Marijuana is a drug that’s hotly debated in the U.S. right now. For a long time, the use of recreational marijuana wasn’t something that was viewed as legal or even valuable in any way. In more recent years there have been changes in how people perceive marijuana, however, and some states like Colorado have even legalized its recreational use.

There is also a lot more focus on researching potential medical uses for marijuana, but despite this interest, there are still potential risks or side effects that can come with the use of marijuana.

So what about marijuana and the brain? Does marijuana kill brain cells?

Below is information and things to know about marijuana and the brain.

Article at a Glance:  

  • Research is not conclusive about marijuana’s long-term effects on the brain.  
  • Some studies show the negative effects of marijuana on a developing adolescent’s brain.  
  • Other studies show positive links between marijuana use in older adults for learning and memory.  
  • The age in which a person starts using marijuana seems to have a significant effect on the brain. 
  • It is not advisable to use marijuana to gain a “brain advantage” due to the risks involved.

Marijuana and the Brain in the Long-Term

When you use marijuana you may think about the high you experience as a result, which can often include everything from paranoia to uncontrollable fits of laughter, but beyond the high that comes with the use of marijuana, what are the effects of this drug on the brain in the long-term?

To put it simply, scientists aren’t fully aware of exactly what the relationship between marijuana and the brain are in the long-term. Some studies, primarily in animals, have shown that when people have exposure to THC which is the psychoactive component of marijuana, it can cause changes in cognition and memory later on.

This is especially true when marijuana exposure began in adolescence. Some of the research on marijuana and the brain has found that long-term users showed changes in their reward system and both structural and functional changes in the hippocampus.

Based on certain research, it’s possible that the ways marijuana and the brain interact with one another in the long-term could result in an increased likelihood of taking other drugs as well because of how the drug may affect reward pathways in the brain. This may be where the idea that marijuana is a gateway drug comes from.

One specific study that looked at the effects of marijuana on the brain in the long-term, which was called the Coronary Artery Risk Development in Young Adults study showed that while the overall lifetime exposure to marijuana in participants wasn’t linked with problems associated with processing speed or executive function, it was shown to have a negative effect on tests of verbal memory.

There have also been studies showing that long-term marijuana use disorder beginning in adolescence may have been linked to an average of up to 8 IQ points by adulthood, while people who started using marijuana in adulthood did not have the same loss of IQ points.

This study shows that when it comes to marijuana and the brain, the impact is most prevalent when younger people and adolescents become regular users of the drug, likely because the connections between their neurons are still forming.

Marijuana and the Brain in Older People

When you think of the average marijuana user you may think about younger people, but there has been increasing research looking at the effects of marijuana on the brain in older people, and the results are quite a bit different as compared to marijuana and the brain of younger people.
In studies on elderly animals who were given THC, which is the psychoactive component of marijuana, they actually showed performance improvements in tests looking learning and memory. In the same research, it seemed that the brains of elderly mice had more neurons in the hippocampus after being treated with THC and the older animals receiving THC looked more like the young, untreated mice used as controls.

The research pointed to the idea that THC and other cannabinoids found in marijuana might be protective against aging.

Other Ways Marijuana and the Brain Affect Each Other

While there are mixed research results when it comes to marijuana and the brain, there are other things to be aware of if you use marijuana.

There have been multiple studies showing that people who use marijuana regularly are at a higher risk of psychosis and in some studies, people who regularly used marijuana for years had a small volume of gray matter in certain areas of their brain, but at the same time, they had higher levels of connectivity.

So, to sum up, does marijuana kill brain cells?

Marijuana and the brain have a complex relationship to one another. Marijuana doesn’t necessarily kill brain cells, but when people start using marijuana at an early age, they have been shown to have some declines in IQ and cognitive function later on. In fact, the age at one someone starts using marijuana seems to have the biggest effect on their brain.

What’s interesting is that when older people use marijuana, it seems to do somewhat the opposite and restore some of the functionality of an aging brain to look more like a younger brain.

Of course, the studies on marijuana and the brain are still somewhat limited, and you should never try to smoke marijuana as a way to gain any sort of brain advantage because there are risks.

Medical Disclaimer

The Recovery Village aims to improve the quality of life for people struggling with substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare providers.