The effects of cannabis use expectancies on self-initiated cannabis cessation.

Abstract

To prospectively investigate the relation between cannabis use expectancies and cannabis use prior to and during a self-initiated cannabis cessation attempt. Cohort design that followed participants for 4 weeks following a self-initiated cessation attempt. United States Department of Veterans Affairs medical center. One hundred cannabis dependent military veterans. The Marijuana Effects Expectancy Questionnaire at baseline; the timeline follow-back procedure at baseline and during the cessation attempt. Cannabis use at baseline was associated with positive (P = 0.01), but not negative (P = 0.25), expectancies. Cannabis lapse was associated with positive (P = 0.03) and negative expectancies (P = 0.01), and relapse was associated with positive (P = 0.04), but not negative (P = 0.21), expectancies. The trajectory of average cannabis use during the cessation period was associated with positive (P = 0.03), but not negative (P = 0.96), expectancies. Results were similar in effect and statistical significance when adjusting for demographic factors, motivation to quit cannabis, mental disorder diagnoses, and alcohol and tobacco use, and when analyzing complete data sets obtained through multiple imputation. In the USA, cannabis use expectancies, especially those regarding the positive effects of cannabis use, appear to be strongly and consistently linked to cannabis use and quit failure.