Can Smoking Marijuana Increase Stroke Risk?

It has long been known that smoking cigarettes — which can increase the buildup of plaque in blood vessels, make your blood more likely to clot, block blood flow to the heart and brain, among other cardiovascular effects — is a major cause of heart disease and stroke.

But a new study published in the Journal of the American Heart Association found that these health risks aren’t limited to cigarettes. The study found that marijuana, or cannabis, use is also linked to higher risk of heart attack and stroke. While rates of smoking cigarettes have decreased over time, a federal survey from 2019 showed more than 48 million people ages 12 and older reported using marijuana at least once – nearly double the number in 2002.

“As the use of cannabis is going up, the understanding of its risk is going down and people may think it’s safer than smoking cigarettes,” said Dr. Randolph Marshall, a neurologist and chief of the Stroke Division at NewYork-Presbyterian/Columbia University Irving Medical Center. “There has been a lot of information that’s come out about cannabis use, so it’s important to raise awareness that smoking marijuana on a regular basis can increase the same risks of stroke and heart disease as cigarettes.”

Health Matters spoke to Dr. Marshall to get a better understanding of how marijuana use can increase the risk of heart disease and stroke.

How does smoking marijuana lead to heart disease and stroke?
Dr. Marshall: There are two main reasons that cannabis might cause a stroke or heart disease. One is what’s called the hemodynamic effect, which means the cannabis can cause the blood vessels to constrict. We know that some strokes are related to the constrictive effects that happen in some people who frequently use cannabis.

The other reason is that the smoke itself contains toxins, called particulate matter. This contributes to the buildup of plaque in the blood vessels. In young people who haven’t built up a lot of plaque, this may accumulate over time and become worse. But for the constricted blood vessels, quitting the use of cannabis can reverse that risk.

How do we know these issues are related to cannabis and not tobacco?
In this study, which was based on self-reported data, the authors were able to look at people who use only cannabis, and not cigarettes. Previous studies had never separated those two groups before. They found that among those who had never used tobacco, there was still an increased risk of stroke and heart attack among those who smoked cannabis. There may have been an assumption in previous studies that people who smoke marijuana also smoke cigarettes. Many people don’t, as it turns out.

Does age play a role in these risk factors?
We know from this study that the risk is increased for both the general population and for younger adults. For men under 55 and women under 65, the odds of heart disease, heart attack or stroke were still increased. But people should be aware of the amount they smoke. The more you smoke, the higher the risk. The study found that adults who use marijuana daily had a 25 percent higher chance of having a heart attack and a 42 percent higher chance of having a stroke, but for those who smoked half as frequently, the relative risk was about half compared to those who smoked daily. Regardless of age, it’s the volume and frequency that increases your risk.

Are there other neurological affects due to frequent marijuana use?
Yes. The cognitive motor slowing effects when intoxicated are known neurologically. This is when your cognitive or mental performance slows down. And there are properties of the THC in cannabis that may cause anxiety, which can make both your heart rate and blood pressure go up. Those risks may translate to an increased risk of stroke.

If someone does choose to use cannabis, what should they be aware of in terms of neurological health?
There are documented medical benefits to using cannabis and there may also be a benefit to regulating marijuana so people know that what they’re being sold isn’t contaminated, but people shouldn’t assume that smoking marijuana is safer than smoking cigarettes. Smoking marijuana with greater frequency can still increase the risks of stroke or heart disease.

This is especially true with younger adults who smoke marijuana. Young adults may be putting themselves at greater cumulative risk if they smoke marijuana. There are a lot of different risk factors that can lead to stroke. If you are smoking marijuana and you have diabetes or high blood pressure, the marijuana will add to your overall risk. But through diet and exercise, or by working with your doctor, you can reduce the risk. And now that we know smoking marijuana has similar risks of smoking cigarettes, people can modify how they use cannabis to reduce the risk of stroke.