Stroke is one of the most serious health problems in the world. It happens when blood flow to the brain is suddenly blocked or when a blood vessel in the brain bursts. Without oxygen and nutrients from the blood, brain cells begin to die within minutes.
Stroke can lead to long‑term disability, problems with speech or movement, memory loss, or death. Around the world, stroke is currently the third leading cause of death and disability combined.
Many strokes are linked to factors that people can change. Doctors have long known that high blood pressure, smoking, poor diet, lack of exercise, obesity, and heavy alcohol use can all increase the chance of stroke. Because these factors can be modified, public health experts often focus on lifestyle changes to reduce stroke risk.
Recently, scientists have also begun to look more closely at the role of recreational drugs. Drugs such as cannabis, cocaine, and amphetamines are widely used in many countries. In England and Wales, for example, government data from 2024 shows that about 8.8 percent of adults between the ages of 16 and 59 reported using a recreational drug in the previous year.
That equals roughly 2.9 million people. In the United States, surveys suggest that more than half of people over the age of 12 have tried drugs such as cannabis, cocaine, or opiates at least once in their lifetime.
Although earlier studies suggested that drug use might increase stroke risk, the results were not always consistent. Some studies found strong links, while others found weaker connections.
In addition, many earlier studies were observational. This means they could only show that drug use and stroke occurred together, but they could not prove that the drugs themselves actually caused the stroke.
To investigate this question more carefully, researchers at the University of Cambridge carried out one of the largest studies ever conducted on this topic. The team came from the Department of Clinical Neurosciences and analyzed health data from more than 100 million people. Their findings were published in the scientific journal International Journal of Stroke.
The researchers first performed a type of study called a meta‑analysis. In a meta‑analysis, scientists combine data from many different studies and analyze them together.
This approach allows researchers to see patterns that may not be clear in smaller studies. By pooling results from large numbers of people, they can reach stronger and more reliable conclusions.
When the researchers analyzed the combined data, they discovered that several recreational drugs were strongly linked to a higher risk of stroke. Cocaine use was associated with about a 96 percent increase in stroke risk.
Amphetamine use increased the risk even more, by about 122 percent. Cannabis use was also linked to a higher risk, although the increase was smaller at around 37 percent.
The scientists then looked specifically at younger adults. When the analysis was limited to people under the age of 55, the effects became even more striking. Amphetamine use was linked to almost three times the normal risk of stroke, representing a 174 percent increase. Cocaine use nearly doubled the risk, while cannabis still showed a smaller but noticeable increase.
Interestingly, the researchers did not find a statistically significant connection between opioid use and stroke risk in their analysis.
To understand whether the drugs themselves might actually cause strokes, the team performed a second type of analysis called Mendelian randomization. This method uses naturally occurring genetic differences between people to help determine whether a factor truly causes a disease rather than simply appearing alongside it.
The genetic analysis provided further evidence that some drug use may directly contribute to stroke. The researchers found that cocaine use disorders were strongly linked to certain types of stroke, including brain hemorrhage and cardioembolic stroke.
In cardioembolic stroke, a blood clot forms in the heart and then travels through the bloodstream to the brain, where it blocks an artery.
Cannabis use disorders were also associated with stroke overall, especially a form known as large artery stroke, which occurs when a major blood vessel supplying the brain becomes blocked.
The genetic analysis also revealed that problematic alcohol use increased the risk of certain stroke types. However, the researchers were unable to perform the same genetic analysis for amphetamines because there are not yet large genetic datasets available that track amphetamine use.
The scientists believe there are several biological reasons why these drugs might trigger strokes. Many recreational drugs can cause sudden increases in blood pressure, which places stress on blood vessels in the brain.
Some drugs can cause blood vessels to tighten or spasm, reducing blood flow. Others can disturb heart rhythm, which increases the chance of blood clots forming.
Some substances may also increase blood clotting or trigger inflammation in blood vessels. Amphetamines, for example, may cause a condition called vasculitis, where blood vessels become inflamed and damaged.
All of these processes are known to contribute to both ischemic strokes, caused by blood clots, and hemorrhagic strokes, caused by bleeding in the brain.
Dr. Megan Ritson from the Stroke Research Group at the University of Cambridge explained that this study is the most comprehensive analysis so far examining recreational drug use and stroke risk. According to the researchers, the findings provide strong evidence that drugs such as cocaine, amphetamines, and cannabis may act as direct risk factors for stroke.
Dr. Eric Harshfield, another member of the research team, said the results suggest that the drugs themselves play an important role in raising stroke risk. In other words, the increased risk cannot be explained only by other unhealthy behaviors sometimes seen among drug users.
Overall, this research provides important insights for public health. The large size of the study, covering more than 100 million people, gives the findings strong statistical power. The combination of meta‑analysis and genetic analysis strengthens the argument that certain recreational drugs may directly contribute to stroke risk.
However, the study also has limitations. Some drug use may be underreported in surveys, and the research cannot fully account for every lifestyle factor that might influence stroke risk. In addition, more genetic data will be needed to better understand the effects of some substances such as amphetamines.
Even with these limitations, the findings highlight a clear message. Reducing recreational drug use could play an important role in lowering stroke risk, particularly among younger adults. Public health campaigns, education, and improved addiction treatment programs may help reduce these preventable strokes in the future.
If you care about stroke, please read studies that diets high in flavonoids could help reduce stroke risk, and MIND diet could slow down cognitive decline after stroke.
For more health information, please see recent studies about antioxidants that could help reduce the risk of dementia, and tea and coffee may help lower your risk of stroke, dementia.
Copyright © 2026 Knowridge Science Report. All rights reserved.
