Research Snapshot: What is the relationship between cannabis use and alcohol use for people living with HIV?

What you need to know:

This is the first study of people living with HIV in Ontario that looks at the link between cannabis use and alcohol use over time. Increases in recreational cannabis use were associated with increases in alcohol use, while increases in medicinal cannabis use were not. The findings are relevant as heavy drinking has negative outcomes for people with HIV.


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What is this research about?

More than half of people living with HIV report having tried cannabis in their lifetime. While studies have reported the potential benefits of cannabis use for symptom management, cannabis use is also associated with health risks such as risky sexual behaviours, cannabis dependence, and increased risk of using other substances, such as alcohol. Heavy drinking in turn is associated with negative health outcomes, such as poor adherence to HIV/AIDS treatment, risky sexual behaviours, and increased mortality.

This study looked at the association between cannabis use and alcohol use among people living with HIV, and specifically what kind of impact medicinal cannabis use (e.g., for pain, appetite, nausea) and recreational cannabis use had on alcohol use.

What did the researchers do?

The study used data from participants who enrolled in the Ontario HIV Treatment Network Cohort Study between October 2007 and January 2015. Participants completed questionnaires on alcohol and cannabis use at enrollment and at annual follow-ups.

The analysis included 763 participants who reported using cannabis once during the study. The majority of participants identified as white, male, and gay. On average, participants completed follow-ups yearly for 3.5 years.

The analysis looked at whether changes in the frequency of cannabis use for recreational or medicinal reasons predicted changes in alcohol use both on average and for individual participants.

What did the researchers find?

There were significant differences between medicinal and recreational cannabis use:

  • Those who used cannabis recreationally reported less frequent cannabis use compared to those who used cannabis medicinally.
  • Those who used cannabis recreationally said they consumed more alcohol than those who used it medicinally.

When looking at the changes over time for individual participants, the researchers found:

  • higher recreational cannabis use was linked to heavier drinking
  • changes in medicinal cannabis use were not associated with changes in drinking.

The effects were the same for men and women and did not differ according to age, race, or sexual orientation.

Limitations and next steps

It's important for healthcare providers to know that the size of the effect was small. The increase in cannabis use was associated with a small increase in the risk of screening positive for problematic drinking. In addition, the researchers cannot draw conclusions about the cause of the changes.

It's unclear whether recreational cannabis use caused the increase in alcohol use, or if it's the other way around. Also, the study was not designed to determine whether the shift from recreational to medicinal cannabis use was associated with changes in alcohol use.

The mechanisms that explain the link between cannabis use and alcohol were not directly evaluated. However, the researchers theorized the findings may be linked to where recreational and medicinal cannabis are used. People who use cannabis recreationally may use it in similar settings with alcohol (e.g. at a party) and changes in their behaviours may affect the use of both. People who use cannabis medicinally may frequently use it to treat symptoms, which may be independent from their alcohol use. The next step will be to investigate these possible explanations.

How can you use this research?

In light of cannabis legalization in Canada, it's important to understand the link between cannabis and alcohol use in different clients and populations, and to be aware that different reasons for use (medicinal vs. recreational) may have different outcomes within the same population.

As heavy drinking is associated with negative health risks for people living with HIV, it's important for health care providers and policymakers to be aware of how changes in cannabis use are linked to changes in alcohol use, given the high rates of cannabis use among these individuals.

About the researchers

Jeffrey D. Wardell,1, 2 Paul A. Shuper,1,3 Christian S. Hendershot.1,2,4,5
1.Institute for Mental Health Policy Research,Centre for Addiction and Mental Health,Toronto, Canada
2.Department of Psychiatry, University ofToronto, Toronto, Canada
3.Dalla Lana School of Public Health, Universityof Toronto, Toronto, Canada
4.Campbell Family Mental Health ResearchInstitute, Centre for Addiction and MentalHealth, Toronto, Canada
5.Department of Psychology, University ofToronto, Toronto, CanadaKeywords Cannabis, Medical cannabis, Recreational Cannabis use, Alcohol, AUDIT-C, Co-use, HIV, AIDS.

This Research Snapshot was written by Andra Ragusila based on the article, “A longitudinal investigation of the association between cannabis use and alcohol use among people living with HIV,” published in the Drug and Alcohol Dependence Journal in 2018. 

This research was funded by the AIDS Bureau, Ontario Ministry of Health and Long-term Care. The researchers wish to acknowledge the contributions of the Ontario HIV Treatment Network (OHTN) Cohort Study team. The opinions, results and conclusions are those of the authors only. No endorsement by OHTN is intended or should be inferred.

This Research Snapshot was developed by Evidence Exchange Network, part of the Provincial System Support Program at CAMH, with support from Health Canada. The views expressed herein do not necessarily represent the views of Health Canada.