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Early Marijuana Use May Impair Brain Function

An MRI of a human brain (Reigh LeBlanc/Flickr)

An MRI of a human brain (Reigh LeBlanc/Flickr)

A study released Monday by McLean Hospital in Belmont shows that individuals who start using marijuana before the age of 16 are more impaired when it comes to so-called executive function — such as planning, flexibility and abstract thinking — than those who start smoking pot at a later age.

Lead researcher Staci Gruber also says that early onset users smoke three times as much as those who start smoking marijuana later.

“We have to be clear about getting the message out that marijuana isn’t really a benign substance,” Gruber said. “The earlier you begin using it, and the more you use of it, the more significant that effect.”

Compared to control subjects, marijuana smokers show increased activation in the front area of the brain, a key region for inhibition, attention and error processing.  Additionally, the study found that those who started smoking earlier activated a different part of the brain than those who started smoking after the age of 16; this suggests there may be a neural change in response to marijuana use at an early age.



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  • Exactly

    EXACTLY! That’s why parents need to get behind legalization to take it off the black market. Right now, drug dealers are selling it to kids without asking for i.d.’s, while Alcohol is much harder for youngsters to obtain.

    I am a Conservative mother of two, and I support the legalization of marijuana because the system right now is completely failing our children.

    Marijuana’s illegal status is creating numerous problems in our society – overcrowding our jails, wasting of taxpayer dollars to enforce draconian pot laws, providing unobstructed access to the drug to our kids, non-violent Americans getting locked in jail, sick Americans not having access to an herb that would help ameliorate symptoms of many illnesses.. just to name a few.


  • jsknow

    May Impair Brain Functions?… JUST MORE DRUG WAR FEAR MONGERING PROPAGANDA!… Thousands of years of safe use by billions of people of all ages! Show me the brain dead kids that got that way from marijuana… THEY DON’T EXIST!

    Marijuana prohibition has NOTHING to do with any harm marijuana presents to society or individuals! Marijuana prohibition is all about HEMP, racism, greed and lies. Hemp is useless as a drug but it produces superior products that are much more environmentally safe than products used today. The same corporations that mostly control the government produce the inferior environmentally destructive products hemp could replace and fear competition from hemp or in the case of big pharmaceutical and alcohol companies, they fear marijuana because it’s a far safer medication and can replace a wide range of Rx and over the counter FDA approved poisons for a wide range of ailments both severe and mild and it is a far SAFER recreational drug than alcohol or tobacco. Even aspirin, non-aspirin substitutes and caffeine kill thousands every year. No one ever died from marijuana. It has been used for thousands of years and there have been over 15000 documented studies confirming its safety and efficacy for everything from headaches to cancer! Google: Granny Storm Crow’s list. It’s more like a library than a list.

    No one, of any age, in all of recorded history, anywhere on planet earth, has ever died from the ingredients in marijuana and they never will, marijuana is nontoxic.

    The World Health Organization Documents Failure of U.S. Drug Policies http://www.alternet.org/drugreporter/90295/

    Watch this FL man that gets his marijuana from the Federal government destroy all the lies about marijuana consumers being lazy and unproductive. Watch him destroy all the lies about long term heavy marijuana use being harmful. Learn the truth about marijuana: http://www.youtube.com/watch?v=lvzX8aNwxgM

    Watch this documentary about marijuana curing cancer! There are 7 parts, watch them all! Notice the resistance to even medical marijuana by government and pharmaceutical companies then ask yourself if they are really interested in public health and safety: http://www.youtube.com/watch?v=pjhT9282-Tw

    Listen to these high ranking narcotics officers expose the harms and waste of the drug war: http://www.youtube.com/watch?v=LayaGk0TMDc

    WELL WORTH READING! Free online book: The Emperor Wears No Clothes http://www.jackherer.com/thebook/chapter-one/

    Anyone that wants marijuana is already getting it, so legalizing and rationally regulating marijuana is not adding another harmful intoxicant to society, legalizing gives people the legal opportunity to make the SAFER CHOICE! Alcohol, tobacco and many Rx drugs are deadly, marijuana is not!

    Learn the truth about why marijuana is illegal. After they have the honest facts, 80% support legalizing!

    The laws prohibiting marijuana are NOT a result of any harm from marijuana. They are the result of racism, lies and greed. Read the well documented proof of that and a lot more marijuana TRUTH in these two articles, “WHY IS MARIJUANA ILLEGAL, Pete Guither” and “MARIJUANA AND HEMP THE UNTOLD STORY, Thomas J. Bouril”, click the links to those articles on this webpage:
    Internet Explorer web browser: http://jsknow.angelfire.com/home
    All Other Browsers: http://jsknow.angelfire.com/index.html

  • shep

    This is no surprise. My father, a retired pediatricain, told me about this 25 years ago. Kids who start smoking dope at a young age stunt their devolpment of mental maturity and it doesn’t seem to come back if they stop. There’s a reason it’s called dope.
    I have real mixed opinions about dope. I can see why people use it and want to legalize it, I just don’t like it myself.

  • Dave Eger

    I don’t want kids using pot, because it will just increase the price for people who are old enough to know how to appreciate it. I do however still think that it’s probably a safer way for them to get high than huffing paint or glue or sniffing markers. Those are the kind of things that KILL your executive functions at any age. therefore I have to agree with your previous poster, that legalization is the safer alternative. I think that if compared ounce for ounce, it’s also much safer than Aderal or Ritalin, which have (not surprisingly) become very popular as a recreational choice for kids who don’t have access to anything safer.

  • John Robards

    The use of ‘mind altering’ drugs by minors should not be tolerated. There is no possible justification. If a person needs something to help them cope then there are more appropriate medications. Seekers of spiritual enlightenment will already understand that it should be regarded as something special. If you do it every day then you are just self-medicating inappropriately.

    Legalization, yes but with severe sanctions for abuse. If you are under 18 then any use is abuse.

  • Dave Eger

    Yeah, if you can get anywhere close to the LD50 for pot, you should definitely be arrested for abuse. We need to realize that a lot of the other medications out there are much riskier. We need to be raising citizens who are responsible enough to self medicate, because at the end of the day, when you are prescribed anything, you choose how you take it. Well… at least until the Orwell camera system is perfected.

  • Mark

    The lady (Dave Eger) doth protest too much. Yes, there are more dangerous medications out there, but we’re talking about recreational use. We’re not talking about cancer patients. I don’t take cancer drugs when I bored on a Saturday night.

    If you’re a responsible adult, you don’t self-medicate at all. Or at least you ask your doctor first — even about OTC medications.

    As the guest said (and as many other scientists have said), we’re not the best judges of our own minds. Most of what we know about ourselves is wrong. Actual cognitive tests are required to draw a scientific conclusion.

    I used to think that smoking cigarettes relaxed my nerves. About 1 month after quitting, I discovered that I needed less calming. Marijuana relieves the effects of marijuana addiction.

  • Dave Eger

    So Mark, responsible adults don’t drink coffee? They don’t relax their muscles after a hard day of labor with some beer? You are a drone that does whatever someone who says they are smarter than you tells you to do, and nothing else?

    And we aren’t just talking recreational use. At the heart of this issue is that pot has a lot of potential to give a lot of people comfort for ailments that doctors currently prescribe much more dangerous drugs with much worse side effects than being a little extra friendly and slightly more gullible. The thing is, it’s so much easier to make money off selling pills to zombies and putting anyone who smokes weed into prison sweat shops.

    I don’t know about you, but I think I am the best judge of my own mind. No one else has seen it from the angle that I do, or spent nearly as much time with it. How many soldiers coming back with PTSD prefer smoking weed to anything else for calming their nerves, and what doctor knows enough about what these guys have been through to attempt to tell the soldiers otherwise. If you think these guys would be better off if all they have available to them was alcohol, then you don’t know enough about your substances to even be commenting, and should probably go try some weed next time you’re bored on a Saturday night.

  • Dave Eger

    Also, I don’t see how that Shakespeare you quoted is appropriate at all.

  • addd

    Mcleans is biased here as they are massive pushers of the competition, prescription drugs for children.

  • Herpderp

    This can apply to any substance of abuse. A kid’s brain is still developing at that age, and development can be affected by marijuana, alcohol, prescription drugs, etc.

  • K. Donovan

    Of course, the research was likely funded by pharmaceutical interests, thus no mention of the fact that many medications have similar effect on young brains, though no financial benefit for the companies manufacturing, distributing them and encouraging their off-label prescribing for what are increasingly acknowledged by researchers (Dr. Grinspoon at Harvard, etc.) as being no more effective than placebos.

    The conclusion is specious and gratuitous. It’s shameless for WBUR to even acknowledge such a claim.

  • Cold Comfort

    I did not smoke pot until I was 17, and then mostly infrequently. Brief period between 18-19 when it was once every weekend, then infrequently again until I was 20 when I smoked my last joint.

    There has never been doubt in my mind that my brain was damaged from even this relatively mild period of pot-smoking. My memory, reasoning, sharpness was never the same again. I’ve profoundly regretted it ever since. I tell anyone when the subject comes up, that marijuana is a potent and complex drug the mental and physical effects of which shouldn’t be taken lightly.

  • Larry

    This is scary news for most liberals on this site (and might explain some of their ides)

  • Blaze


  • nschomer

    Classic case of “correlation does not imply causation”. Did anybody think that people who are heavy marijuana users by the age of 16 might not have the “so-called executive function” skills of their peers? Weak science at best, pharmaceutical propaganda at worst.

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