Recently we discussed the risks posed by cannabis use for patients with heart disease.  Another related topic is the risk posed of having a stroke.  Clearly, we want to avoid strokes. But as with the cardiac risk, the story is not simple and the data are unclear.  Let’s explore.

Types of Stroke

Like the cardiac discussion, stroke risk needs to be broken down into categories.  In particular, there are three types of stroke: embolic, lacunar, and hemorrhagic.

Embolic Stroke

The most common kind of stroke is embolic.  In this situation, a tiny blood clot or waxy cholesterol-based gunk breaks off inside an artery. It sails along in the bloodstream until the vessel narrows and it gets stuck.  When it gets stuck, it blocks further blood flow to all the tissue served by that artery and that tissue, starved of oxygen, dies. This typically occurs from either the heart itself, for example with untreated Atrial Fibrillation (AF), or from atherosclerosis of the carotid artery.  Thankfully, these underlying problems are treatable. In doing so, we dramatically reduce the risk of embolic stroke. 

Take home message: if you’re diagnosed with AF or carotid stenosis, take it seriously and follow your doctor’s treatment advice. 

Lacunar Stroke

Lacunar strokes are small areas of brain tissue death caused by the destruction of the capillary that feeds that area.  This is caused by high blood pressure over a long time period.  Usually, they aren’t too noticeable unless either they happen in a vital area (like the brain stem) or you get a lot of them.  With a lot of lacunar strokes, the brain can start to look like Swiss cheese (full of holes) and develop what we can multi-infarct dementia (dementia from many little dead areas). 

Take home message: control your blood pressure!

Thankfully, cannabis does not seem to increase the risk of either of these two kinds of stroke directly (see article on heart disease for more on the risk of cannabis and AF).  It’s the third kind of stroke, the hemorrhagic stroke, that seems to be influenced by cannabis.

Hemorrhagic Stroke

Hemorrhagic strokes are bleeding in the brain (also called Intracranial Hemorrhage or ICH).  This causes either local swelling that compresses and kills brain tissue. Or in the worst-case scenario, dumps enough blood into the head that squashes the brain and leads to death. 

Even within the category of hemorrhagic strokes, there are several types.  The most common of these are related to head trauma, which is to be avoided if possible, and unaffected by cannabis use.

cannabis and stroke - Cannabis and Stroke

Of the non-traumatic causes, sometimes there is a vessel that is malformed (called an aneurysm) that can burst and lead to bleeding.  Sometimes this runs in families, sometimes not.  Most people who have aneurysms don’t know it and lives their whole lives with nothing happening.  But, if they do rupture, it can be catastrophic. 

Other times, high blood pressure and/or atherosclerosis are likely causes.  Hence it’s important, here too, to control your blood pressure and cholesterol. 

Cannabis Use and Risk of ICH

It seems that these non-traumatic hemorrhagic strokes can be provoked by cannabis use.  The few studies we have on this are poorly done, so we must take them with a grain of salt (but not too much salt because that can raise your blood pressure).  These show about a 20% increased risk of ICH.  However, we have little idea of why cannabis use should cause an increased risk of this sort of stroke. 

It’s hard to determine the importance of this risk.  20% is not huge, but neither is it small.  And it’s not an absolute risk of 20% but rather a 20% increase in risk compared to non-users (relative risk).  Meaning the risk is 20% greater than a very small risk to begin with.  In essence, because the starting risk is small, the overall risk is still small.

To make matters more complicated, we’ve seen a few studies recently that show better outcomes for stroke victims who used cannabis.  These were more often embolic strokes, but the amount of brain tissue that died was less in the cannabis users than in non-users.  So, cannabis use seems to increase the risk of some sorts of stroke, but leads to better outcomes in other sorts of stroke.  Clearly, there is much to be learned still. 

Evaluating Cannabis Use in Patients at Risk For ICH

So, how do I advise patients in light of all of this?  For the average person, the beginning risk of ICH is low enough that the potential increase from cannabis use seems to be a lesser concern.  For people with higher than average risk, either from a personal or family history of an aneurysm or from a personal history of prior non-traumatic ICH, I would advise very careful consideration of the risk vs. benefit of using cannabis. 

Consult with a Qualified Boston Medical Marijuana Expert Today

Those considering using THC, CBD, or any type of medicine found in cannabis to help manage their condition should consider speaking to a trained medical expert who is knowledgeable about using cannabis therapeutically. Massachusetts medical marijuana doctor Jordan Tishler, M.D. sits on the faculty of Harvard Medical School and has years of experience helping patients treat pain and other ailments using cannabis. He and the team at InhaleMD stand ready to assist patients in determining whether medical marijuana is right for them. For more information, or to set up a virtual consultation with the team at InhaleMD, call us at (617) 477-8886 today.

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