Cannabis Exposure Was Associated With Higher Stroke Odds Even at Low Use Levels
New preliminary findings presented at the American Heart Association’s Scientific Sessions point to a cardiovascular signal that clinicians can no longer treat as peripheral: cannabis use was associated with higher odds of stroke in a large U.S. adult cohort, and the association appeared even among people who reported using marijuana only a handful of days per month. In a dataset of 442,906 adults, low-frequency users had 40% higher odds of reporting a history of stroke than nonusers, while heavy users had 25% higher odds.
The size of the cohort gives the analysis unusual reach. The pattern it produced is less orderly than many clinicians might expect. Risk did not climb in a neat dose-response line as marijuana use became more frequent, and that irregularity raises questions about biology, behavior, product potency, and the limits of self-reported exposure data.
A Population Survey Captured a Broad Spectrum of Use
The analysis drew on responses from the Behavioral Risk Factor Surveillance System, a telephone survey of U.S. adults collected from 2020 through 2024 in jurisdictions that included an optional marijuana module. The survey covered multiple routes of use, including smoking, vaping, and ingesting gummies or other cannabis-containing foods. Participants averaged 49 years of age, and approximately half were women.
Cannabis exposure was divided into four groups: no recent use, low-frequency use on 1 to 5 days in the prior month, moderate-frequency use on 6 to 15 days, and heavy use on 16 to 30 days. Participants also reported whether a clinician had ever diagnosed them with heart attack, stroke, coronary heart disease, or related cardiovascular conditions. Statistical adjustment accounted for major confounders, including tobacco smoking, alcohol use, obesity, diabetes, chronic kidney disease, physical inactivity, education, and income.
The broad adjustment matters because cardiovascular risk rarely travels alone. Tobacco, sedentary behavior, metabolic disease, and socioeconomic strain can cluster in the same patient, and each can blur the relationship between cannabis exposure and vascular injury.
Stroke, Not Heart Attack, Drove the Signal
Stroke produced the strongest association. Occasional users had 40% higher odds of reporting a prior stroke, and heavy users had 25% higher odds. Overall cardiovascular disease was also more common among users: low-frequency use carried 23% higher odds of reporting cardiovascular disease, while heavy use carried 21% higher odds.
Heart attack did not show a statistically significant association with cannabis use frequency in this analysis. The divergence is clinically important. It suggests the vascular effects linked to cannabis may not distribute evenly across coronary and cerebrovascular beds, or that stroke may be more vulnerable to whatever mechanism is operating here, whether that mechanism involves acute hemodynamic stress, endothelial dysfunction, thrombosis, arrhythmia, or inflammatory pathways.
One sentence captures the core concern: even occasional use was not benign in this dataset.
Why the Association Is Concerning for Bedside Practice
Cannabis is becoming more common in the United States, and its use is spreading across age groups and product types. A study author cited prior national data showing that 1 in 6 U.S. adults reported cannabis use within the past month in 2024, up from 1 in 10 in 2020. The shift is large enough to matter in daily practice, especially because many patients do not volunteer cannabis use unless they are asked directly.
This is where the biology becomes relevant. Cannabis products containing THC can alter heart rate, blood pressure, vascular tone, and autonomic balance. In patients with atherosclerotic disease or unrecognized cerebrovascular vulnerability, even transient physiologic stress could plausibly destabilize an already fragile system. Smoked products may add combustion-related vascular injury, while edible and inhaled formulations raise separate questions about dose, onset, and potency. The current analysis did not have enough detail to test those mechanisms directly, but the pattern warrants attention.
The Dose Pattern Was Not Linear
Investigators expected a straightforward rise in cardiovascular risk as use frequency increased. They did not see that. Low-frequency and heavy users both showed elevated odds, while the middle group did not emerge as a clear monotonic step between them. That irregularity complicates simple claims about cumulative exposure and suggests several possibilities: unmeasured differences in product potency, differences in lifetime exposure, selective cessation after illness, or confounding by tobacco and other behaviors that may not be fully captured in survey data.
Clinical interpretation should remain disciplined. This was an observational, cross-sectional analysis of self-reported cannabis use and prior diagnoses. The study cannot determine whether cannabis preceded stroke or caused it. It also cannot measure THC content, dose per use, or changes in consumption after diagnosis. Some participants categorized as nonusers may have been former users who stopped after becoming ill.
Tobacco Confounding Remains a Major Obstacle
Separating cannabis from tobacco remains one of the central difficulties in this literature. Many patients who use cannabis also smoke cigarettes, and tobacco is already a well-established driver of atherosclerotic cardiovascular disease. Robert L. Page II, who led the American Heart Association writing group responsible for the organization’s 2020 cannabis scientific statement, framed the problem plainly: in patients who use both substances, cannabis has often been treated as an innocent bystander, yet the accumulating observational data make that assumption harder to defend.
His clinical point is direct. Cannabis use belongs in the same cardiovascular history as tobacco, alcohol, diabetes, and blood pressure. In practice, asking about marijuana is not optional when evaluating stroke risk, secondary prevention, or unexplained vascular events in younger adults.
What Clinicians Should Take From the Data
The practical implication is not that every patient who uses cannabis will have a stroke. The implication is narrower and more clinically relevant: marijuana use, including infrequent use, should no longer be assumed to be cardiovascularly neutral. For patients with prior stroke, coronary disease, hypertension, diabetes, chronic kidney disease, or concurrent tobacco use, the exposure deserves explicit discussion rather than a casual aside.
The findings also broaden the scope of stroke prevention counseling. Patients often recognize the risk of cigarettes more readily than they recognize the cardiovascular uncertainty around cannabis. As legalization and commercial availability expand, that gap in risk perception may widen unless clinicians address it directly.
A final caution remains essential. These results come from a survey-based observational design, not a randomized trial. The association is real enough to raise concern, but not strong enough to prove causation. The next step is not assumption; it is better exposure measurement, better separation from tobacco, and prospective study of whether stroke risk tracks with THC potency, route of administration, or cumulative use over time.