Adults who used marijuana only a few days a month were more likely to report having had a stroke than those who hadn’t used it recently, according to a preliminary study of nearly 443,000 U.S. adults. The study found a link, but it couldn’t determine whether marijuana use came before the stroke or played a role in causing it.

Researchers at Tulane University School of Medicine analyzed responses to a federal health survey conducted from 2020 through 2024. Participants reported how many days they had used cannabis in the previous month and whether a health professional had ever told them they’d had a stroke or heart attack or had coronary heart disease.

Compared with adults who reported no recent cannabis use, those who used it one to five days in the previous month had 40% higher odds of reporting a past stroke. Those who used it 16 to 30 days had 25% higher odds. Both groups were also more likely to report a history of cardiovascular disease overall, though researchers found no statistically significant link between how often people used cannabis and a history of heart attack.

Lead researcher Aabha Divya said the team expected the association to grow stronger as cannabis use became more frequent. It didn’t. The larger figure for occasional users doesn’t establish that using marijuana occasionally is more dangerous than using it regularly. Researchers also reported a similar pattern across methods of use, including smoking, vaping and eating cannabis products. The survey didn’t track how much people consumed or how strong the products were.

One of the biggest limitations was timing. The survey asked about cannabis use in the past month but about strokes that could have happened years earlier. Some people may have started using cannabis after a stroke, while others may have quit after a cardiovascular diagnosis. The study also relied on people to accurately report their use and medical history.

The findings were scheduled for presentation at the American Heart Association’s Scientific Sessions in Chicago and have not been peer reviewed. Divya said the results give patients and clinicians another reason to discuss cannabis use when talking about heart and stroke risk, much as they already discuss tobacco and alcohol.