Abstract
BACKGROUND: Accumulating evidence indicates a link between post-traumatic stress disorder (PTSD) and cannabis use and suggests that this link may vary as a function of the PTSD symptom cluster type. Consistent with negative reinforcement models of substance use, individuals with elevated Cluster D (Hyperarousal) symptoms may be more likely to use cannabis in response to elevated state anxiety and experience decreases in state anxiety after using cannabis. OBJECTIVES: We aimed to test hypotheses that the interaction of Cluster D and state anxiety would be related to subsequent cannabis use and that those with elevated Cluster D symptoms who used cannabis would report the greatest decreases in state anxiety. To test the specificity, we tested whether Clusters B (re-experiencing) and C (avoidance) showed similar relationships. METHODS: The present study used ecological momentary assessment to examine cannabis use among 87 cannabis-using individuals with PTSD symptoms (64.4% male, 56.3% non-Hispanic Caucasian). State anxiety and cannabis use were assessed over the two-week period via signal contingent (six random prompts per day), interval contingent (each bedtime), and event contingent (cannabis use episodes) assessments. RESULTS: Consistent with negative reinforcement models, participants with clinically significant Cluster D symptoms with elevated state anxiety had a greater likelihood of subsequent cannabis use and cannabis use resulted in less subsequent anxiety. The negative reinforcement hypothesis was only partially supported for those with Cluster B and C symptoms. CONCLUSIONS: The results suggest that negative reinforcement models may be especially relevant to understanding cannabis use among those with clinically elevated Cluster D symptoms.