Does Marijuana Actually Mess Up Your Brain In The Long Run?

Science has a lot of inconclusive things to say about the effects of marihuana on the brain, and scientific studies can only go so far.

Beauty is in the eye of the beholder, and stereotypes are too. From the point of view of a non-user, the stereotype of a pothead is probably a guy that speaks slowly and takes too long to start his next sentence. It's that character that’s hard to talk to because he loses his train of thought and ends up talking nonsense. Or it can be someone that just says “dude” a lot. It’s definitely not a flattering picture.

On the other hand, another weed smoker would probably think of a person that looks, well, less stupid. Someone who looks pretty “normal,” but reveals their occasional (or frequent) marihuana use through the things they like trippy films, music, and conversation topics. This person is probably more interesting than a non-user, and even smarter, because they’ve probably watched 2001: A Space Odyssey while high lots of times. This is all very silly and simplistic, of course. But what stereotype actually looks like a real pot smoker? Does marihuana really have an effect on our intelligence?

Science has a lot of inconclusive things to say about the effects of marihuana on the brain and scientific studies can only go so far. This is mainly due to the fact that marihuana is still illegal and criminalized in most places, while regulations make it hard for scientists to study drug use properly. Only a few studies observe individual users for long periods of time, which is necessary not only to observe differences between the brains of users and non-users, but also to assess if marihuana is what causes those differences.


Are there reasons to worry? Science writer Claudia Wallis says that weed smokers do poorly on memory, attention, and verbal ability tests when compared to non-users. And you’ve probably heard about the link between weed and psychotic symptoms. Marihuana can trigger some symptoms of schizophrenia in people who are already prone to the condition, so keep this in mind if your family has a history of mental illness. No matter how much we love to say that smoking marihuana is healthier than smoking tobacco or drinking, any psychoactive drug will have a strong psychological on us, even if there are no signs of mental health problems in our personal history.


Several tests and brain-scans suggest that marihuana affects cognitive function and memory, and in the case of prolonged use, it can reduce the volume of the hippocampus and the amygdala. These changes in brain structure and chemistry must be taken into account, but as science writer Simon J. Makin explains, all psychoactive drugs change our brains, and it’s normal for our brain structure to change over time as we develop new habits and learn new things, which can include everything from moving to a different city to taking French classes. It’s important to remember that one study can never take into account the multitude of genetic and environmental factors that influence our brain.


If you’re curious about the effects of marihuana on the brain (or you're worried about losing your intelligence) and you look for answers on the Internet, you’ll find a couple of interesting articles among millions of other articles that exaggerate or misinterpret the results of a single study. Scientific research is important, but most findings are a drop of water in the sea of information that’s out there. Remember that when you follow your curiosity, and congratulations for being curious at all: that’s a good sign, dude. At least for now, you can relax while watching The Wizard of Oz with The Dark Side of the Moon playing in the background.