Cannabis use may predict opioid use in women undergoing addictions treatment, study says

A new study suggests that the use of cannabis may impact treatment in women undergoing methadone treatment therapy.

Researchers from McMaster University and St. Joseph's Healthcare Hamilton have found that women in methadone treatment who use cannabis are 82 per cent more likely to continue using opioids. This means that women who use cannabis are at high risk of failing methadone treatment.

"About 60 per cent of men and 44 per cent of women who are undergoing methadone treatment therapy also use cannabis," said the study's senior author, Dr. Zena Samaan. "Tailoring treatment to the patient's sex can help us to assess the patient's risk better and deliver more accurate, personalized treatment."

These findings could influence the way in which women diagnosed with opioid use disorder are treated.

Samaan is an associate professor of psychiatry and behavioural neurosciences at McMaster University and a clinician and researcher at St. Joseph's Healthcare Hamilton.

"As cannabis use seems to be a predictor for continuing opioid use despite treatment with methadone, clinicians should screen for cannabis and use these screening results to better plan treatment and resource allocation," said Samaan.

The research team recruited 777 participants from 16 Canadian Addiction Treatment Centre sites across Ontario.

The latest Canadian Tobacco, Alcohol and Drugs Survey taken in 2013 found that two per cent of Canadians reportedly abused opioids. The Canadian Centre on Substance Abuse reports that opioid-related deaths increased by over 240 per cent between 1990 and 2010.

The study was published online in Biology of Sex Differences and was funded by the Canadian Institutes of Health Research, the Chanchlani Research Centre and the Peter Boris Centre for Addictions Research.