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Do people who smoke marijuana have an increased risk of stroke?

This article was posted on: April 18, 2019

As more and more states legalize the use of marijuana for either recreational or medicinal purposes, it’s important for us to become knowledgeable about  potential risks and side effects. A study published in the February 16th, 2015,  issue of Medscape Reports indicates that there is a causal link between smoking marijuana and strokes.  

More Support for Causal Link Between Marijuana and Stroke

Megan BrooksFebruary 20, 2015A systematic appraisal of published case reports supports a causal link between smoking marijuana and cerebrovascular events, new research suggests.

“An increasing number of case reports link cannabis consumption to cerebrovascular events. Yet these case reports have not been scrutinized using criteria for causal inference,” explains Daniel G. Hackam, MD, PhD, Division of Clinical Pharmacology, Western University, London, Ontario, Canada.

He reviewed 34 case reports or case series of cannabis and cerebrovascular events in 64 patients with stroke (80% men; median age, 32 years). Most infarctions occurred in the anterior circulation (56%); 3 cases involved both anterior and posterior circulations (5%); and the remainder occurred in the posterior circulation (36%) or were not classified (3%).

Dr Hackam applied 4 causality criteria: temporality, adequacy of stroke workup, effects of rechallenge, and concomitant risk factors that could account for the cerebrovascular event.

In a report online February 19 in Stroke, he reports that 81% of cases exhibited a temporal relationship with cannabis use and the index event; the patient sustained a stroke within 24 hours of using cannabis.

“In 70%, the evaluation was sufficiently comprehensive to exclude other sources for stroke,” Dr Hackam reports.


§  An analysis of case reports supports a causal association between cannabis and stroke.

§  These findings, along with those of epidemiologic and mechanistic studies, suggest that clinicians should be aware of the causal association between cannabis and stroke to prevent recurrent events from subsequent cannabis use.

A stroke occurs if the flow of oxygen-rich blood to a portion of the brain is blocked. Without oxygen, brain cells start to die after a few minutes. Sudden bleeding in the brain also can cause a stroke if it damages brain cells.

If brain cells die or are damaged because of a stroke, symptoms occur in the parts of the body that these brain cells control. Examples of stroke symptoms include sudden weakness; paralysis or numbness of the face, arms, or legs (paralysis is an inability to move); trouble speaking or understanding speech; and trouble seeing.

A stroke is a serious medical condition that requires emergency care. A stroke can cause lasting brain damage, long-term disability, or even death.

Stroke. Published online February 19, 2015.

For an updated verification of these findings, see

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