD in the aftermath of a trauma (Brady, Back, & Coffey, 2004). Although trauma is a predictor of PTSD, SUD, and their comorbidity, trauma exposure is not a sufficient condition, as the majority of trauma survivors do not develop negative mental health outcomes (Kilpatrick et al., 2013). Variability in response to trauma has led researchers to explore individual differences that may account for risk, with evidence that joint risk for PTSD and SUD is at least partially influenced by a common set of genetic risk factors (Jang, Stein, Taylor, Asmundson, & Livesley, 2003).
