Marijuana Use Linked With Intracranial Stenosis in Ischemic Stroke

October 26, 2015

BALTIMORE, MD — Individuals who suffered an ischemic stroke and are regular smokers of marijuana are significantly more likely than ischemic-stroke patients who do not smoke marijuana to have an identifiable narrowing of an intracranial artery, research shows[1].

In 334 patients who had an ischemic stroke between 2005 and 2014 in France, the main cause of stroke in 58 individuals who smoked marijuana regularly was intracranial arterial stenosis. For those who did not smoke marijuana, intracranial arterial stenosis was deemed the cause of the ischemic stroke in just 14.5% of cases, a difference that was statistically significant.

"Fighting stroke must remain a priority, including in young adults," write Dr Valérie Wolff (Université de Strasbourg, France) and colleagues in their report, published in the November 3, 2015 issue of the Journal of the American College of Cardiology. "The first step may be to inform the public regarding the potential occurrence of stroke associated with cannabis use and other lifestyle risk factors, particularly nowadays when cannabis use is encouraged by new legislations worldwide."

The researchers note that marijuana smokers were significantly younger than nonusers, were more likely to be male, and more likely to engage in other behaviors, namely tobacco use and other "festive habits." As for the mechanism underlying the intracranial stenosis, Wolff and colleagues point to past studies showing reversible vasoconstriction and impaired cerebral mitochondrial respiration that can be induced by tetrahydrocannabinol.

For the 276 individuals who were not regular marijuana smokers, the main etiology of the ischemic stroke was cardiogenic embolism, which was responsible for nearly one-third of the strokes. In contrast, a cardiogenic embolism was deemed the source of ischemic stroke in 13.8% of cannabis users. Again, this difference was statistically significant.

Following the ischemic stroke, cannabis users and nonusers were equally likely to have a one-sided motor deficit, although marijuana smokers were more likely to display a visual disorder and less likely to show signs of aphasia. Functional independence poststroke was similar between the marijuana users and nonusers.

"Our data demonstrate that a favorable functional capacity is common in young patients suffering from stroke, independently of cannabis use, that is likely due to age-related enhanced brain plasticity," write Wolff and colleagues. "However, in the whole series, 18% of patients retained significant disability, and there were five deaths."

The authors report they have no relevant financial relationships.

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