Medical cannabis users in Illinois opioid alternative program had similar psychological well-being as non-users | Research

The takeaway

Among 860 participants in Illinois' Opioid Alternative Pilot Program, there was no significant difference in psychological well-being between those who used medical cannabis and those who did not, with both groups averaging "good" well-being.

People considering medical cannabis as an opioid alternative, and policymakers evaluating opioid substitution programs.

No significant difference in psychological well-being between cannabis users and non-users (p=0.18)

What the researchers found

Average psychological well-being was 3.18 out of 5 (good) across the full sample. Cannabis users scored 3.21 and non-users 3.12, a non-significant difference (p=0.18). Regular cannabis use (3+ times per week) also showed no significant association with psychological well-being.

Why it matters

As states create opioid alternative programs that include cannabis, understanding psychological impacts is essential. This null finding is reassuring: substituting cannabis for opioids in this program did not appear to worsen psychological well-being, though it did not clearly improve it either.

The numbers in context

860 participants. Average age 47, 60% male, 67% of cannabis users had a disability. Well-being scores: users 3.21, non-users 3.12, p=0.18. No significant difference in sensitivity analysis of regular users vs non-users.

How the study worked

Survey sent from February-July 2019 to enrollees in Illinois' Opioid Alternative Pilot Program. Cannabis users (n=626) were compared with non-users (n=234) on psychological well-being (1-5 scale). Backward stepwise regression models were used, with sensitivity analysis for regular use.

What this study cannot tell us

Cross-sectional design cannot determine causation or change over time. Self-selection into cannabis use introduces bias. A single well-being measure (1-5 scale) may lack sensitivity. No baseline pre-program data available. Non-users in an opioid alternative program may have distinct characteristics.

How to read the evidence

Cross-sectional survey with no baseline measurement, limited by single well-being measure and self-selection bias.

When this study was published

Published in 2025, using 2019 survey data.

The bigger picture

The lack of difference could mean several things: cannabis neither helped nor harmed psychological well-being, the effects balanced out, or the measurement was not sensitive enough to detect differences. Given that 67% of cannabis users reported having a disability, the comparable well-being scores could also indicate that cannabis was helping to equalize well-being despite greater health burdens.

Questions still open

Would a longitudinal design show changes in well-being after starting medical cannabis? Does cannabis improve some aspects of well-being (pain relief) while worsening others (cognitive effects), resulting in a net neutral? Would more granular psychological measures reveal differences?

Common questions

Did medical cannabis improve mental health in this program?

It did not significantly improve or worsen psychological well-being compared to non-users in the same program. Both groups averaged "good" well-being on a 1-5 scale.

What is the Opioid Alternative Pilot Program?

An Illinois program that allows individuals to access medical cannabis as a direct substitute for opioids, aiming to reduce opioid dependence while managing pain and other qualifying conditions.

Read the original research

Medical Cannabis and Psychological Well-Being in Illinois' Opioid Alternative Pilot Program.

American journal of preventive medicine, 69(3), 107941

View on PubMed ↗Publisher’s paper ↗

Citation

Dubois, Cerina; Bobitt, Julie; Ding, Lei; Eurich, Dean T; Knapp, Ashley A; Jordan, Neil. (2025). Medical Cannabis and Psychological Well-Being in Illinois' Opioid Alternative Pilot Program.. American journal of preventive medicine, 69(3), 107941. https://doi.org/10.1016/j.amepre.2025.107941