Investigating the Relationship Between Cannabis Expectancies and Anxiety, Depression, and Pain Responses After Acute Flower and Edible Cannabis Use.

Objective: Cannabis has been touted for a host of pharmacological and therapeutic effects and users commonly report reduced symptoms of physical and mental health conditions, including anxiety, depression, and chronic pain. While there is existing empirical evidence supporting these effects of cannabis use, little is known about the extent to which these effects result from pharmacological versus expectancy factors. We evaluated the associations between participants' cannabis expectancies and their acute self-reported reactions after using legal market forms of cannabis with varying levels of cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC) in three domains: anxiety, depression, and pain.

Methods: Fifty-five flower and 101 edible cannabis users were randomly assigned and asked to purchase at a local dispensary one of three products containing varying levels of CBD and THC. Participants completed a baseline assessment where they reported expectancies about general health effects of cannabis use and an experimental mobile laboratory assessment where they administered their assigned products. Edible users also reported their domain-specific expectancies about cannabis use in improving anxiety, depression, and pain. Following administration, participants completed acute indicators of anxiety, depression, and pain operationalized through subjective acute tension, elation, and a single-item measure of pain.

Results: Among flower users, more positive expectancies for cannabis to improve general health were correlated with greater reductions in tension at acute post-use. This finding was replicated among edible users. Unlike flower users, more positive expectancies for cannabis to improve general health were also correlated with greater increases in elation and greater reductions in pain among edible users. More positive expectancies for cannabis to improve depression and pain were also correlated with greater increases in elation and greater reductions in pain, respectively, among edible users.

Conclusions: Cannabis users' expectancies significantly impacted some of the acute subjective effects of legal market cannabis products. Among both flower and edible users, consistent, significant expectancy effects were found. Results were consistent with prior findings and demonstrate the need to measure and control pre-existing expectancies in future research that involves cannabis administration. Clinical trial registration number: NCT03522103.