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Smoking marijuana causes brain damage among young users - a study revealed changes in the areas of the brain related to pleasure and reward

This is according to a comparative MRI study between 20 young people who smoke marijuana at least once a week compared to the same number of their peers who do not use the drug. This is the first study of its kind because so far moderate use of the drug has been considered harmless, and therefore the brains of light users have not been examined so far either.

A young woman smokes marijuana. Photo: shutterstock
A young woman smokes marijuana. Photo: shutterstock 

The size and shape of two brain regions associated with emotions and motivation may be different in young people who smoke marijuana at least once a week. This is according to a new study. Findings show that recreational marijuana use may cause previously unseen changes, and the study highlights the importance of the long-term effects of light marijuana use.

Marijuana is the most commonly used drug in the US, with 18.9 million users, according to the National Survey on Drug Use and Mental Health. Marijuana is associated with disruptions in motivation, attention, learning and memory. Previous studies in which animals were exposed to the active ingredient in marijuana, tetrahydrocannabinol THC, showed that repeated exposure to it caused structural changes in brain areas involved in these functions. However, little is known about how moderate or moderate use of marijuana affects the structure of the brain in humans, especially in teenagers and young adults.

In the current study, Dr. Judy Gilman, Dr. Ann Blood, and Dr. Hans Brettier of Northwestern University, Massachusetts General Hospital, and Harvard Medical School reported that they used MRI systems to examine the brains of 18-year-olds. -25 who reported smoking marijuana at least once a week with those who did not smoke marijuana regularly. Despite psychiatric evaluations that ruled out the possibility that these people were addicts, the imaging data revealed that they had significant differences in brain structure. The nucleus accumbens - an area of ​​the brain known to be involved in the reward process - was larger and its shape and structure were different in marijuana smokers compared to non-users.

"The researchers hypothesize that even light use of marijuana can cause changes in the anatomy of the brain," says Karl Lupica, who studies the field of drug addiction at the National Institute on Drug Abuse, and who was not involved in the research. "These observations are particularly interesting because previous studies have focused primarily on the brains of heavy marijuana smokers and ignored the brains of light users.

The scientists compared the size, shape and density of the nucleus accumbens and the nucleus of the amygdala - an area of ​​the brain that plays a central role in emotions in 20 marijuana users and twenty non-users. Each marijuana user was asked to estimate their drug consumption over a three-month period, including the number of days they smoked and the amount of drug they consumed each day. The scientists found that the more the users reported using, the more abnormalities were recorded in the nucleus accumbens and the tonsil nucleus. The shape and density of the two areas differed between marijuana users and non-users.

The research challenges the idea that light marijuana use doesn't cause harm, Breittier says.

The study was funded by the National Center on Drug Abuse, the Office of National Drug Policy, the Center for the Evaluation of Anti-Drug Technologies, and the National Institute of Neurological Disorders and Stroke.

to the notice of the researchers


More of the topic in Hayadan:

21 תגובות

  1. In the last line I read who financed the research - everything became clear as day.
    Pay attention to the wordings: changes in the axillary nucleus, changes in the tonsil nucleus.
    On the other hand, in the title they rushed to write "...causes brain damage"
    The study showed "changes" in the brain and not any "damage", in fact no brain damage was proven in the above study or any scientific conclusions from the study [that were mentioned in this article at least], this is nothing but a clumsy wording of the Center for the War on Drugs.
    Enough with this false propaganda!

  2. The editor of the study herself, Dr. Judy Gilman, commented last night on the publications and said that there is no truth behind them. "I saw one headline that said our study found that marijuana causes brain damage and I was very angry," she told PolicyMic.

  3. Agree with Anonymous, the title is misleading. The study did not show that Marciaona causes harm. Therefore there is no need to state it in the title.

    It is clear to me that there will be brain changes in users. As it is clear to me that there will be brain changes in heavy book readers. or in heavy computer users or in heavy television viewers. It does not prove harm…

    But the editor thinks the title is correct, so there's nothing to do...
    I'll just point out that currently there are many studies both here and there...

    Of course, the website editor can disagree with these and show the others and indicate facts that have not been proven based on certain studies. I'm just a little sad that he doesn't look for the scientific consensus on the subject but decides based on his thoughts and partially based opinion...

  4. Dear scientists, 20 people is not a reliable or serious study.
    Investigating changes in the brains of 20 people is a foundation for a hypothesis, even though, as was said before, brain changes occur frequently (and is it surprising that changes in the amygdala were found among teenagers and students? Was the alleged research done during the exam period? 😉 )

  5. Eyal A.
    Brain changes occur regardless of marijuana smoking.
    In the future, we will be able to solve mental illnesses by sending tiny robots into the body (or brain), and with their help change the array of neurons in the brain and thus cause a behavioral change in the person.

  6. And I'm interested in how it happens that the anatomical structure of the brain changes!

    Marijuana yes or no, the claim that changes occur in the structure of the brain as a result of smoking one substance or another has potentially very interesting implications. Is the clue to control the anatomical structure of the brain at our fingertips (literally, stagedish)? In the future, will we be able to solve neurological conditions that today seem unfixable? Mental illnesses, neurological illnesses, and certainly somewhere ADHD also enters here as various sources claim about differences in the anatomy of the brain.

  7. Yedan007
    Too bad you don't even bother to read the article you refer to 🙂
    Summary of the study: A strictly supervised restricted elimination diet is a valuable instrument to assess whether ADHD is induced by food

    Do I need to translate for you what is written here??

  8. I don't understand what is dishonest in that I referred to the source, and the quote I gave is from one of the researchers. And I also mentioned who financed it. The title should be a summary of the arguments and there is no room for too much detail, in the mishna and in the article I explained everything clearly, including the need for further research.

  9. I agree with Anonymous' response, is the change seen in the study positive or negative?
    In the meantime, we have data from states in the US that have repealed cannabis ban laws and the results of this change so far in the number of suicides:
    10% decrease in suicides of men aged 20-39

    We conclude that the legalization of medical marijuana leads to an improvement in the psychological well-being of young adult males, an improvement that is reflected in fewer suicides.

    In Israel at these ages suicide is the third cause of death. The vast majority are men.

  10. Hello my father,
    In mice tested with doses suitable for a normative user (depending on the size of mice, of course) similar phenomena were found to those in this experiment (found in the references of the article).
    In heavier doses damage is indeed caused and it is even expected that a high dose, for a long time, of a substance that affects the brain will cause damage. (As you know, any substance in a high enough dose will cause damage)

    The research does not deal with this and these are not his conclusions but your conclusions.
    The unification of the three points for your claim should be scientifically justified and not according to whims of this and that.

  11. My father, the scientist you often quote used and was in favor of legalizing the drug
    Sagan was a user and advocate of marijuana. Under the pseudonym "Mr. X", he contributed an essay about smoking cannabis to the 1971 book Marihuana Reconsidered.[72][73] The essay explained that marijuana use had helped to inspire some of Sagan's works and enhance sensual and intellectual experiences.

  12. The study was funded by the National Center for Drug Abuse, the Ministry of National Drug Policy, the Center for the Evaluation of Anti-Drug Technologies
    Did we already say evolution deniers?
    Unfortunately as an aging post traumatic this is the only medicine that helped me and it was taken from me.
    Knowing my father from Haaretz newspaper as a subscriber, I expected more integrity.

  13. Let's note where this research comes from:
    The study was funded by the National Center on Drug Abuse, the Office of National Drug Policy, the Center for the Evaluation of Anti-Drug Technologies, and the National Institute of Neurological Disorders and Stroke.

    Not that I'm in favor of allowing the use of marijuana, but there are some (terminally ill, border breakers of all kinds, stressed people)
    Yes, they use it: if it promotes the agenda of these people, who am I to object?
    Selling with a doctor's prescription seems like a good arrangement to me.

  14. Anonymous - the title is correct for three reasons: also because of the studies in mice, also because of the studies in heavy users, and also because of the researcher's words.

  15. MRI is an excellent tool in the study of the brain and brain diseases.
    I think it should be used a lot more.
    for example:
    It can be used to detect and also treat the issue of battle shock.

  16. Nice research.
    A few words about the translator's wording error, which was undoubtedly innocent:
    The study they carried out does not check whether the change in density (greater density in the amygdala and the nucleus accumbens mainly) or the shape is "damage" or "benefit", but only indicates a difference.
    I looked in the article for the source of the assessment that it was damage and I did not find it - it is an exemplary scientific article.
    The title is apparently based on the last line of the article in which Breittier expressed his opinion - that the research challenges the idea that no harm was done. He is right. It remains to be seen whether damage was caused by a change in density as described in the experiment.

    Hence, the choice of the title "Smoking marijuana causes brain damage" is not a scientific choice but a cultural/moral choice (probably originating from distraction, as mentioned) and I recommend editing it and leaving the second part or rewording it.

    As they wrote in the article, this kind of research is of great importance these days when voices for legalization are increasing.
    This is also the reason that the results must be treated with the utmost caution - humans are known to "take sides" (and usually not according to pure rational considerations).

  17. And why don't they publish the study that shows that ADHD is a direct result of watching television at an early age?

    What are they afraid of?

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