Environmental Suppression Mediates the Relationship between Posttraumatic Stress and Cannabis Use Among Trauma-Exposed College Students.

OBJECTIVE:Trauma exposure and posttraumatic stress (PTS) are prominent risk factors for problematic substance use, but little research has evaluated the mechanisms that link PTS and substance use. Emerging research supports the utility of reward probability (i.e., access to and pleasure experienced in response to environmental reward) as a mediator of the relationship between trauma and alcohol use problems. However, no existing studies have examined whether reward probability mediates the link between posttraumatic stress (PTS) and cannabis use in trauma exposed individuals. METHOD:In a cross-sectional design, undergraduate students (N = 404) anonymously completed online measures, the Reward Probability Index (RPI; Carvalho et al., 2011), the Posttraumatic Stress Disorder Checklist for DSM-5 (PCL5; Blevins et al., 2015), and the Cannabis Use Disorder Identification Test - Revised (CUDIT-R; Adamson et al., 2010), to satisfy course requirements. A parallel mediation path analysis model was used to test the hypothesis that RPI scales (Reward Probability, RP; Environmental Suppression, ES) would mediate the relationship between PTS and cannabis misuse. RESULTS:Findings revealed that RPI-ES fully mediated the relationship between PTS and cannabis misuse, whereas RPI-RP did not. CONCLUSIONS:Results support the utility of the RPI-ES scale as a transdiagnostic risk factor for both PTS and cannabis use and suggest further investigation into treatment approaches that optimize opportunities for (non-substance) rewarding experiences in the treatment of co-occurring PTS and substance misuse.