Cannabis, Cocaine, and Amphetamines All Linked to Higher Stroke Risk in Major Analysis | Research

The takeaway

Cannabis use was associated with 37% higher stroke risk in observational studies, and genetic analysis confirmed cannabis use disorder is causally linked to large artery stroke.

Cardiologists, neurologists, cannabis users, public health professionals, and anyone interested in cardiovascular risks of substance use.

37% higher stroke risk; genetic evidence confirms causation

What the researchers found

Meta-analysis of 32 studies (>100 million participants) found cannabis associated with 37% higher stroke risk (OR 1.37), cocaine with 96% higher risk (OR 1.96), and amphetamines with 122% higher risk (OR 2.22). Mendelian randomization confirmed cannabis use disorder was causally associated with any stroke (OR 1.11) and large artery stroke (OR 1.35).

Why it matters

The Mendelian randomization component is crucial because it uses genetic variation to approximate a natural experiment, providing stronger evidence for causation than observational studies alone. Finding that cannabis use disorder is genetically linked to large artery stroke is a significant public health signal.

The numbers in context

32 studies, >100 million participants. Cannabis OR 1.37 (1.14-1.65). Cocaine OR 1.96 (1.27-3.01). Amphetamines OR 2.22 (1.40-3.53). MR: cannabis use disorder to any stroke OR 1.11, to large artery stroke OR 1.35. Substance use disorder overall to intracerebral hemorrhage OR 7.79.

How the study worked

Systematic review and meta-analysis of 32 observational studies, plus two-sample Mendelian randomization using genome-wide association data to test causal relationships between drug exposures and stroke subtypes.

What this study cannot tell us

Observational meta-analysis showed heterogeneity and small-study effects for cannabis. Mendelian randomization assumes certain conditions (no pleiotropy, relevant instruments) that may not be perfectly met. Cannabis use disorder genes may also influence other behaviors.

How to read the evidence

Combines large meta-analysis with Mendelian randomization, providing both observational and genetic evidence. Published in International Journal of Stroke.

When this study was published

2026 study.

The bigger picture

As cannabis use increases globally, understanding its cardiovascular risks becomes more pressing. This study provides the strongest evidence to date that cannabis use disorder is causally linked to stroke, particularly large artery stroke, which is among the most disabling subtypes.

Questions still open

Does the risk apply to casual use or only to cannabis use disorder? What biological mechanism links cannabis to large artery stroke specifically?

Common questions

Does cannabis cause strokes?

This study provides the strongest evidence yet that cannabis use disorder is causally linked to stroke. Observational data showed 37% higher risk, and genetic analysis specifically linked cannabis use disorder to large artery stroke.

How does cannabis compare to other drugs for stroke risk?

Amphetamines showed the highest risk (122% increase), followed by cocaine (96%) and cannabis (37%). However, cannabis is far more widely used, so the population-level impact may be substantial.

Read the original research

Does Illicit Drug Use Increase Stroke Risk? A Systematic review, Meta-Analyses and Mendelian Randomization analysis.

International journal of stroke : official journal of the International Stroke Society, 17474930261418926

View on PubMed ↗Publisher’s paper ↗

Citation

Ritson, Megan; Markus, Hugh S; Harshfield, Eric L. (2026). Does Illicit Drug Use Increase Stroke Risk? A Systematic review, Meta-Analyses and Mendelian Randomization analysis.. International journal of stroke : official journal of the International Stroke Society, 17474930261418926. https://doi.org/10.1177/17474930261418926