Marijuana Use Risky After Aneurysm Rupture?
Smoking marijuana may be risky after aneurysmal subarachnoid hemorrhage (aSAH).
A new study shows a significant association between cannabis use and delayed cerebral ischemia (DCI) after aneurysm rupture, with nearly three times the risk of DCI and poor functional outcome.
“Aneurysms are found in 3% of the population, but only a small fraction (approximately 1%) rupture per year. Therefore, our findings affect a small portion of the overall population,” Michael T. Lawton, MD, senior author and president and CEO of Barrow Neurological Institute in Phoenix, Arizona, told Medscape Medical News.
“However, patients with a known aneurysm that is being managed conservatively with observation may want to reconsider their cannabis use in the event that their aneurysm ruptures,” said Lawton.
The study was published online January 6 in Stroke.
Largest Study to Date
The researchers reviewed the records for all 1014 patients treated for aSAH at Barrow Neurological Institute over 12 years. All of them underwent urine toxicology screening on admission.
Overall, 367 patients (36.2%) had DCI, 509 (50.2%) had poor functional outcome (modified Rankin Scale score >2) and 137 (13.5%) died.
A total of 46 (4.5%) patients (mean age, 47 years; 41% women) had a positive urine test for tetrahydrocannabinol (THC), while 968 (mean age, 56 years; 71% women) tested negative for THC.
The rate of DCI was significantly higher in THC-positive aSAH patients than in peers who tested negative (52.2% vs 35.4%; P = .03).
A positive urine screen for THC reflects cannabis use within 3 days for a single use to within roughly 30 days for frequent heavy use.
In propensity score–adjusted binary logistic regression analysis, cannabis use was independently associated with an increased likelihood of DCI (odds ratio, 2.7; 95% CI, 1.4 – 5.2; P = .003).
A prior study found a similar relationship between cannabis use and DCI in 108 patients with aSAH.
“Our study confirmed this in the largest study to date in over 1000 patients,” Lawton told Medscape Medical News.
Cocaine, methamphetamine, and tobacco use were not associated with DCI (P ≥ .29).
The study also showed a higher rate of angiographic vasospasm in cannabis users than nonusers (88.9% vs 70.5%; P = .008).
DCI was present in 50.0% of cannabis users with vasospasm vs 39.0% of nonusers (P = .17), which supports vasospasm as a potential reason for increased DCI, the researchers say.
“When people come in with ruptured aneurysms, and they have a history of cannabis use or are positive on a toxicology screen, it should raise a red flag to the treating team that they are at higher risk of vasospasm and ischemic complication,” Lawton said in an AHA news release.
“Of all the substances detected in the toxicology screen, only cannabis raised the risk of delayed cerebral ischemia,” he noted.
But the authors of an accompanying editorial in Stroke caution that more study is needed to determine the pathophysiology of cannabis-related cerebral ischemia.
“Ultimately, given the prior mixed results regarding the association of marijuana with cardiovascular complications, ischemic stroke or hemorrhagic stroke, it remains an open question whether cannabis precipitates cerebral ischemia via cerebral vasospasm and delayed cerebral ischemia,” write Feras Akbik, MD, PhD, and Ofer Sadan, MD, PhD, with Emory University School of Medicine, Atlanta.
“Future studies should attempt to better quantify the cannabis exposure in terms of chronicity, dose and temporal relationship between the cannabis use and the aneurysm rupture event, in order to better understand whether indeed marijuana can precipitate cerebral ischemia,” Akbik and Sadan say.
In the AHA news release, Robert L. Page II, PharmD, of the University of Colorado, Aurora, said the current study is not at the level of science of a randomized controlled trial, “but it is a rigorous statistical analysis involving more than 1000 patients, so the results are important and add to what we already know about possible adverse effects of marijuana use.”
Page chaired the American Heart Association (AHA) 2020 scientific statement on medical marijuana, recreational cannabis and cardiovascular health.
The statement concluded that evidence for a link between cannabis use and cardiovascular health remains unsupported, and the potential risks outweigh any potential benefits.
The study had no funding. The authors and editorial writers have no relevant disclosures.
Stroke. Published online January 6, 2022. Abstract, Editorial
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Recent Marijuana Use More Than Doubles the Risk of Complication in a Rare Type of Stroke
The study is the largest to look at the effect of THC on complications after a ruptured brain aneurysm.
There are now 36 states and four U.S. territories that allow for the medical use of marijuana, and 18 states and two territories that allow the recreational use of the drug. iStock; Canva
Among people who had a rare type of bleeding stroke called an aneurysmal subarachnoid hemorrhage, researchers found that recent marijuana users were more than twice as likely to develop a serious stroke complication that increases the risk of death and disability, according to new research.
The analysis, published on January 6 in the journal Stroke, is the largest to study the impact of THC, the substance in marijuana responsible for changes in mood and mental state, on complications after a bleeding stroke.
“We’re all vulnerable to a bleeding stroke or a ruptured aneurysm; however, if you’re a routine marijuana user, you may be predisposed to a worse outcome from a stroke after the rupture of that aneurysm,” said Michael T. Lawton, MD, the senior author of the study and the president and CEO of Barrow Neurological Institute in Phoenix, in an American Heart Association release.
Marijuana Use by Older Adults Is on the Rise
It’s estimated that 48.2 million people, or about 18 percent of Americans, used marijuana at least once in 2019, according to the Centers for Disease Control and Prevention (CDC). There are now 36 states and four U.S. territories that allow for the medical use of marijuana, and 18 states and two territories that allow the recreational use of the drug, according to the National Conference of State Legislatures (NCSL).
A study published in the Annals of Internal Medicine in January 2021 that looked at cannabis use in 171,507 adults age 55 and up between 2016 to 2018 found that men ages 60 to 64 reported the highest rates of marijuana use, with 12.6 percent of those surveyed in 2018 saying they had used the drug in the previous 30 days, up from 8.9 percent in 2016.
Over the same time period, use almost doubled in men between ages 65 and 69, rising from 4.3 percent in 2016 to 8.2 percent in 2018, and among men ages 70 to 74, from 3.2 percent to 6 percent. The authors reported less change in marijuana use among women.
What Is an Aneurysmal Subarachnoid Hemorrhage (aSAH) and What Are the Complications?
In this type of stroke, bleeding occurs in the space surrounding the brain when an aneurysm (a weak area in a blood vessel) on the surface of the brain bursts and leaks. This causes a buildup of blood around the brain and inside the skull, resulting in increased pressure on the brain.
There are about 30,000 new cases of aneurysmal subarachnoid hemorrhage in the United States every year, and it causes neurological disability in approximately two out of three people and death during the follow-up period in about two in five people. After the immediate treatment, which is to stop and prevent further bleeding, many people experience a complication called cerebral ischemia within two weeks after the event.
This happens when blood from the initial stroke irritates blood vessels, causing them to constrict enough to cut off the supply of blood to a portion of the brain, resulting in more brain damage and, in many people, death or disability.
Marijuana Use More Than Doubled the Risk of aSAH Stroke Complication
Researchers analyzed data from 1,014 people who had been treated for aneurysmal subarachnoid hemorrhage at Barrow Neurological Institute in Phoenix between January 1, 2007, and July 31, 2019.
All patients had been treated to stop the bleeding, either with an open surgery to clip off the base of the aneurysm or noninvasively with a slim tube threaded through a blood vessel to the base of the aneurysm, releasing coils that fold to fill in the space and provide a barrier to further bleeding.
The study compared the occurrence of delayed cerebral ischemia in 46 people (27 men and 19 women) with an average age of 47 years who tested positive for THC with 968 people with an average age of 56 who tested negative for THC. A positive urine screen for THC reflected cannabis exposure within three days for a single use and within approximately 30 days for frequent heavy use.
Compared with people who hadn’t used marijuana in the previous month, the recent cannabis users did not have significantly larger aneurysms or worse stroke symptoms when admitted to the hospital, and the two groups had similar cardiovascular risk factors. But recent cannabis users were significantly more likely to also test positive for other substances, including cocaine, methamphetamines, and tobacco, compared with the patients who screened negative for THC.
Among all participants, 36 percent developed delayed cerebral ischemia, 50 percent were left with moderate to severe disability; and 13.5 percent died.
After adjusting for age, sex, preexisting health conditions, and tobacco smoking, as well as recent exposure to other illegal substances, the group who tested positive for THC at last follow-up were found to be:
- 2.7 times more likely to develop delayed cerebral ischemia — 52.2 percent of those with recent cannabis use compared with 35.5 percent with no recent cannabis use
- 2.8 times more likely to have long-term moderate to severe physical disability
- 2.2 times more likely to die
“When people come in with ruptured aneurysms, and they have a history of cannabis use or are positive on a toxicology screen, it should raise a red flag to the treating team that they are at higher risk of vasospasm and ischemic complication,” Dr. Lawton said. Vasospasm occurs when a brain blood vessel narrows, blocking blood flow.
“Of all the substances detected in the toxicology screen, only cannabis raised the risk of delayed cerebral ischemia. Cocaine and meth are hypertensive drugs, so they are likely related to the actual rupture but not expected to have an impact on vasospasm.”
Authors Speculate That Marijuana May Impair Oxygen Metabolization
The study was not set up to discover how cannabis use may raise the risk of vasospasm and delayed cerebral ischemia, but the authors have a few theories.
“Cannabis may impair oxygen metabolization and energy production within cells. When stressed by a ruptured aneurysm, the cells are much more vulnerable to changes that affect the delivery of oxygen and the flow of blood to the brain,” says Lawton.
The authors acknowledge that the findings are limited because the analysis was performed retrospectively and at a single institution (rather than at several hospitals across the country).
Laboratory research by the authors is ongoing as they seek to better understand THC-related risks that may impact aneurysm formation and rupture.
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