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Does Cannabis Reduce the Risk of Stroke? Findings in a New Study Suggest Yes

New research has found that chronic THC increases cerebral blood flow and increases the rate at which oxygen is metabolized.

Findings in a new study published in the journal Neuropsychopharmacology suggest that prolonged cannabis use improves oxygen and blood flow to the brain, reducing the risk of clots that lead to a stroke.

The number five cause of death and a leading cause of disability in the United States, strokes, also called cerebrovascular accidents or CVAs, occur when part of the brain loses its blood supply. The lack of delivered oxygen and nutrients causes brain cells to begin dying within minutes, leading to muscle weakness, paralysis, speech issues, and other serious long-term problems.

Led by Dr. Francesca Filbey, director of Cognitive Neuroscience of Cognitive Research in Addictive Disorders at the Center for BrainHealth, researchers from the University of Texas at Dallas compared the regional brain blood oxygenation and metabolism in chronic cannabis users and non-users.

They observed that longtime cannabis users showed higher global oxygen extraction fraction and cerebral metabolic rate of oxygen compared to non-users. These effects were dose dependent, meaning they increased with the more the cannabis consumed. The researchers also found that longtime cannabis users had greater blood flow in the putamen, an area of the brain associated with habit formation and reward learning.

The increased blood flow in the putamen, the researchers noted, may be related to the ability of one cannabinoid — tetrahydrocannabinol (THC) to dilate blood vessels or additional circulatory pathways being created.

Earlier research has shown that the “primary psychoactive ingredient present in cannabis – tetrahydrocannabinol (THC) – relaxes arterial walls resulting in lower blood pressure and increased blood flow to tissues,” the study’s introduction explains.

Medical Marijuana Research

In the study, the researchers analyzed 74 chronic cannabis users and 101 non-users over a period of 60 days. The cannabis users reported at least 5,000 usages over their lifetime and daily use for at least 60 days prior to the study. All participants were required to refrain from using cannabis for 72 hours before the study so the results would be related to chronic rather than acute effects of the substance. Each of the participants had their THC metabolite levels measured using urinalysis and underwent magnetic resonance imaging (MRI).

The researchers were not able to determine whether cannabis use was directly responsible for the observed changes or if they’re reflective of other underlying differences in brain tissue metabolic rate.

Previous studies have found evidence that the compounds found in cannabis — particularly THC — regulate the dilation of arteries in the brain by binding to the endocannabinoid system’s cannabinoid 1 receptors (CB1). Research also suggests that another cannabinoid – cannabidiol (CBD) — reduces brain damage and improves recovery when administered shortly after a stroke.

“As [cannabis] becomes more widely legalized, understanding neurophysiological alterations and its effects on the brain’s health and performance are becoming increasingly relevant,” said Filbey.

The complete study, “Residual Effects of THC via Novel Measures of Brain Perfusion and Metabolism in a Large Group of Chronic Cannabis Users,” is available to access through Neuropsychopharmacology.

You can learn more about the previous research investigating cannabis’s effects on stroke by visiting our education page.