Cannabis, Cocaine and Amphetamines Linked to Sharply Higher Stroke Risk, Study Finds

Researchers at the University of Cambridge's Department of Clinical Neurosciences conducted a meta-analysis — a method that combines and compares data from multiple published studies — covering more than 100 million people. The results, published in the International Journal of Stroke, compared stroke risk among people who used recreational drugs.

Cocaine use was associated with a 96% higher stroke risk, amphetamine use with 122% higher risk, and cannabis use with about 37% higher risk. Opioid use showed no statistically significant association with stroke. Among people under 55, amphetamine use was linked to a 174% higher risk, cocaine to a 97% higher risk, and cannabis to a smaller 14% higher risk.

To test whether the drugs themselves might contribute to strokes, rather than the association simply reflecting other shared risk behaviors, the researchers used Mendelian randomization — a method that uses naturally occurring genetic variants to test for a causal relationship. Cocaine use disorders were especially linked to brain hemorrhage and cardioembolic stroke, in which a blood clot forms in the heart and travels to the brain. Cannabis use disorders were linked to stroke overall and particularly to large artery stroke. The researchers said these genetic findings support the possibility of a causal relationship, not just an association. They could not run the same genetic analysis for amphetamines because sufficiently large genetic datasets are not yet available.

Sudden increases in blood pressure, spasms and narrowing of blood vessels, abnormal heart rhythms, increased blood clotting (especially with cannabis), and inflammation of blood vessels (especially with amphetamines) are among the possible biological mechanisms, according to Dr. Megan Ritson of the Cambridge Stroke Research Group.

Problematic alcohol use was also associated with a higher risk of cardioembolic and large artery stroke, and alcohol addiction was linked to a greater overall stroke risk. In England and Wales, 8.8% of adults aged 16 to 59 — about 2.9 million people — reported using a recreational drug in the previous year, according to 2024 data cited in the study.