Believing Cannabis Has Positive Effects Predicted Failure to Quit in Veterans | Research

The takeaway

Positive expectations about cannabis effects, such as believing it relieves tension or enhances social experiences, consistently predicted cannabis use, lapse, and relapse during a 4-week quit attempt among 100 veterans.

Read this if you are trying to quit cannabis and find yourself thinking about the positive effects you are missing.

Positive expectancies predicted lapse, relapse, and use trajectory during quit attempts

What the researchers found

One hundred cannabis-dependent military veterans were followed during a self-initiated 4-week quit attempt. Positive cannabis expectancies (believing cannabis produces desirable effects) predicted multiple outcomes: higher baseline use, lapsing during the attempt, relapsing fully, and the overall trajectory of use during cessation.

Negative expectancies (believing cannabis has bad effects) played a limited role, predicting only initial lapse but not sustained use or relapse. Results held after adjusting for demographics, motivation to quit, mental health diagnoses, and alcohol and tobacco use.

Why it matters

Understanding what predicts quit failure helps design better interventions. If positive expectancies, specific beliefs about cannabis benefits, drive continued use, then therapeutically challenging these beliefs could improve outcomes. Simply knowing cannabis is harmful (negative expectancies) was not enough to prevent relapse.

The numbers in context

100 veterans followed 4 weeks. Positive expectancies predicted: baseline use (p=0.01), lapse (p=0.03), relapse (p=0.04), use trajectory (p=0.03). Negative expectancies predicted only lapse (p=0.01). Results robust after covariate adjustment.

How the study worked

Cohort design following 100 cannabis-dependent military veterans for 4 weeks after a self-initiated quit attempt. Cannabis use expectancies measured at baseline with the Marijuana Effects Expectancy Questionnaire. Cannabis use tracked with Timeline Followback at baseline and during cessation. Analyses adjusted for multiple covariates.

What this study cannot tell us

Self-guided quit attempts may not represent structured treatment settings. Military veterans may not be representative of all cannabis users. Four-week follow-up is relatively short. Expectancies were measured at baseline and may change during the quit attempt. Self-report measures for both expectancies and use.

How to read the evidence

Prospective cohort study with multiple outcome measures and appropriate controls; moderate evidence.

When this study was published

Published in 2013. Expectancy-based interventions for substance use have continued to develop.

The bigger picture

This finding parallels alcohol research showing that positive outcome expectancies are stronger predictors of drinking behavior than negative ones. It suggests that cannabis cessation interventions should focus more on challenging positive beliefs about cannabis than on emphasizing negative consequences.

Questions still open

Would cognitive restructuring of positive cannabis expectancies improve quit rates? Do expectancies change during treatment, and does that change predict outcomes? Are positive expectancies about specific effects (tension relief, social enhancement) differentially predictive?

Common questions

Why do positive beliefs about cannabis matter more than knowing it is harmful?

People are generally more motivated by anticipated rewards than by anticipated costs. A veteran who believes cannabis helps with relaxation, sleep, or social connection has a strong pull toward use, even if they also know it has negative consequences. Addressing these positive beliefs directly may be more effective than emphasizing risks.

What are cannabis use expectancies?

Expectancies are beliefs about what cannabis will do for you. Positive expectancies include things like "cannabis helps me relax," "cannabis makes socializing easier," or "cannabis enhances pleasure." Negative expectancies include beliefs that cannabis impairs performance or causes health problems. This study found positive expectancies were stronger predictors of continued use.

Read the original research

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

Addiction (Abingdon, England), 108(9), 1649-57

View on PubMed ↗Publisher’s paper ↗

Citation

Boden, Matthew Tyler; McKay, James R; Long, W Robert; Bonn-Miller, Marcel O. (2013). The effects of cannabis use expectancies on self-initiated cannabis cessation.. Addiction (Abingdon, England), 108(9), 1649-57. https://doi.org/10.1111/add.12233