Chronic cannabis use linked to significant cardiovascular risks

A new study led by UC San Francisco researchers finds that chronic cannabis use - whether it's smoked or consumed in edible form - is associated with significant cardiovascular risks. 

The report, published May 28 in JAMA Cardiology, found that people who regularly used marijuana in either form had reduced blood vessel function that was comparable to tobacco smokers. Vascular function in those who used cannabis by either means was reduced roughly by half compared to those who did not use it. 

Decreased vascular function is associated with a greater risk of heart attack, hypertension, and other cardiovascular conditions.

The researchers recruited 55 people between October 2021 and August 2024 who were outwardly healthy and either regularly smoked marijuana or consumed edibles containing tetrahydrocannabinol (THC), the primary psychoactive compound found in cannabis. 

The participants, none of whom used any form of nicotine, consumed cannabis at least three times a week for at least a year. Smokers averaged 10 years of chronic use, and those who took edibles averaged five years. 

Along with decreased vascular function, marijuana smokers had changes in their blood serum that were harmful to endothelial cells, which form the inner lining of all blood and lymphatic vessels. Those who took edibles containing THC, however, did not display these changes in blood serum. 

It's unclear how THC damages blood vessels. But the researchers said it must be happening in a way that does not involve those changes to blood serum. 

These results suggest smoking marijuana negatively affects vascular function for different reasons than ingesting THC does, according to first author Leila Mohammadi, MD, PhD, and senior author Matthew L. Springer, PhD.