Medically Reviewed by
Jason Crawford

Article Last Updated on January 13, 2023

Humans have a long history with the cannabis plant but up until a few decades, all of the known benefits and effects were based on anecdotal evidence. With the legalization of cannabis, whether in medical form or for recreational use, the opportunities for examining its effects have significantly broadened.

In the past, due to the lack of accurate scientific information that could provide an adequate understanding of its effects, there were a lot of misconceptions about cannabis. There is still so much to discover about both the positive and negative effects of weed and all the ways it can be used, but today we’ll talk specifically about its influence on cognitive function and behavioral health.

There’s a common belief that marijuana kills brain cells, but in reality, there isn’t a ton of research on whether it can negatively impact brain function. In fact, the results are pretty conflicting and this is what we’ll be looking at today.

The Connection Between Weed and the Human Body

Marijuana and the human body are linked through the endocannabinoid system which is a complex cellular network that regulates bodily processes such as immune response, appetite, memory, learning, coordination, and many more. Its main role is to maintain homeostasis in the body.

The body naturally produces endocannabinoids whenever there is a disruption to homeostasis. They bind to the cannabinoid receptors of the endocannabinoid system and modulate their function by acting as neurotransmitters. The receptors are mainly located in the central and peripheral nervous systems.

The cannabinoids found in weed have a very similar structure to the endocannabinoids produced in the body and they bind to the cannabinoid receptors in the same way. This is what allows them to have such a prominent influence on the body and the brain.

THC (tetrahydrocannabinol), in particular, binds to these receptors more directly than its sibling CBD (cannabidiol), which is how it causes the well-known mind-altering effects. The majority of the receptors that THC binds to are found in the brain and this is why its impact is so pronounced.

Can Weed Actually Kill Brain Cells? Here’s What Science Has to Say

Most of the scientific research regarding cell death in marijuana users has been primarily focused on the effects that THC produces. There isn’t an abundance of studies, though, and the results from current research data on this topic are conflicting. 

The clinical studies done up to now have been focused either on the effects of marijuana on adults or on adolescents and young adults. Let’s see what we know so far.

Marijuana Use and Adolescents

According to available data, marijuana use seems to be more harmful to individuals younger than 25 because their brains are still in development. 

A 2014 review of literature on the effects of weed on adolescents has stated that cannabis use in adolescence can be linked to potentially damaging effects on attention and memory as well as abnormal neural functioning. According to this study, the younger an individual is, the higher the risk for permanent damage. However, they also state that there’s evidence for potential genetic vulnerability to cannabis which is also worth exploring.

On the other hand, a clinical trial on regular cannabis use in adolescence has compared the MRI scans of roughly 781 adolescents and young adults between the ages of 14-22. The majority of the participants were non-users, while a minority reported they were either casual or frequent marijuana users. The results showed that the MRI scans of the marijuana users weren’t significantly different in brain volume, grey matter, and cortical thickness than those of the non-users.

Marijuana Use and Adults

The effects of marijuana on adult brain function are inconsistent. One 2013 meta-analytical review has concluded that compared to non-users, marijuana users had a smaller hippocampus, which is a major component of the brain responsible for memory, emotions, and learning. According to the researchers, chronic and long-term cannabis use can cause cell death in this area of the brain.

Contrary to these results, a 2015 clinical trial found no association between marijuana use and the volume or shape in different brain areas. They took MRI scans of four brain areas, namely the nucleus accumbens, amygdala, hippocampus, and cerebellum of regular users and non-users. The results showed no major differences between the two groups of participants.

How Does Marijuana Compare to Tobacco and Alcohol Regarding Its Effects on Neurons?

Marijuana, tobacco, and alcohol affect different neurological systems. One key difference is that alcohol and tobacco are well-known to have neurotoxic effects on the brain, meaning they can cause brain damage. For marijuana, no such connection has been firmly established yet.

One thing they do have in common though is that their effects are much more prominent in the younger demographic, and thus more likely to be harmful.

What Are the Short-Term and Long-Term Effects of Marijuana?

The short-term effects of marijuana are the psychoactive effects it has on users, also known as being high. Depending on the method of consumption, the effects can last between 3 to 8 hours. Since marijuana influences the release of dopamine in the brain, one of the more pronounced effects is the feeling of euphoria as well as a heightening of the senses.

The short-term cognitive effects that are typically felt are confusion, fatigue, impaired concentration, difficulty making decisions, and delayed reaction time, among others.

However, THC can also cause some unpleasant, though temporary side effects. Most commonly, they include red eyes, cottonmouth (dry mouth), increased heart rate, coordination and concentration impairment, confusion, and increased anxiety and paranoia

The long-term effects are less known and are still being researched. However, it’s thought that heavy marijuana use can degrade short-term memory over time.

Bottom Line – Not Enough Evidence to Support the Claim that Cannabis Use Kills Brain Cells

Cannabis has many positive health effects, but just like any other substance, it’s not perfect and has some side effects. However, when it comes to neurotoxicity, there isn’t enough evidence to support the claim that it can kill brain cells. So far, the results are conflicting, so until there is more conclusive research, it would be wrong to include this in the list of side effects.

Additional Sources

Lu, H. C., & Mackie, K. (2016). An Introduction to the Endogenous Cannabinoid System. Biological psychiatry, 79(7), 516–525. https://doi.org/10.1016/j.biopsych.2015.07.028

NIDA. 2021, April 13. What are marijuana’s long-term effects on the brain?. Retrieved from https://www.drugabuse.gov/publications/research-reports/marijuana/what-are-marijuanas-long-term-effects-brain on 2021, April 23

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


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