Examination of Fear Extinction in Chronic Cannabis Use, Anxiety Disorders, and their Co-occurrence

Abstract

Comorbid cannabis use and anxiety are common, but the relationship is not well understood. The main active ingredient of cannabis is Δ9-tetrahydrocannabinol (Δ9-THC). Acute THC intoxication has been shown to improve between and within-session fear extinction, while chronic THC intoxication impairs fear extinction and discrimination. The current project aimed to determine if chronic cannabis use was associated with worse fear discrimination, extinction (within-session extinction), and extinction retention (between-session extinction) in the anxiety disorder population. 46 participants from three groups (i.e. clinically significant anxiety and cannabis-naïve, chronic cannabis users, or cannabis-naïve healthy controls) completed a 2-day fear differential conditioning paradigm. Results suggest that chronic cannabis-users have an impaired ability to extinguish within-session fear-based responding as compared to the other two groups. There was no evidence of significant group differences in extinction retention or fear discrimination. Findings have important clinical implications as they suggest that chronic cannabis use may impair one’s ability to extinguish fear-based learning, a primary mechanism of exposure-based therapy, which may be a potential barrier to therapy effectiveness.