Frequent cannabis (marijuana) use among young people was linked to an increased risk of stroke according to a study presented at the American Heart Association's Scientific Sessions 2019 and published in Stroke, a Journal of the American Stroke Association, a division of the American Heart Association.

"As cannabis products become increasingly used, getting clearer, scientifically rigorous data is going to be important as we try to understand the overall health effects of cannabis," said Robert Harrington, M.D., president of the American Heart Association and the Arthur L. Bloomfield professor of medicine and chairman of the department of medicine at Stanford University in Stanford, California.

Young people who used cannabis frequently and also smoked cigarettes or used e-cigarettes were three times more likely to have a stroke compared to non-users.

The study also showed that cannabis users who did not use tobacco products but reported using cannabis for more than 10 days a month were nearly 2.5 times more likely to have a stroke compared to non-users.

The cannabis users were also more likely to be heavy drinkers, current cigarette users and e-cigarette users, which may have also influenced their risk, even though the researchers adjusted for those factors in their analysis.

Participants in the study included more than 43,000 adults aged 18 to 44, of whom nearly 14% reported using cannabis in the last 30 days. Compared with non-users, marijuana users were often younger, non-Hispanic white or black, were less likely to be college graduates and were often physically active.

"Young cannabis users, especially those who use tobacco and have other risk factors for strokes, such as high blood pressure, should understand that they may be raising their risk of having a stroke at a young age," said lead study author Tarang Parekh, M.B.B.S., M.S., a health policy researcher at George Mason University in Fairfax, Virginia. "Physicians should ask patients if they use cannabis and counsel them about its potential stroke risk as part of regular doctor visits."

The study was observational and did not examine the biological mechanism connection between stroke and cannabis use, so it identified a potential link, rather than proving cause and effect. The data analyzed was from the behavioral risk factor surveillance system (BRFSS) (2016-17), a nationally representative cross-sectional survey collected by the U.S. Centers for Disease Control and Prevention.

Co-authors are Sahithi Pemmasani, M.B.B.S., and Rupak Desai, M.B.B.S. Author disclosures are in the abstract and manuscript. This study did not receive outside funding.