Cannabis Use Linked to Increased Stroke Risk by Ralph Teller

Marijuana use doubles risk of stroke

Two recent studies have found that cannabis significantly increases risk of having a ischemic stroke, which is caused by an interruption of blood supply to a part of the brain. The study from New Zealand found that patients with ischemic stroke/transient ischemic attack (TIA) were twice as likely to have recently used cannabis.

Lead author of the New Zealand study, Dr. Alan Barber from the University of Auckland, said a causal association between cannabis and stroke is plausible, given that cannabis use has been shown to increase sympathetic and decrease parasympathetic activity and to increase heart rate. Marijuana use is also associated with supine hypertension and postural hypotension, as well as increased cardiac output. Cannabis also reduces the oxygen-carrying capacity of blood and may lead to accelerated atherosclerosis, along with cerebral vasoconstriction.

Dr. Barber also noted that cannabis use has been associated with a 5-fold increased risk for myocardial infarction in the 60 minutes after use and with atrial fibrillation and sudden unexplained cardiovascular death.

A separate study conducted by a team led by Dr. Valérie Wolff from the University Hospital of Strasbourg, France concluded cannabis use should be considered a risk factor for ischemic stroke. The study found in many cases the strokes appeared to have occurred while the drug was actually being smoked, or within half an hour of smoking.

Dr. Wolff believes that since most cannabis smokers are young, patients under 45 years of age with symptoms of stroke should be asked about cannabis use and have their urine tested for cannabinoids.

Reduce risk of subsequent stroke by stop using the drug

Dr. Wolff is alerting other doctors to check for cannabis use especially in young people who have suffered a stroke. Dr. Wolff stated, "It is important to establish if cannabis has been the cause as they can reduce their risk of a subsequent stroke if they stop using the drug."

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