Marijuana users are more likely to have stroke caused by stenosis. By Ingrid Torjesen.onmedica.com. October 28,  2015. Young adults who use marijuana are more likely to have strokes which are caused by stenosis, narrowing of the arteries, in the skull, than non-users, a study* published in Journal of the American College of Cardiology has found. Previous studies have found an association between marijuana use and stroke, but this study is the first to explore differences in features between strokes occurring in marijuana users and non-users, which could help researchers begin to identify possible mechanisms for stroke in marijuana users. 

The study included all patients under age 45 admitted to The University Hospital of Strasbourg in Strasbourg, France, with ischemic stroke from 2005 to 2014, creating a study cohort of 334 patients; 58 of the patients were marijuana users.
In marijuana users in the study, ischaemic stroke was more likely to be caused by intracranial arterial stenosis, a condition where there is narrowing the arteries inside the skull caused by a buildup of plaque. Intracranial arterial stenosis was found in 45% of the marijuana users compared to 14% of the non-users.
Marijuana users in the study were younger, more likely to be male, more likely to smoke tobacco, and more likely to have other lifestyle risk factors for stroke than non-users in the study.
Cardio embolism, a blood clot formed elsewhere in the body that moves to the brain, was most common cause of ischaemic stroke in non-marijuana users; 29% of strokes in non-users were caused by cardio embolism compared to only 14% in the marijuana users.
Dr Valerie Wolff, one of the researchers, said: "The first step may be to inform the public regarding the potential occurrence of stroke associated with cannabis and other lifestyle risk factors."

Journal reference:  Wolff V, et al. Characteristics and Prognosis of Ischemic Stroke in Young Cannabis Users Compared With Non-Cannabis Users. Journal of the American College of Cardiology, Volume 66, Issue 18, Pages 2052-2053. doi:10.1016/j.jacc.2015.08.867