A massive new study sheds light on how cannabis affects the brain, particularly during cognitive tasks.
Researchers analyzed over 1,000 young adults and found that both heavy lifetime use and recent cannabis consumption significantly reduced brain activity during working memory tasks. This impairment was linked to worse performance on tasks requiring focus, problem-solving, and instruction-following. Brain imaging revealed that key regions responsible for decision-making and attention were affected.
Cannabis Use and Brain Function: A Groundbreaking Study
A new study published in JAMA Network Open examines how both recent and long-term cannabis use affects brain function during cognitive tasks.
As the largest study of its kind, researchers analyzed over 1,000 young adults aged 22 to 36 using brain imaging technology. They found that 63% of heavy lifetime cannabis users showed reduced brain activity during a working memory task, with a similar impact seen in 68% of recent users.
Reduced Brain Activity and Working Memory Impairment
This decrease in brain activity was linked to poorer performance on working memory — a crucial function that helps people retain and use information for tasks. For instance, working memory enables someone to follow instructions, mentally visualize concepts, or solve problems like math equations.
“As cannabis use continues to grow globally, studying its effects on human health has become increasingly important. By doing so, we can provide a well-rounded understanding of both the benefits and risks of cannabis use, empowering people to make informed decisions and fully comprehend the potential consequences,” said the study’s first author Joshua Gowin, PhD, assistant professor of radiology at the University of Colorado School of Medicine on the University of Colorado Anschutz Medical Campus.
In the study, heavy users are considered young adults who’ve used cannabis more than 1000 times over their lifetime. Whereas, using 10 to 999 times was considered a moderate user, and less than 10 times was considered a nonuser.
MRI Scans Reveal Cannabis’ Impact on Brain Function
The researchers studied the neural response of participants during a magnetic resonance imaging (MRI) session and gave them seven cognitive tasks to complete. The tasks tested working memory, reward, emotion, language, motor skills – such as tapping a finger to map brain control, relational assessment and theory of mind.
The researchers found that cannabis had a statistically significant effect on brain function during working memory tasks, meaning the observed impact is very unlikely to be due to random chance. This effect was seen in both recent and lifetime cannabis users. The impact was less significant for the other tasks.
“We applied the highest standards to our research, setting rigorous thresholds for statistical significance across all seven cognitive function tests. To minimize the risk of false positives, we employed false discovery rate (FDR) correction. While some of the other tasks indicated potential cognitive impairment, only the working memory task showed a statistically significant impact,” adds Gowin.
Key Brain Regions Affected by Heavy Cannabis Use
During working memory tasks, the researchers found heavy cannabis use appeared to reduce brain activity in certain areas of the brain (dorsolateral prefrontal cortex, dorsomedial prefrontal cortex, and anterior insula). These regions of the brain are involved in important cognitive functions such as decision-making, memory, attention, and emotional processing.
However, Gowin mentions their research also suggests that abstaining from using cannabis before doing a cognitive task could help to improve performance. “People need to be aware of their relationship with cannabis since abstaining cold turkey could disrupt their cognition as well. For example, heavy users may need to be more cautious,” Gowin says.
Unanswered Questions: The Future of Cannabis Research
He adds, “There are a lot of questions we still need answers to regarding how cannabis impacts the brain. Large, long-term studies are needed next to understand whether cannabis use directly changes brain function, how long these effects last, and the impact on different age groups.”
Reference: “Brain Function Outcomes of Recent and Lifetime Cannabis Use” by Joshua L. Gowin, Jarrod M. Ellingson, Hollis C. Karoly, Peter Manza, J. Megan Ross, Matthew E. Sloan, Jody L. Tanabe and Nora D. Volkow, 28 January 2025, JAMA Network Open.
DOI: 10.1001/jamanetworkopen.2024.57069
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51 Comments
File this under things that didn’t need scientific proof. Just interact with a stoner and you could make this conclusion. But… whatever, you can’t tell stupid people they’re stupid. Not smart enough to understand.
I use medical cannabis, I don’t think I’m stupid. I think the ignorant idiot who called me stupid is the stupid one.
😂🤣 Hi Five!
“Our study determined that marijuana impairs brain function. Marijuana Users need to know this, so that they can make better decisions.”
But marijuana use IMPAIRS BRAIN FUNCTION.
Don’t listen to the Clown .
I think this is the best comment I have read all day!!!!
I think this is case by case my friend is heavy daily user yet and has been since a teenager. He’s almost sixty, has a very successful career and can function daily.
Wow what a brainiac man.
I am curious. Did it truly impair the ablity to do the cognitive skills. Or slow the response down. Also is it smoking or eating. We know smoking and eating affects how high one may be. Also we know smoking of any kind covers the surface of the brain like a blanket. That’s why you don’t smoke around children I forget the study and I may not be saying it right.
Then there is the fact that it has shown to help ADHD users complete daily tasks and pay attention.
I wonder if it is the type also like the strain or something in it
Right because I’m sure your not stupid in some way.
Rubbish!! notice in the opening report states MORE RESEARCH IS NEEDED. WHY RELEASE THIS REPORT AND USE SCARE MUNGER TACTICS TO STOP PEOPLE SELF MEDICATING. SOMEONE HAS TAKEN A BACKHAND PAYMENT???
You’re probably correct.
Huh that’s strange, when I use it responsibly it helps me remember things from 20+ years ago.
Jeif, not all people that use canibus are stupid stoners. If it wasn’t for cannibus I’d be an opioid addict. I used it over 20 years ago to treat siadica from an auto accident. The doctor wanted me to use an opioid to manage the pain but I could function at my job on them. Thank God I was smart enough to use cannibus instead. I took it in the evenings to calm the siadica and allow my body to get good rest so it could heal itself. I used it for maybe a year, just in the evenings. Once I was better I cold turkey stopped, no withdrawls and no issues what so ever. Fast forward to 20 years of no use, another auto accident left me with permanent spinal issues and pain. I went directly to canibus for relief. It has also reduced the inflammation in my body to help my thyroid finally function within normal range after being diagnosed 15 years ago with an autoimmune disease. I NEVER have taken pharmaceuticals to treat my autoimmune disease. I’ve treated it through my diet and unbeknownst to me until I got my thyroid numbers, with cannibus because it reduces inflammation caused by the autoimmunedisease. It’s the only thing I’ve done differently. I think people should be cautious in calling people stupid for using cannibus. I do believe using it often, at a young age will have negative effects but to blanket call people stupid for using it is an uneducated response. I wonder in these studies how many people have other health issues that can also cause cognitive decline like fibromyalgia or an auto accident. I had recall issues after my accident before I started using cannibus. So which caused it? Medical research can be very subjective without knowing what conditions everyone has. For instance, I didn’t get the COVID vaccine when all the doctors told me to get it because I had an auto immune disease. The reason why was I actually am smart and didn’t just do what they told me to do…I went to the CDC website and found out that NO ONE in the clinical trials had an auto immune disease. I’m not going into all the details but that is very significant if you have one. I find the universal law of not judging others least you be judged in the same manner to be rather poignant in your comment. I’d hate for anyone to loose their cognitive function in order to see the effects of their uneducated judgment on someone else. If you ever find yourself in a place where you’re medically needy, compare the side effects of cannibus to your prescription digs and tell me who’s using deductive reasoning as to which is better. Have a wonderful day!
I totally agree. I took suffer from back pain. They won’t prescribe opioids and keep telling me it’s not bad enough to warrant surgery. Smoking weed helps with the pain and depression. How about investigating collralation between pain and depression. That would be helpful. Thank you for listening.
This is very well written. Thank you for your input, based on your personal experience with cannabis.
Take it for what it is. It’s a nedical article in JAMa. Medical doctors and pharmaceutical companies
want to keep prescribing opioid drugs to keep the dollars coming in as well as having a long history of talking bad about cannabis and THC. They could care less if you become addicted. THC etc. dies nit addict you abd you can stop it at anytime. I had a knee replacement and almost became addicted on oxyicodine even when I followed the doctors recommended doses and didn’t abuse it. I realized what was happening and stopped it had suffered withdrawal symptoms which I care not to experience again. Next knee operation will be THC.
Also, why publish an article getting everyone upset and end it by saying more research needs to be conducted?
I was diagnosed with Fibromyalgia in 2007… had to leave my career and I was 34.. and couldn’t walk without pain..Did my research controlled my diet and walked… Fast forward 20+ years Im thriving in my career … I have never felt better. It controls inflammation, pain, and helps tremendously…. The medication made me gain weight, sleep, and caused depression …
Its “cannabis”. The high potency cannabis and hemp derived THC of today is causing Cannabis Induced Psychosis at alarming rates. I recommend not using.
This could be the result of a study of 1000 young people age 22 to 36 who engaged in lifelong heavy drinking except their livers would also show damage.
Excellent point !
Hi there is a small error in the article this line appears contradictory: However, Gowin mentions their research also suggests that abstaining from using cannabis before doing a cognitive task could help to improve performance. “People need to be aware of their relationship with cannabis since abstaining cold turkey could disrupt their cognition as well. For example, heavy users may need to be more cautious,” Gowin says. – The article mentions the research suggests heavy users can see improvement by abstaining, and then the quote contradicts this. Either the mistake should be fixed or the language clarified (if both statements are true )
Seems flawed. You didn’t state how they consumed, how often, if they were using specific strains to do tasks, the THC balance correlation with the other cannabinoids, if they’re using high THC products like dabbing or are they smoking flower? There’s a LOT of holes not mentioned in this study. I can absolutely see someone who constantly takes dabs losing memory and getting irritable easily, but the long term flower smokers seem to be actually really intelligent. Flawed study.
I agree 100% with this opinion
To clarify Not the article, the users opinion
Did you follow link to the actual journal article? It would have the sort of information in the methodology section. This type of secondary story might not include that but the journal will.
They might be intelligent but they seem super lazy and unmotivated.
Super lazy and unmotivated! Well if you are already super lazy and unmotivated, weed could enhance those feelings especially if it’s indica, as it tents to have relaxing effects. Sativa has generally energizing effects for many, and can enhance creativity and productivity! Don’t generalize, cannabis can be very helpful for different ailments or just for the pleasure of its effects!
Who cares ” dab or flower” a stoner is a stoner. Our world is not improving because of stoners.
And pot compared to alcohol?
Alcohol= getting in fights, hit your wife, kick the dog, puke on new carpet, killed an innocent driver in accident, talk at a ridiculous volume. Fall down or wreck your bike. Call in sick, build beer belly shed over your junk.
Canabis= no road rage, more cautious, immediately reduces anxiety. Allows for extended focus to work, write, etc. Turn a Karen into a Nice Nancy. If e eryone got high on pot we would have World Peace for 2 hrs.
Right n!
Genius study – the person who smokes weed before work may not do as well with working memory as the person who did not smoke weed before work. Like a 60 some percent chance worse. Huh. Go figure. Then there are the thirty some percent of people who do just as well or better with working memory. Now, that is the strange finding worth additional study. The other thing, of course, is that most people who use cannabis don’t do so before work but on the weekends or at night.
Guess I’m one of those lol. Mainly use it for sleeping as I do not agree with pills.
More-over how does this study apply to people or users that have ADHD. As one said user here. I feel I have a more focused applied life style. I confidently but humbly would say I have high if not higher functionality, understanding, I’m an all around better person when I use cannabis. Thie is obviously a biased opinion as it is my own. But I do have the proof of 7 kids, a spouse, multiple businesses I own and operate.
So I feel the article is in a way to early or not presented well. In the means that it is not very specific about the full spectrum of the testing subjects. With the ever growing evolution of the brain and it’s personalized function based on which genes it has to work with. I feel this article and study is great for the small area it has tested. Let’s remember there are billions of people on the planet. All have different genomes and neural pathways built from years of that persons life. In lig of this we understand that there can be some obvious signs of brain function changing.
I would say in conclusion, that this test gives a great outlook on a very small demographic of people. There are also many people who don’t like pulp in their orange juice due to the texture. But if you change that person’s mind set going into it. Say tell them they are drinking a smoothie. They will adapt their brain to help deal with the current previously negative situation and open a new pathway for the brain to see the orange juice.
But hey it’s 10am and I have already used cannabis today(2x). So maybe I domt know what I’m talking about. Or maybe I have a better understanding than those that are not currently smelling that sweet stank of mary-jane. “I want to talk to Sampson! Fly me to the moon” everybody love everybody. Unless it’s your mother in law..
Stay away from me in traffic stoner.
I, too, would like to see how this study would compare to alcohol consumption.
Alcohol does far worse than weed does to the brain. Show some comparisons and what alcohol does.
Funny enough, the same university did such a study of alcohol vs marijuana on the brain. Though not at the scale the above article is claiming, which personally seems more biased vs interested in the details of how it all functions.
https://onlinelibrary.wiley.com/doi/abs/10.1111/add.13923
Someone got paid for this research so people will stay away (pharmaceutical companies).
Get real….
EVERYBODY who does research gets paid. Research CANNOT be done, unless someone is getting paid… that’s how it works.
The questions in research is, “who paid” to have it done.
I can’t use it. For this exact reason. Screws with my brain seriously. Very rarely smoke it, only mild types. I know others as well who have trouble as well. And a heavy heavy user who doesn’t seem to affect at all. Makes me wonder if he’d be brilliant if he never smoked((30 year user)
Really stupid people can have great memories. Einstein would forget how to get home while he was on his way home
50 years, daily use, have no memory problems. Run businesses, family and life just fine.
Whatever
This is not a revelation… Question is who funded this study? I guarantee Big Pharma’s Finger prints are all over this.
This study is probably funded by the same people who fund the studies telling you plant based meat and chesse is healtheir for you than real meat and dairy.
‘Stay away from the Extremes’.
You could have asked me 20 years ago.. I’d tell you that it will reduce memory.. like in the middle of convo lose track forget what you’re talking about. DUH
“Statistically significant” does not necessarily mean noticeable in daily life. And this study does not mention, much less address, the differences between people’s genetic makeup, the functioning and connectivity of their cannabinoid receptors or, really, much of anything except a statistical observation in a large number of people.
We do know that among heavy cannabis users, some are very highly functioning people with no apparent loss of ability, while some others show definite loss of ability. Why the differences? We don’t know yet, and we don’t know enough about the brain at the cellular level, or have the tools, to find the answers yet.
I’d also like to point out that it’s based on brain imaging, which looks only at oxygen use in a very low resolution image as a stand-in for brain function – because we don’t yet know what all those billions of cells are doing together from moment to moment, and don’t yet have the tools to find out. Brain imaging is the best tool we have at this point – and it is crude and ineffective for answering the important questions about what the brain’s cells are actually doing.
So this is not research that is sufficiently useful to make policy decisions from or life decisions from. It’s a preliminary study to come up with more precise questions – which then have to be researched when we have the tools that will enable us to do so. For daily living by actual humans, the only reliable way to find out whether cannabis negatively affects your memory is to use cannabis and track the results, to see how it affects you. How it affects your neighbor is irrelevant.