Objective: Many women receiving substance use treatment report histories of interpersonal violence (IV) victimization, including physical and sexual assault. IV is a risk factor for mental and behavioral health difficulties such as posttraumatic stress disorder (PTSD) and substance use disorder (SUD). Consistent with the self-medication hypothesis, PTSD may explain elevated SUD among IV survivors. Yet, few studies have investigated whether PTSD may have differential mediating effects for different substances, which has significant treatment implications. Methods: In 124 women (M age = 35.37, SD = 11.90) in substance use treatment, we examined PTSD symptoms as a mediator between IV and severity of different types of substance use, including alcohol, cannabis, cocaine, and opioid use. Participants completed self-report measures including the ASSIST, PCL-5, and LEC-5. Data were analyzed using path analysis in Mplus 8.3. Both dichotomous and continuous outcomes of problematic substance use outcomes were examined. Results: Most women (53.3%) reported problematic substance use with at least one substance, including opioids (39.7%), cocaine (13.0%), alcohol (9.6%), and cannabis (5.6%). Most (83.2%) of the sample reported at least one IV incident. On average, women reported clinically significant PTSD symptom severity. When problematic substance use was examined dichotomously, findings revealed significant indirect effects from IV exposure to opioid (β = 0.10, p = .010) and cocaine use (β = 0.07, p = .039) via elevated PTSD symptoms. There were no significant indirect effects for problematic alcohol (β = 0.03, p = .260) or cannabis use (β = 0.02, p = .562). When substance use was examined continuously, results revealed significant indirect effects from IV exposure to opioid (β = 0.09, p = .017), cocaine use (β = 0.09, p = .015), and alcohol use (β = 0.08, p = .020) via elevated PTSD symptoms. Indirect effects for cannabis use remained nonsignificant (β = 0.05, p = .100). Conclusions: IV survivors may be particularly at risk for opioid and cocaine misuse because of elevated PTSD symptoms. Treatments that integrate PTSD and SUD are needed to simultaneously target traumatic stress and substance use. Women with opioid and cocaine misuse may particularly benefit from trauma-focused exposure-based psychotherapy to reduce symptoms of PTSD, and thus, decrease opioid and cocaine misuse.
Keywords: Interpersonal violence; physical assault; posttraumatic stress disorder; sexual assault; substance use disorder.