Cannabis use increases risk of heart attacks in young adults

Cannabis is a commonly used recreational drug that has become legalized and decriminalized in Canada and parts of the US in recent years. However, despite its increasing availability and social acceptance, the effects of cannabis on cardiovascular health have not yet been established.

In new research published in the Canadian Medical Association Journal, researchers used national health survey data to assess the prevalence of recent cannabis use in young adults (aged 18 to 44) in the US, and its relationship with occurrence of heart attacks (myocardial infarction). Young adults of this age group are not usually considered to be at risk of having a heart attack, and this allowed the researchers to consider the effects of cannabis use in particular.

Survey data from 33,000 young adults was included in this study. The data were derived from a survey conducted by the US Centers for Disease Control and Prevention during 2017 and 2018. In the survey, 17 percent of young adults reported recent use of cannabis (within the past 30 days) and among these users, 1.3 percent also reported having a heart attack. By comparison, the incidence of a heart attack was only 0.8 percent among non-users. This represents an increased risk to cannabis users of more than one and a half times.

Although the method of consumption made no difference to this relationship, the researchers found that the effect was stronger in those people who used cannabis more frequently. These results support the findings of earlier studies conducted in hospitals that established a link between heavy cannabis use and heart attack incidence. 

“With recent legalization and decriminalization, cannabis use is increasing in young adults in North America, and we do not fully know its effects on cardiovascular health,” says Dr. Karim Ladha, a clinician scientist at Unity Health Toronto. “We found an association between recent cannabis use and myocardial infarction, which persisted across an array of robust sensitivity analyses. Additionally, this association was consistent across different forms of cannabis consumption, including smoking, vaporization, and other methods such as edibles. This suggests that no method of consumption is safer than another in this regard.”  

The researchers found that cannabis users tended to be male, smoke cigarettes or e-cigarettes (vape) and to have a high alcohol intake; these factors may have contributed to the risk of heart attack but were adjusted for in the analysis conducted in this study. It is also noteworthy that, although the study provides evidence of a link between cannabis use and heart attack, the biological mechanisms by which these two variables are related is not known.

“We analyzed the Behavioral Risk Factor Surveillance System data set (2017–2018) because it is the best available source for providing insights which are generalizable and nationally representative,” says Nikhil Mistry, a PhD candidate at the University of Toronto. “As a young adult, it is important to be aware of the risks associated with cannabis use, especially in the current climate where we are exposed to a wealth of misinformation and non–evidence-based health recommendations.” 

Dr. David Mazer, a clinician scientist at Unity Health Toronto, adds, “Not only young adults, but physicians and other clinicians need to be aware of this potentially important relationship. Cannabis use should be considered in cardiovascular risk assessment. When making decisions about cannabis consumption, patients and physicians should consider its associated benefits and risks, in the context of their own health risk factors and behaviors.”  

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By Alison Bosman, Earth.com Staff Writer