Study links cannabis use to greater heart disease and stroke risk

More than 40 years after medical marijuana was legalized in California, cannabis has become a widely used way for Americans to unwind or ease nausea and pain.

But new research suggests that this common habit may carry an overlooked downside, with use tied to a higher risk of cardiovascular problems.

The study found that even occasional cannabis use, including marijuana, was associated with a greater risk of cardiovascular disease, with an even stronger connection to stroke.

That finding matters as cannabis use has climbed to record levels in the U.S., with as many as one in four adults reporting use over the past year.

“As cannabis use becomes more common, it is increasingly important that people and their healthcare professionals include it in conversations about cardiovascular health, just as they discuss tobacco, alcohol and other commonly used substances,” said study author and heart surgeon Aabha Divya.

Cannabis and heart risks

Researchers analyzed data from nearly half a million Americans through the CDC’s Behavioral Risk Factor Surveillance System.

Participants across the country were asked by phone survey how often they had used cannabis, including marijuana, through smoking, vaping or edibles over the previous month.

Cannabis is the broader plant, while marijuana refers to parts of the plant that contain psychoactive THC. Products such as non-psychoactive CBD and hemp also come from cannabis, but not marijuana.

Respondents were also asked whether they had ever been diagnosed with a heart attack, heart disease, heart-related chest pain or a stroke.

The researchers found that people who used cannabis occasionally, defined as one to five days in the past month, had a 23% higher likelihood of reporting a history of cardiovascular disease than nonusers.

Notably, the odds of cardiovascular disease did not rise steadily with heavier marijuana use. The team also did not find a significant link between cannabis use frequency and heart attack.

“We were surprised to find that the link between cannabis use and cardiovascular disease was not straightforward,” Divya said.

“We expected that the chances of heart disease would gradually rise as people used cannabis more often, but that wasn’t the case. Both low-use and heavy-use groups had higher odds of developing heart disease.”

Cannabis and stroke

Cardiovascular disease is an umbrella term for disorders affecting the heart and blood vessels. Within that group, stroke showed the strongest association with cannabis use.

A stroke occurs when blood flow to the brain is interrupted or blocked, often because of fatty plaque buildup in blood vessels or when a vessel leaks or ruptures.

Stroke is the fourth leading cause of death and a major cause of disability in the U.S.

The study found that low-frequency use, or one to five days in the past month, was linked to a 40% higher chance of stroke. Heavy use, defined as 16 days to daily use in the past month, was associated with a 25% higher risk of stroke.

Cannabis is not an ‘innocent bystander’

The associations were seen even after accounting for factors including tobacco smoking, alcohol use, obesity, diabetes, chronic kidney disease, physical inactivity, education and income.

“Many patients who use cannabis may also smoke tobacco … Cannabis has always been considered an innocent bystander; however, this is not the case,” said Robert L. Page II, chair of the writing group for the American Heart Association’s 2020 cannabis scientific statement.

“Overall, cannabis is beginning to emerge as a major contributor to premature heart disease in young and older adults, which can lead to serious cardiovascular events,” he said.

Still, the research does not prove that cannabis causes cardiovascular problems. It only captured associations at one point in time and relied on self-reported cannabis use and heart disease diagnoses.

The authors also noted they did not have information on the potency of the cannabis used by participants.