Study finds occasional marijuana use raises stroke risk by 40%

Researchers analyzing data from more than 440,000 U.S. adults say occasional marijuana use is linked to a 40 percent higher odds of reporting a prior stroke, according to a study highlighted by ScienceDaily on Tuesday. The analysis, which relied on self‑reported cannabis consumption and medical history, found the association even among people who used the drug less than once a month.

The finding arrives as cannabis use surges nationwide following a wave of legalisation at state level. In 2023, an estimated 48 million Americans reported using marijuana in the past year, up from 35 million a decade ago. Health officials have long debated whether the plant’s psychoactive compounds affect the heart and blood vessels, with earlier studies offering mixed results. Some research suggested a temporary rise in heart rate and blood pressure after smoking, while other work found no clear link to long‑term cardiovascular disease. The new study adds weight to concerns that even infrequent exposure may have measurable risks.

The investigators used data from the National Health and Nutrition Examination Survey, matching participants’ answers about cannabis frequency with their reports of stroke or transient ischemic attack. After adjusting for age, sex, smoking, hypertension, diabetes and other risk factors, occasional users showed a 1.4‑fold increase in the odds of a stroke compared with non‑users. Frequent users—those who reported daily or near‑daily use—had an even larger, though not statistically distinct, elevation. Lead author Dr. Emily Chen of the University of Michigan cautioned that the study cannot prove causation, noting that unmeasured lifestyle factors could contribute. Nonetheless, the authors argue that the association merits attention from clinicians who may not routinely ask patients about marijuana use.

Public‑health experts say the results underscore the need for prospective, longitudinal studies that can track cannabis exposure and cardiovascular events over time. In the meantime, physicians are urged to incorporate cannabis use into routine risk assessments and to counsel patients on potential harms, especially those with existing heart‑related conditions. Regulators may also consider adding cardiovascular warnings to product labels as more evidence emerges about the drug’s systemic effects.