Research about whether smoking cannabis increases your chances of suffering a stroke has been contradictory over the years. The latest study, published last week, found no association between the most common type of stroke and recent cannabis use.
The study, published in Neurology, the journal of the American Academy of Neurology, was compiled by looking at urine drug screening from patients admitted to the University of Mississippi Medical Center between 2015-2017. Out of a total of 9,350 patients, 1,643 tested positive for cannabis. Of these, the incidence of ischemic stroke — a stroke caused by a blockage in a blood vessel, such as a blood clot — was 7.91%, just over half the percentage among non-smokers (15.66%).
“We have found that recent cannabis use is not associated with incidence of [ischemic stroke],” the researchers wrote, though they did note that their findings differed from previous studies. One explanation for those differences could be that the current study’s researchers did not have access to data about whether the subjects use cannabis chronically, how frequently, or in what dosage. They were also not able to include other risk factors such as body mass index or physical inactivity.
The researchers mention a 2016 study that found markedly different results. According to that study’s findings, “heavy cannabis users in the general community have a higher rate of non-fatal stroke or transient ischemic attack than non-cannabis users.”
The earlier study found that people who used cannabis in the past year had 3.3 times the rate of stroke or transient ischemic attack, and the elevated risk “was specific to participants who used cannabis weekly or more often.”
In the study published by Neurology last week, the researchers did not take into account the frequency of cannabis use or dosage.
The findings of the study also differ strongly from those of a November, 2019 report that found that “there may be significantly higher odds of stroke in young marijuana users (18-44) as compared with non-users, with even greater odds among frequent users” who use it more than 10 times a month.
The 2019 study found that young adults who had recently used marijuana had 1.82-times higher odds of stroke compared with non-users, and that this increased to 2.45-times more likely with frequent marijuana users.
The study was compiled using the publicly available Behavioral Risk Factor Surveillance System datasets from 2016-2017.