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Stanford study links marijuana use to increased heart attack risk

Stanford study links marijuana use to increased heart attack risk
New research indicates THC may increase heart attack risk
New research indicates THC may increase heart attack risk
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New research indicates THC may increase heart attack risk
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New research indicates THC may increase heart attack risk

A robust new study led by researchers from Stanford University has found a strong association between increased risk of heart attack and regular marijuana use. The study indicates THC can trigger inflammation in blood vessel cells and the researchers call for medical marijuana users to be aware of potential cardiovascular risks.

Published in the journal Cell, the new study first analyzed data from around 500,000 people, looking at the relationship between marijuana use and heart attack. After controlling for age, gender and body weight, the data showed those subjects who smoked marijuana more than once a month were much more likely to have a heart attack before the age of 50 compared to non-users.

The next step was to investigate how marijuana could be increasing a person’s risk of heart attack. Focusing particularly on THC, the researchers discovered the cannabinoid did promote inflammation in human endothelial cells grown in the lab. Inflammation of endothelial cells – the cells that line the inside of blood vessels and the heart – is a key indicator of heart disease.

“Marijuana has a significantly adverse effect on the cardiovascular system,” said co-lead author on the new study, Mark Chandy. “As more states legalize marijuana use, I expect we will begin to see a rise in heart attacks and strokes in the coming years. Our studies of human cells and mice clearly outline how THC exposure initiates a damaging molecular cascade in the blood vessels. It’s not a benign drug.”

The final part of the research was an investigation to find molecules that could block the pro-inflammatory properties of THC without interrupting the psychoactive effects of the drug. The main action of THC is binding to CB1 receptors, so the researchers used machine-learning to screen a massive volume of molecules known to bind to CB1 and block the effects of THC.

One molecule that stood out was a naturally occurring substance called genistein. Found in soybeans, genistein does not effectively cross the blood-brain barrier so the researchers hypothesized it could possibly block the inflammatory effects of THC on endothelial cells while maintaining the psychoactive effects of THC on the brain. Subsequent mouse studies verified the hypothesis, showing genistein reducing endothelial dysfunction in THC-treated mice without disrupting the drug’s effects on the animal’s central nervous system.

“We didn’t see any blocking of the normal painkilling or sedating effects of THC in the mice that contribute to marijuana’s potentially useful medicinal properties,” added Chandy. “So genistein is potentially a safer drug than previous CB1 antagonists. It is already used as a nutritional supplement, and 99 percent of it stays outside the brain, so it shouldn’t cause these particular adverse side effects.”

According to the researchers, a more thorough clinical trial is needed to explore the effects of genistein on marijuana users and cardiovascular risk. The researchers also indicate CBD, another key cannabinoid in marijuana, may also have anti-inflammatory effects that could counter the potential cardiovascular effect of THC.

Prior research looking at the negative psychiatric effects of marijuana have suggested increased volumes of THC in modern strains of cannabis could lead to higher rates of adverse mental health issues. CBD, on the other hand, is a known anti-psychotic agent so it may be crucial to balance levels of these two cannabinoids in strains of medical marijuana.

Joesph Wu, senior author on the new study, said it is important medical and recreational marijuana users are aware of the potential adverse cardiovascular effects of the drug. And moving forward it will be crucial to develop ways to mitigate these adverse effects.

“There’s a growing public perception that marijuana is harmless or even beneficial,” said Wu. “Marijuana clearly has important medicinal uses, but recreational users should think carefully about excessive use.”

The new study was published in the journal Cell.

Source: Stanford Medicine

9 comments
9 comments
stb
It would be more helpful if the authors of the study quantified the added cardiovascular risk of ising THC. A study involving 500,000 people should have given enough data to do that.
FB36
An article to try to scare general public against marijuana legalization? :-)
Tobacco & alcohol are legal because they are totally harmless?

IMHO, overdose-safe drugs (like DMT, THC, LSD, Psilocybin etc) (which are actually safer than alcohol!) legally should/must be treated same as alcohol (which is really just another (similar) kind of drug)!
IMHO, just like prohibition of alcohol had caused so much crime in the past (& that is why it was repealed many years later), prohibition of many similar drugs are causing so much crime today!
We need to take lesson from history & end "War On Drugs"!!
(Not to mention, (according to many medical research) drugs like DMT, THC, LSD, Psilocybin seem to be extremely promising against (major) depression & PTSD!)
(& what benefits alcohol or tobacco have exactly (& yet they are legal)?)
WhatTheDormouseSaid
Thank you for an informative article. I am a layperson and am curious about something. I am presuming that a study involving data from 500,000 people was a lot of work and the researchers were paid. Who paid the researchers to conduct this study? Was it Stanford itself or some other entity? Does the author or anyone know? The article was copyrighted by Elsevier, which describes itself as a "world-leading provider of information solutions that enhance the performance of science, health, and technology professionals" so that does not provide any information about who paid for the study. I am hoping the author would know the answer to this question.
lon4
OK, no wonder potheads like Tofu! Been smoking/edibles very lightly for more than 50 years. Not worried. I probably will keep on enjoying a good night's sleep.
PS88
It would also be helpful if the author(s) of the study detailed the amount of cannabis consumed by participants, or perhaps the frequency of use. A detailed description of the "casual user" of cannabis would be nice. Daily user vs. weekend user?
akarp
“We didn’t see any blocking of the normal painkilling or sedating effects of THC in the mice that contribute to marijuana’s potentially useful medicinal properties,” added Chandy.

And yet the FDA maintains that Cannabis is a Schedule 1. The FDA is a JOKE! We need reform for research can be done more easily.
andrew
If they say that "As more states legalize marijuana use, I expect we will begin to see a rise in heart attacks and strokes in the coming years." are they saying that legalizing marijuana is getting more people who have never smoked it to now try it? I think that the majority of the folks that "will" be smoking it, have already been smoking it for years...has our heart attack rate increased? I'm curious... I'm 69 years old, and I've been smoking it since I was 16, plus I have heart disease...I haven't had a heart attack, so it makes me wonder, like another commenter noted, who funded this research?
Steve Jones
They controlled for "age, gender and body weight" but surely marijuana users often smoke tobacco, at least with the marijuana.
Did they control for that? If not, the non-smokers in the "non-users" group would skew the results.
EH
Good points in the other comments, to which I'll add: why did they inject the mice with THC? Surely having them eat a cannabis extract which included the other components of cannabis such as terpenes would be more relevant? Another confounder for the human results could be those who are taking it as medicine, whether as such, or because it makes them feel better, which could reflect a higher rate of underlying disease even if they themselves claim they are using it recreationally. The article summary at the journal Cell is not enough to tell anything useful. Publishing in such journals that do not provide open access should be heavily discounted by tenure review committees and grant-making institutions.