Cannabis expectancies and associations with cannabis use and health functioning among adults with chronic pain.

Introduction: Cannabis is increasingly available to individuals in the United States, with the majority of states legalizing medical or recreational cannabis use. Cannabis expectancies (e.g., positive expectations from cannabis use) are related to more frequent cannabis use and associated with greater odds of lapse following a cessation attempt.

Methods: To evaluate the relationship between expectancies and cannabis- and health-related outcomes, we surveyed adults who used medical cannabis for chronic pain (n = 633; 52.2 % female; 82.1 % white) over a two-year period. Then, we performed a principal components analysis (PCA) on the Cannabis Expectancies Questionnaire to derive components of cannabis expectancies. We performed k-means clustering to identify subgroups with similar expectancies. The relationship between subgroup assignment and cannabis use outcomes (frequency, quantity), and physical and mental health functioning were evaluated.

Results: The PCA identified a three-component solution and k-means clustering identified four subgroups: low expectancies, negative expectancies, amotivation expectancies, and positive expectancies. Participants' cannabis expectancies were dynamic over time. After adjusting for demographics, expectancy subgroup was able to predict six-month cannabis use frequency (χ2(3) = 11.244; p = 0.010) and mental health functioning (χ2(3) = 24.926; p < 0.001), but not quantity (χ2(3) = 2.741, p = 0.433) or physical health functioning (χ2(3) = 5.110, p = 0.164).

Conclusion: In a large cohort of individuals who use medical cannabis, four subgroups with differing cannabis expectancies emerged: low expectancies, negative expectancies, amotivation expectancies, and positive expectancies. These subgroups predicted subsequent outcomes and may be important for targeted intervention approaches to reduce cannabis use and improve functioning.