Cannabis Use Stays Stable During Methadone Treatment and May Reflect Self-Medication | Research

The takeaway

Cannabis use patterns did not change during the first year of methadone maintenance treatment, suggesting that cannabis use reflects pre-existing vulnerability or self-medication rather than a coping response to methadone itself.

Read this if you are in methadone treatment and use cannabis, or work with patients in opioid treatment programs.

Cannabis use showed no significant change during 12 months of methadone treatment

What the researchers found

Researchers followed 188 opioid-dependent individuals starting methadone maintenance treatment for 12 months, tracking cannabis use at enrollment, 3, 6, and 12 months.

Cannabis use levels showed no significant variation throughout treatment. The factors associated with cannabis use were the same before and after starting methadone, suggesting that treatment itself did not change cannabis use patterns.

Ongoing opioid use was associated with both non-daily cannabis use (OR = 3.11) and daily cannabis use (OR = 2.58). The number of health problems reported was specifically associated with daily cannabis use (OR = 1.12 per additional problem), supporting a self-medication hypothesis.

Why it matters

A common concern is that methadone treatment might drive patients to use cannabis as a substitute or coping mechanism. This study found no evidence for that, instead suggesting cannabis use reflects broader substance use vulnerability and health-related self-medication.

The numbers in context

188 participants; 12-month follow-up; no significant variation in cannabis use (p=0.85); opioid use OR=3.11 (non-daily) and 2.58 (daily cannabis use); health problems OR=1.12 per problem for daily use

How the study worked

Prospective cohort study following 188 opioid-dependent individuals initiating methadone maintenance for 12 months. Cannabis use measured at baseline and months 3, 6, and 12. Analyzed using mixed multinomial logistic regression to account for repeated measures.

What this study cannot tell us

Observational design cannot prove causation. Self-reported cannabis use may be underestimated. Twelve-month follow-up may be too short to capture longer-term patterns. French healthcare context may not generalize globally.

How to read the evidence

Prospective longitudinal design with repeated measures, but observational and limited to one French treatment network.

When this study was published

Published in 2015. Research on cannabis-opioid interactions in addiction treatment has continued to evolve.

The bigger picture

The relationship between the cannabinoid and opioid systems suggests potential for cannabinoid-based pharmacotherapies in addiction treatment. Understanding that cannabis use during methadone treatment is not driven by methadone itself could inform more nuanced clinical approaches.

Questions still open

Should cannabis use during methadone treatment be actively treated or tolerated? Could cannabinoid-based therapies enhance methadone treatment outcomes? Does cannabis use affect methadone treatment retention or opioid abstinence rates?

Common questions

Does methadone treatment cause people to use more cannabis?

This study found no evidence of that. Cannabis use patterns remained stable throughout 12 months of methadone treatment, and the factors associated with cannabis use were the same before and during treatment.

Why do people on methadone use cannabis?

The data suggested two main drivers: a shared vulnerability to substance use in general (evidenced by the association with ongoing opioid use) and self-medication for health problems (daily cannabis use correlated with more reported health issues).

Read the original research

Variations in Cannabis Use Level and Correlates in Opiate-Users on Methadone Maintenance Treatment: A French Prospective Study.

Journal of substance abuse treatment, 58, 100-5

View on PubMed ↗Publisher’s paper ↗

Citation

Mayet, Aurélie; Lions, Caroline; Roux, Perrine; Mora, Marion; Maradan, Gwenaelle; Morel, Alain; Michel, Laurent; Marimoutou, Catherine; Carrieri, Maria Patrizia. (2015). Variations in Cannabis Use Level and Correlates in Opiate-Users on Methadone Maintenance Treatment: A French Prospective Study.. Journal of substance abuse treatment, 58, 100-5. https://doi.org/10.1016/j.jsat.2015.06.015