A new study has raised questions around cannabis’ effects on cardiovascular health in young people. Published in the Canadian Medical Association Journal, the investigation is based around Centers for Disease Control and Prevention-collected data regarding 33,000 adults between the ages of 18 and 44.
It found that the rate of heart attacks rose over 50 percent among people who said they had used cannabis over the past 30 days. Study participants who had consumed cannabis more than four times a month saw a 230 percent increase in heart attack risk.
“We found an association between recent cannabis use and myocardial infarction, which persisted across an array of robust sensitivity analyses,” said one of the study’s authors Karim Ladha, a Unity Health Toronto clinician scientist, in a press statement.
"With all of the changes regarding the legalization of cannabis throughout the United States and Canada, there is a lot of assumption that cannabis has been around for thousands of years, this is a safe plant, a safe drug," Ladha told US News. "But the reality is the cannabis that exists today is very different from what people were using even two decades ago.”
But not everyone is swayed by this data — and the reality is that these findings are not a final statement on cannabis and heart health. There's actually a lot of data showing that weed can actually benefit heart health. For instance, one study shows that cannabis users actually have a greater chance of surviving heart attacks than those who do not consume. Another early study found that patients with hypertension saw a decrease in blood pressure after inhaling marijuana. Research on mice in 2013 determined that the activation of the CB1 receptor could offer protection from chronic heart failure. And while a study in 2012 found that inhaling cannabis might exacerbate some cardiovascular symptoms, marijuana consumed in other ways reduced the progression of atherosclerosis in mice.
So, take these new findings with a grain of salt.
"Let's keep in mind the fact that it's very easy to double a number if it's very small in the first place,” said Mitch Earleywine, a State University of New York at Albany professor of psychology and NORML advisory board member, told US News.
The study’s authors ultimately concluded that more research is necessary to clarify the connection between cannabis and heart health.
While the analysis did adjust for such factors, it should be noted that the cannabis consumers in the study were largely male cigarette smokers, who used e-cigarettes and were heavy drinkers.
Information published by Harvard Medical School suggests that this is not the first time that cannabis has been linked to heart trouble. In a primer published by the school’s website, the drug is tied to “raising resting heart rate, dilating blood vessels, and making the heart pump harder,” citing research that points to heart attack risk rising in the hour immediately after smoking weed.
The latter point was echoed by a specialist interviewed by Healthline regarding the study.
“With cannabis, especially THC, we see an increase in heart rate as well as blood pressure, both of which can be quite fast, which can precipitate a heart attack,” said Monty Ghosh, of the University of Alberta in Canada’s department of general internal medicine and neurology. “This is especially true after the first hour of use.”
Ghosh added that “the vast majority” of study participants who had gone through heart attacks consumed their cannabis through smokable forms.
The study was funded in part by the University of Toronto’s department of anesthesiology and pain medicine, though the study’s summary at does state that funders had no role in the “design, analysis, interpretation, preparation, review or approval of the manuscript.”
"I do hope these data might inspire everyone to improve their diets, exercise more regularly, and take a few moments each day to decrease their stress," said Earleywine. "But I fear these results will be misinterpreted as some sort of rationale to return to prohibition."