Abstract
A growing body of work links posttraumatic stress disorder (PTSD) symptoms and substance use. Unfortunately, much of the literature has examined associations in isolation (e.g., alcohol only). Failure to account for simultaneous or concurrent substance use may limit conclusions that can be drawn from existing research, including the extent to which specific substances contribute differentially to PTSD symptom patterns. The current study examined differences in PTSD symptom profiles between individuals using one or both of the most commonly co-administered psychoactive substances - alcohol and marijuana. Trauma-exposed participants (N = 533; M(age) = 21.15) comprised two mutually-exclusive groups: past-month alcohol-only use (n = 334) or past-month alcohol and marijuana use (n = 199). Cluster-level and symptom-level profile analyses evaluated mean differences and shape (parallelism) of PTSD symptom severity profiles between the groups. Follow-up analyses examined symptom-specific difference in PTSD symptom endorsement and severity. Overall, individuals using marijuana and alcohol evidenced greater PTSD negative cognition (30.8% greater) and hyperarousal (26.4% greater) symptom severity. Alcohol and marijuana users were more likely to endorse, and report greater severity of, mood-related PTSD negative cognition symptoms (e.g., anhedonia, negative affect) and externalizing hyperarousal symptom (e.g., irritability/aggression, risky behaviors) than alcohol-only users. Findings highlight important PTSD differences between individuals that are often lumped into homogenous categories of isolated substance users. Findings provide preliminary support for an 'additive' self-medication model between PTSD and polysubstance use. Lastly, findings indicate that mood-related negative cognition symptoms and externalizing hyperarousal symptoms may be important targets for PTSD-polysubstance use intervention.