• Suzanna Thallman

Myths About Cannabis Series: Does Cannabis Kill Brain Cells?

Updated: Nov 20, 2019


Ohio Marijuana Card Introduces: Myths About Cannabis (Series)

This will be the first article in a new series, "Myths About Cannabis," aimed at dispelling and providing context to the many social stigmas and misconceptions about cannabis that, sadly, still prevail to this day. First and foremost, the first piece in this series will address one of the most demonstrable myths surrounding cannabis use: cannabis kills brain cells.


This myth has been one of the most detrimental to the social stigma and acceptance of cannabis. It was during the Reagan administration that this smear campaign really took place, including the infamous "this is your brain on drugs" public service announcement with the egg being fried in a cooking pan.

The basis of this myth stems from a study on monkeys conducted by Dr. Robert Heath. The study, supposedly, found that structural changes were observed in brain cells of animals exposed to high doses of cannabis; however, the study does not actually report cell death, as is often alleged.


Dr. Heath's flawed study led to the myth that cannabis use leads to dead brain cells.

Heath's research allegedly found brain damage in three monkeys that had been "heavily dosed with cannabis." While this may sound alarming, the results of the study have never been replicated successfully and have actually since been discredited by larger studies, including those done by Dr. William Slikker of the National Center of Toxicological Research as well as Charles Rebert and Godron Pryor of SRI International. Neither of the two larger, better-controlled studies found "any evidence of physical alteration in the brains of monkeys exposed to daily doses of pot for up to a year."


The prevailing theory behind the original, and misleading, study conducted by Dr. Heath is that the brain alterations observed were a result - not of cannabis use - but of oxygen deprivation and brain suffocation. Many experts believe that the original study forced the monkeys to wear a gas mask that was pumped consistently with cannabis smoke, while not allowing the monkeys a proper opportunity to get fresh air. For this reason, suffocation began to occur and, as a result, dead brain cells were observed as this is one of the first things to happen to the body during oxygen deprivation.


Essentially, the study that purported the claim that cannabis kills brain cells was based on a flawed experiment that has since been discredited. As Dr. Perry Solomon, chief officer at HelloMD.com, and a retired anesthesiologist put it:

Every study shows that it just doesn’t kill brain cells. But, while studies have shown that cannabis use doesn’t lead to permanent brain damage, there is the possibility of temporary negative effects for those who use the substance.

And even then, the negative effects associated have been shown to occur on a short-term basis, with a 2001 Harvard University study finding that heavy cannabis-users had normal memory test scores within a month of testing, and found that cannabis does not cause irreversible mental defects.


Furthermore, in 2003, researchers analyzed 15 studies that had been conducted in the past on the effects of long-term cannabis use and found that cannabis users only showed a "minor" level of impairment.


It is important to distinguish that, during adolescence, the brain is not yet fully developed, meaning that high cannabis use - mainly with concerns to THC - could cause negative mental health effects, although further research is necessary to study other factors that may cause these negative effects.


We will leave this first piece of the series with an example of what an accurate cannabis PSA should look like:

What a cannabis PSA should look like!


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