Cannabis Users at Higher Risk of Heart Attack and Stroke

A new, large-scale study linking cannabis consumption with increased risk of heart attacks and strokes has prompted Bay Area researchers to call for heightened clinical screening and regulation of the legal marijuana market.

The meta analysis (PDF), published Tuesday in the British Medical Journal’s Heart, compiled research results from 24 studies published over six years and found cannabis users face a 20% higher risk of stroke, 29% higher risk of heart attack, and double the risk of cardiovascular death.

“With legalization came a false perception that cannabis might be a safe, natural wellness product, and that if you take it for pain or for sleep, there’s no risk,” said Dr. Lynn Silver, a pediatrician and researcher at the nonprofit Public Health Institute in Oakland. “That’s just not the case.”

The researchers evaluated published studies that mostly excluded people who use tobacco, minimizing a common confounding factor in isolating cardiovascular risk of cannabis, but they were imprecise in measuring how people consumed cannabis and how often. While research suggests smoking pot may present more severe health problems than ingesting it, more studies are needed to clarify how to attribute risk.

The growing body of scientific evidence raises concerns and is enough to warrant more clinical screening for cannabis use among “patients presenting with serious cardiovascular disorders,” the study authors wrote.

Silver and Stanton Glantz, a retired UCSF professor and renowned tobacco researcher, went even further in an editorial published alongside the study (PDF), arguing that doctors should screen and educate all patients about the health risks, particularly in light of the fact that cannabis use among 35–50-year-olds — the age range when cardiovascular disease begins to develop — has tripled since 2008.

The rate of adults who use cannabis daily is now on par with those who drink alcohol or smoke cigarettes every day.

“Before we were seeing a wisp of smoke that there was cardiovascular risk,” Silver said. “That became a cloud of smoke. Now we’re starting to see signs of a wildfire of a more serious problem, with pretty consistent evidence emerging.”

Addressing cannabis consumption should not only become part of the medical framework for how clinicians prevent heart disease and stroke, Silver and Glantz wrote, but preventing heart disease and stroke should also be part of how states regulate cannabis markets. They called for health warning labels on cannabis products, restrictions on marketing, and limits on product potency.

“Today regulation is focused on establishing the legal market with woeful neglect of minimizing health risks,” they wrote.