A major new study covering data from more than 100 million people has found compelling evidence that illicit drug use substantially raises stroke risk. Younger adults who may feel invincible are not exempt.

Researchers at the University of Cambridge analysed decades of published evidence. They also applied a sophisticated genetic technique to test whether the link between drug use and stroke is truly causal, not merely coincidental. The findings appear in the International Journal of Stroke, published in March 2026. The team describes this as the most comprehensive analysis of its kind ever conducted.

Illicit Drug Use and Stroke Risk: Cocaine and Amphetamines Lead the Way

Cocaine use nearly doubles the risk of stroke, with an odds ratio of 1.96. Amphetamines carry an even heavier toll. Users face more than twice the stroke risk of non-users, with an odds ratio of 2.22.

Cannabis raises overall stroke risk by 37%. That elevated risk sits primarily within ischaemic stroke, the type caused by a blood clot cutting off blood supply to the brain.

The researchers found no statistically significant link between opioid use and overall stroke risk. They noted, however, that the opioid picture remains complex and needs further investigation.

Younger Users Face Serious Danger Too

The findings hit hardest when the researchers narrowed their focus to adults under 55. In that group, amphetamine use was linked to a 174% increase in stroke risk. Cocaine came in at 97% and cannabis at 14%.

Stroke kills and disables people of all ages. It ranks as the third leading cause of death and disability worldwide, and its global burden climbed by 70% between 1990 and 2021. The idea that recreational drug use carries little risk for young, healthy adults simply does not hold up against this evidence.

The Genetic Proof Behind Illicit Drug Use and Stroke

The Cambridge team used a method called Mendelian randomisation. This technique draws on naturally occurring genetic variants to test whether a risk factor genuinely causes a disease, rather than just appearing alongside it.

The genetic analysis linked cocaine dependence to intracerebral haemorrhage (bleeding inside the brain) and to cardioembolic stroke, where a clot forms in the heart and travels to the brain. Cannabis use disorder connected to stroke overall and to large artery stroke specifically.

Genetically predicted substance use disorder overall carried an almost eightfold increased risk of intracerebral haemorrhage, with an odds ratio of 7.79. That figure underlines just how serious the potential harm can be.

Dr Megan Ritson from the Stroke Research Group at the University of Cambridge said: “This is the most comprehensive analysis ever conducted on recreational drug use and stroke risk and provides compelling evidence that drugs like cocaine, amphetamines, and cannabis are causal risk factors for stroke. These findings give us stronger evidence to guide future research and public health strategies.”

Dr Eric Harshfield, Alzheimer’s Society Research Fellow at the Department of Clinical Neurosciences, added: “Our analysis suggests that it is these drugs themselves that increase the risk of stroke, not just other lifestyle factors among users. Taken together, our findings emphasise the importance of public health measures to reduce substance abuse as a way of helping also reduce stroke risk.”

How Drugs Physically Damage the Brain

The researchers pointed to several biological pathways that explain the connection. Sudden spikes in blood pressure sit at the top of the list. Blood vessel spasm, heart rhythm problems, increased blood clotting (particularly with cannabis) and vascular inflammation all feature too. Amphetamines carry a specific link to vasculitis, a destructive inflammation of blood vessels.

These processes drive both ischaemic stroke, caused by clots, and haemorrhagic stroke, caused by bleeding in or around the brain.

Cocaine triggers cerebral vasospasm and, with long-term use, accelerates atherosclerosis. Amphetamines provoke sudden surges in blood pressure and have a documented association with necrotising vasculitis, a severe form of vessel inflammation.

The Scale of the Problem in Numbers

The numbers make clear why this matters. In England and Wales, 8.8% of adults aged 16 to 59 reported using a drug in the year to March 2024. That represents roughly 2.9 million people. In the United States, more than half of all people aged over 12 have tried illicit drugs at least once.

Stroke already places a heavy burden on health systems and families. The contribution of substance misuse to that burden deserves far greater attention.

Why This Research Demands a Response

The Cambridge team, funded by the British Heart Foundation, called for public health efforts to treat substance misuse as a meaningful stroke risk factor. They urged healthcare professionals to ask patients about drug use when assessing stroke risk.

The evidence no longer leaves room for doubt. For anyone using cocaine, amphetamines or cannabis, the threat to brain health is real, it is measurable, and it grows with every use.

Reference

Ritson M, Markus HS, Harshfield EL. Does Illicit Drug Use Increase Stroke Risk? A Systematic Review, Meta-Analyses and Mendelian Randomization Analysis. International Journal of Stroke. 2026;00(0):1-13. DOI: 10.1177/17474930261418926

Source: dbrecoveryresources