Every day, the push toward national legalization of marijuana seems more and more inevitable. As more and more politicians and noted individuals come out in favor of legalizing or at least decriminalizing different amounts of pot, the mainstream acceptance of the recreational use of the drug seems like a bygone conclusion. But before we can talk about legalization, have we fully understood the health effects of marijuana?

According to a new study published in the Journal of Neuroscience, researchers from Harvard and Northwestern studied the brains of 18- to 25-year-olds, half of whom smoked pot recreationally and half of whom didn't. What they found was rather shocking: Even those who only smoked few times a week had significant brain abnormalities in the areas that control emotion and motivation.

harvard, scientists, studied, the, brains, of, pot, smokers,, and, the, results, don't, look, good,

"There is this general perspective out there that using marijuana recreationally is not a problem — that it is a safe drug," said Anne Blood, a co-author of the study. "We are seeing that this is not the case."

The science: Similar studies have found a correlation between heavy pot use and brain abnormalities, but this is the first study that has found the same link with recreational users. The 20 people in the "marijuana group" of the study smoked four times a week on average; seven only smoked once a week. Those in the control group did not smoke at all.

"We looked specifically at people who have no adverse impacts from marijuana — no problems with work, school, the law, relationships, no addiction issues," said Hans Breiter, another co-author of the study.

Using three different neuroimaging techniques, researchers then looked at the nucleus accumbens and the amygdala of the participants. These areas are responsible for gauging the benefit or loss of doing certain things, and providing feelings of reward for pleasurable activities such as food, sex and social interactions.

"This is a part of the brain that you absolutely never ever want to touch," said Breiter. "I don't want to say that these are magical parts of the brain — they are all important. But these are fundamental in terms of what people find pleasurable in the world and assessing that against the bad things."

Shockingly, every single person in the marijuana group, including those who only smoked once a week, had noticeable abnormalities, with the nucleus accumbens and the amygdala showing changes in density, volume and shape. Those who smoked more had more significant variations.

What will happen next? The study's co-authors admit that their sample size was small. Their plan now is to conduct a bigger study that not only looks at the brain abnormalities, but also relates them to functional outcomes. That would be a major and important step in this science because, as of now, the research indicates that marijuana use may cause alterations to the brain, but it's unclear what that might actually mean for users and their brains.

But for now, they are standing behind their findings.

"People think a little marijuana shouldn't cause a problem if someone is doing OK with work or school," said Breiter. "Our data directly says this is not so."


Loss of coordination and distortions in the sense of time, vision and hearing, sleepiness, reddening of the eyes, increased appetite and relaxed muscles. Heart rate can speed up. In fact, in the first hour of smoking marijuana, a user’s risk of a heart attack could increase fivefold. School performance is reduced through impaired memory and lessened ability to solve problems.


Long-term use can cause psychotic symptoms. It can also damage the lungs and the heart, worsen the symptoms of bronchitis and cause coughing and wheezing. It may reduce the body’s ability to fight lung infections and illness.

Don't confuse medical use of marijuana with smoking it!


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    According to this : "the FBI is “grappling with the question right now” of how to reform the FBI’s pot policy.
    Because.... wait for it .... they can't find enough hackers to hire that don't use marijuana. According to a recent study, hackers are 'kinda' smart. So your opinion that a users performance is reduced through impaired memory and lessened ability to solve problems is just that, an opinion. Paying credence to a study done by a group of psychiatrist who make a living by distributing a host of psychotropic drugs with much worse known side effects than marijuana could also be a sign of brain damage. People who smoke grass and 'self medicate' are a direct threat to their income because it greatly reduces the need to see a shrink or become dependent on the doctors dope.

  2. I'm copying your reply because it sums it up Beautifully!

  3. so the results that they found are that those part of their brain are different than normal right? that doesn't say that they are defective, or that they are going to have problems. they said themselves, they chose a sample of smokers "who have no adverse impacts from marijuana". So wonderful findings there: smoking pot changes the brain. whether the changes are as bad as this article make them sound, that's just opinion.

  4. Hello? It's changing your brain! Who cares about what the degree of change is. If you choose to smoke pot, you should be aware that changes are occurring to your brain and other organs. This article isn't saying it's bad to smoke, but that it does have effects no matter how much or little you smoke. Same for any other drug... people should know what it does and the possible effects. And using "kinda" smart people as an argument that it doesn't lesson ability or reduces memory is laughable. Who knows how smart they were or could have been had they not smoked. I'm all for legalizing but I also want to know what it could do in terms of long term health. I don't see it being any different than nicotine or alcohol or any other drug. Tell me the benefits and drawbacks and I'll make up my own mind, thank you.

  5. the question is only who is coming up with the findings and whose interest do these findings serve? i would also like to see a study on brain changes from cigarettes, alcohol, meditation etc... We ARE change or did I miss something there? Btw I don t smoke but kind of get tired of always having illegalized plants be put in the "bad" corner

  6. Legalizing, or making the use of something illegal is one thing. Discovering and promulgating the effects of their use is something else. Let people make their own choice based on the truth.



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