The risk of fatal complications in marijuana users doubles after a rare type of stroke

Research highlights:

  • In adults with a certain type of stroke, those who used marijuana within the last 3 to 30 days were more than twice as likely to have had a major stroke complication, which increases the risk of death and disability.
  • The study is the largest, examining the influence of THC, the mood-altering ingredient in marijuana, on complications after a bleeding stroke.

(NewMediaWire) – January 06, 2022DALLAS – Among people with one aneurysmal subarachnoid hemorrhage (aSAH) stroke, a type of bleeding stroke, marijuana users lately are more than twice as likely to develop a dangerous complication that can lead to death or greater disability, according to a new study published today in. has been published stroke, a peer-reviewed journal of the American Stroke Association, a breakdown of the American Heart Association.

The study is the most extensive to investigate the effects of THC or Tetrahydrocannabinol, the psychoactive component (change in a person’s mental state) of marijuana in complications following aneurysmal subarachnoid hemorrhage (a rare but severe form of stroke).

In aneurysmal subarachnoid hemorrhage, a weakened and bulging part of a blood vessel on the surface of the brain (called a ruptured aneurysm) bursts, causing bleeding in the space between the brain and the tissue that covers it. This type of stroke can be devastating, causing neurological disability in about 66% of people and death (during follow-up) in about 40%. Immediate treatment for aneurysmal subarachnoid hemorrhage focuses on stopping and preventing further bleeding. However, despite treatment, many patients may develop symptoms (such as speech or movement disorders) worsening in the 14 days following aneurysmal subarachnoid hemorrhage. This is caused by blood from the first stroke irritating the blood vessels, making them narrow enough to cut off blood supply to part of the brain (called a vasospasm), causing further brain damage. This complication, known as delayed cerebral ischemia, is a leading cause of death and disability after aSAH stroke.

“We are all prone to a bleeding stroke or a ruptured aneurysm, but if you are a routine marijuana user you may be predisposed to a worse stroke outcome after that aneurysm burst,” said Michael T. Lawton, MD, lead author of the study and President and CEO of Barrow Neurological Institute in Phoenix, Arizona.


The researchers analyzed data from more than 1,000 patients treated for aneurysmal subarachnoid hemorrhage at Barrow Neurological Institute between January 1, 2007 to July 31, 2019. All patients were treated to stop the bleeding, either by 1) open surgery to cut off the base of the aneurysm, or 2) non-invasively, by threading a thin tube through a blood vessel to the base of the aneurysm and loosening the folding coils to fill in the space and prevent further bleeding.

Urine toxicology screening was performed in all patients admitted with ruptured aneurysms. The study compared the incidence of delayed cerebral ischemia in 46 people (mean age 47 years; 41% female) who tested positive for THC (the component of cannabis, also known as marijuana, that causes a high) and 968 people (mean age. ). 56 years old, 71% female) who tested negative for THC. A positive urine test for THC reflects cannabis exposure within three days of single use and approximately 30 days of frequent heavy use.

The youngest cannabis users did not have significantly larger aneurysms or worse stroke symptoms on admission, and were no more likely to have high blood pressure or other cardiovascular risk factors than patients who tested negative for THC. However, cannabis users were also more likely to test positive for other substances, including cocaine, methamphetamines, and tobacco, compared to patients who tested negative for THC.

Of all participants, 36% developed delayed cerebral ischemia; 50% remained with moderate to severe disability; and 13.5% died.

After adjusting for several patient characteristics, as well as recent exposure to other illicit substances, patients who tested positive for THC at the final follow-up were found to have:

  • 2.7 times more likely to develop delayed cerebral ischemia;
  • 2.8 times higher probability of medium-term to severe physical disability; and
  • 2.2 times more likely to die.

“If people come into the house with ruptured aneurysms and they have a history of cannabis use or a toxicological screening test positive, this should alert treatment teams that they are at higher risk for vasospasm and ischemic complications,” Lawton said. “Of all the substances found in the toxicology screen, only cannabis increased the risk of delayed cerebral ischemia. Cocaine and meth are antihypertensive drugs, so they are likely related to the actual rupture but have no effect on vasospasm.”

The study does not specifically address how cannabis increases the risk of vasospasm and delayed cerebral ischemia. Lawton noted, “Cannabis can interfere with oxygen metabolism and energy production in cells. When cells are stressed by a ruptured aneurysm, cells are much more susceptible to changes that affect oxygen delivery and blood flow to the brain.”

One of the limitations of the study is that it is done retrospectively at a single institution and is not a head-to-head analysis of people who use marijuana and those who don’t.

Researchers are currently doing follow-up examinations in the laboratory to better understand THC-related risks that can affect the formation and rupture of aneurysms. They are also pushing for more research to examine the effects of different doses of THC on stroke complications.

“Assessing the risks and benefits of marijuana use is more important given its popularity and as more states legalize recreational marijuana use,” Lawton said.

“The current study does not correspond to the scientific level of a randomized controlled study, but is a rigorous statistical analysis with more than 1,000 patients. “Said Robert L. Page II, Pharm.D., MSPH, FAHA, chair of the writing group for the the American Heart Association 2020 cannabis statement and professor at the chair for clinical pharmacy and at the chair for physical medicine / rehabilitation at the university Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences in Aurora, Colorado.

Are co-authors Joshua S. Catapano, MD; Kavelin Rumalla, MD; Visish M. Srinivasan, MD; Mohamed A. Labib, MD, CM; Candice L. Nguyen, BS; Caleb Rutledge, MD; Redi Rahmani, MD; Jacob F. Baranoski, MD; Tyler S. Cole, MD; Ashutosh P. Jadhav, MD, Ph.D .; Andrew F. Ducruet, MD; Joseph M. Zabramski, MD; and Felipe C. Albuquerque, MD

The researchers did not provide any sources of funding for this study.

In the . published studies the American Heart Association scientific journals are peer-reviewed. The statements and conclusions in each manuscript are solely those of the study authors and do not necessarily reflect the politics or position of the association. The association does not give any assurances or guarantees for their correctness or reliability. The association is mainly financed by private individuals; Foundations and corporations (including pharmaceutical, device manufacturers, and other companies) also donate and fund specific association programs and events. The association has strict guidelines to prevent these relationships from affecting the scientific content. Income from pharmaceutical and biotech companies, device manufacturers and health insurers as well as the association’s overall financial information are available here.

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