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Yes, recent US study found link between marijuana use and risk of stroke

The headline of an article widely shared on Facebook, including in South Africa, says that a new study shows “heavy weed use [is] linked to a higher risk of stroke in young people”.

A stroke is “when the blood supply to part of your brain is interrupted or reduced, preventing brain tissue from getting oxygen and nutrients”, according to the Mayo Clinic. It’s a medical emergency and is the second largest cause of death worldwide, say annual burden of diseases reports. 

The article linking marijuana or “weed” use and strokes has been flagged as possibly false by Facebook’s fact-checking system. Is it accurate?



Article accurately reports results of 2019 study


The article, from 12 November 2019, reports on an analysis published the day before, in the scientific journal Stroke. The journal is published in the US by the American Heart Association, which supports scientific research in the “fight against heart disease and stroke”. 

The article says that the study “looked at 43,000 adults ages 18 to 44 who had used marijuana within the last 30 days” and found “significantly higher odds of stroke” in “young” weed smokers, compared to nonusers. 

And this is correct. The study concluded that there “may be a significantly higher odds of stroke in young marijuana users (18–44 years) as compared with nonusers with even greater odds among frequent users”. “Frequent users” report smoking weed ten days a month or more. 

Study based on US data


The Stroke study analysed “pooled data from the Behavioral Risk Factor Surveillance System”. This is a “system of health-related telephone surveys that collect state data about US residents”, run by the Centers for Disease Control and Prevention, or CDC. The analysis was of data on people living in the US. 

The study authors said that more research was needed on the effects of marijuana or cannabis use because of its “rising popularity” among young people. They linked this to recent “legalisation and decriminalisation of marijuana/cannabis use in the United States”. 

Since 2012, 11 US states have legalised marijuana use, and the use of the drug is decriminalised in many other states. In Africa, Lesotho and Zimbabwe have relaxed the laws about growing marijuana. In South Africa the private use of weed has been decriminalised since 2018. 

Study author confirmed findings


The article shared on Facebook also interviewed Tarang Parekh, the lead author of the study. He is a researcher at the College of Health and Human Services at George Mason University in the state of Virginia in the US. 

Parekh summarised the study’s findings: “Marijuana may not be as harmful as other illegal substances like cocaine or meth, but its frequent consumption with other substances critically increases the risk of stroke at a younger age.” – Africa Check




 

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