Bad news for pot smokers:
double the stroke risk
By Charlene Laino / February 7, 2013 - UPDATED: May 8, 2019 / Journal Advocate, Sterling Colorado
https://www.journal-advocate.com/2013/02/07/bad-news-for-pot-smokers-double-the-stroke-risk/
https://www.journal-advocate.com/2013/02/07/bad-news-for-pot-smokers-double-the-stroke-risk/
Dr. Barber says he became interested in the topic after treating a young man with none of the traditional stroke risk
factors, such as high blood pressure. The patient admitted he was smoking pot when the symptoms began. “That
stimulated us to look at the medical literature where we found a sprinkling of case reports of one to three patients with
no typical risk factors who were smoking cannabis at the time of their stroke. Among them was a patient who recovered
and then had a second stroke when again smoking cannabis,” he says.
factors, such as high blood pressure. The patient admitted he was smoking pot when the symptoms began. “That
stimulated us to look at the medical literature where we found a sprinkling of case reports of one to three patients with
no typical risk factors who were smoking cannabis at the time of their stroke. Among them was a patient who recovered
and then had a second stroke when again smoking cannabis,” he says.
Here’s another compelling reason to think twice before lighting up a joint: Smoking pot may more than double your risk of stroke, according to a new study being presented here today at the International Stroke Conference.
In the New Zealand study, people aged 18 to 55 who had a stroke were 2.3 times more likely to test positive for marijuana in their urine than those who didn’t have a stroke.
The study doesn’t prove that smoking pot will cause a stroke. “But it provides the strongest evidence to date that a lifestyle that includes cannabis use is closely associated with a doubling of stroke risk,” says study lead author P. Alan Barber, MD, PhD, a professor of clinical neurology at the University of Auckland.
Dr. Barber says he became interested in the topic after treating a young man with none of the traditional stroke risk factors, such as high blood pressure. The patient admitted he was smoking pot when the symptoms began. “That stimulated us to look at the medical literature where we found a sprinkling of case reports of one to three patients with no typical risk factors who were smoking cannabis at the time of their stroke. Among them was a patient who recovered and then had a second stroke when again smoking cannabis,” he says.
Barber and his colleagues then decided to test young stroke patients admitted to their hospital for the presence of cannabis in their urine. The current study included 160 patients, 100 of them men, with ages ranging from 18 to 55 years. Only about 10 percent to 15 percent of all stroke victims fall into this age category; most are older, Barber notes.
Most patients (94 percent) had an ischemic stroke; 6 percent had a transient ischemic attack, often referred to as a TIA or mini-stroke. The results of their marijuana tests were compared to those from a control group of 160 patients matched for age, gender and ethnicity. The control group had not had a stroke, but had urine tests for various other reasons.
Results showed that 16 percent of stroke patients tested positive for cannabis, compared with only 8 percent of patients who had not had a stroke.
“We were fairly surprised that one in six stroke patients had recently used cannabis,” Barber says. “Given the findings, we strongly advise that young stroke patients who smoke marijuana don’t use it again.”
The researchers also performed a second statistical analysis that took into account a patient’s age, sex, and ethnicity. The only factor associated with increased risk of stroke or TIA was the use of marijuana. It raised risk by 2.3-fold.
A major problem with the study was that the researchers had no information on the traditional stroke risk factors in the comparison group. That proved particularly problematic when it came to smoking cigarettes — a known stroke risk factor.
“We know that all but one of the stroke patients who were cannabis users also used tobacco. We do not know how much — if at all — people in the comparison group used tobacco,” Barber says.
However, he says he believes the stroke risk is from marijuana use and not tobacco. “For starters, this is a young age group to be having strokes, and many didn’t have any of the traditional risk factors. And some patients had a stroke while actually smoking cannabis,” he says.
It also makes sense from a physiological point of view, Barber says. “We know cannabis can cause changes in blood pressure and heart rate that are associated with increased stroke risk. Importantly, it can also cause heart palpitations, [which can be a sign of atrial fibrillation]. And atrial fibrillation is very strongly associated with stroke.”
The findings are especially important, he adds, given that smoking pot may be considered relatively harmless for your health — “safer than drinking alcohol or using other drugs.”
Add to that the fact that more than a third of states have legalized its use” in one form or another, “and it’s imperative to know the risks,” says Barber.
Other research has linked marijuana to lung disease, heart attacks, and problems with brain development, he says. But proponents of marijuana note that other studies show no such links and that still other work has shown marijuana to have medicinal uses ranging from alleviating nausea to managing chronic pain.
“This is a very interesting and important observation,” says American Stroke Association spokesperson Lee H. Schwamm, MD, director of stroke services at Massachusetts General Hospital and professor of neurology at Harvard Medical School, who was not involved in the study.
The real question, he says, is whether marijuana is the cause of stroke or representative of another risk factor. “For example, the impact of cigarette smoking may or may not be relevant; we simply don’t know,” Dr. Schwamm says.
Barber says his next step is to conduct a similar study where he gathers and takes into account information on tobacco use and other stroke risk factors in a larger control group.
Research presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.
In the New Zealand study, people aged 18 to 55 who had a stroke were 2.3 times more likely to test positive for marijuana in their urine than those who didn’t have a stroke.
The study doesn’t prove that smoking pot will cause a stroke. “But it provides the strongest evidence to date that a lifestyle that includes cannabis use is closely associated with a doubling of stroke risk,” says study lead author P. Alan Barber, MD, PhD, a professor of clinical neurology at the University of Auckland.
Dr. Barber says he became interested in the topic after treating a young man with none of the traditional stroke risk factors, such as high blood pressure. The patient admitted he was smoking pot when the symptoms began. “That stimulated us to look at the medical literature where we found a sprinkling of case reports of one to three patients with no typical risk factors who were smoking cannabis at the time of their stroke. Among them was a patient who recovered and then had a second stroke when again smoking cannabis,” he says.
Barber and his colleagues then decided to test young stroke patients admitted to their hospital for the presence of cannabis in their urine. The current study included 160 patients, 100 of them men, with ages ranging from 18 to 55 years. Only about 10 percent to 15 percent of all stroke victims fall into this age category; most are older, Barber notes.
Most patients (94 percent) had an ischemic stroke; 6 percent had a transient ischemic attack, often referred to as a TIA or mini-stroke. The results of their marijuana tests were compared to those from a control group of 160 patients matched for age, gender and ethnicity. The control group had not had a stroke, but had urine tests for various other reasons.
Results showed that 16 percent of stroke patients tested positive for cannabis, compared with only 8 percent of patients who had not had a stroke.
“We were fairly surprised that one in six stroke patients had recently used cannabis,” Barber says. “Given the findings, we strongly advise that young stroke patients who smoke marijuana don’t use it again.”
The researchers also performed a second statistical analysis that took into account a patient’s age, sex, and ethnicity. The only factor associated with increased risk of stroke or TIA was the use of marijuana. It raised risk by 2.3-fold.
A major problem with the study was that the researchers had no information on the traditional stroke risk factors in the comparison group. That proved particularly problematic when it came to smoking cigarettes — a known stroke risk factor.
“We know that all but one of the stroke patients who were cannabis users also used tobacco. We do not know how much — if at all — people in the comparison group used tobacco,” Barber says.
However, he says he believes the stroke risk is from marijuana use and not tobacco. “For starters, this is a young age group to be having strokes, and many didn’t have any of the traditional risk factors. And some patients had a stroke while actually smoking cannabis,” he says.
It also makes sense from a physiological point of view, Barber says. “We know cannabis can cause changes in blood pressure and heart rate that are associated with increased stroke risk. Importantly, it can also cause heart palpitations, [which can be a sign of atrial fibrillation]. And atrial fibrillation is very strongly associated with stroke.”
The findings are especially important, he adds, given that smoking pot may be considered relatively harmless for your health — “safer than drinking alcohol or using other drugs.”
Add to that the fact that more than a third of states have legalized its use” in one form or another, “and it’s imperative to know the risks,” says Barber.
Other research has linked marijuana to lung disease, heart attacks, and problems with brain development, he says. But proponents of marijuana note that other studies show no such links and that still other work has shown marijuana to have medicinal uses ranging from alleviating nausea to managing chronic pain.
“This is a very interesting and important observation,” says American Stroke Association spokesperson Lee H. Schwamm, MD, director of stroke services at Massachusetts General Hospital and professor of neurology at Harvard Medical School, who was not involved in the study.
The real question, he says, is whether marijuana is the cause of stroke or representative of another risk factor. “For example, the impact of cigarette smoking may or may not be relevant; we simply don’t know,” Dr. Schwamm says.
Barber says his next step is to conduct a similar study where he gathers and takes into account information on tobacco use and other stroke risk factors in a larger control group.
Research presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.