Study: Regular pot smokers have shrunken brains


By Melissa Healy, Los Angeles Times

Experimental mice have been telling us this for years, but pot-smoking humans didn’t want to believe it could happen to them: Compared with a person who never smoked marijuana, someone who uses marijuana regularly has, on average, less gray matter in his orbital frontal cortex, a region that is a key node in the brain’s reward, motivation, decision-making and addictive behaviors network.

More ambiguously, in regular pot smokers, that region is better connected than it is in non-users: the flow of signal traffic is speedier to other parts of that motivation and decision-making network, including across the superhighway of “white matter” that connects the brain’s hemispheres.

The researchers who conducted the study speculate that the orbital frontal cortex’s greater level of “connectedness” — which is especially pronounced in people who started smoking pot early in life — may be the brain’s way of compensating for the region’s under-performing gray matter.

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Comments (22)
  1. KATHY says - Posted: November 16, 2014

    Will they ever quit complaining about what is .or what it does ?Let the pot smokers be, Its that easy,It will be here for a long time, Get over it,Its a stupid subject to begin with,LET IT BE AND LEGALIZE IT,

  2. Snow says - Posted: November 16, 2014

    “Let it be, legalize it…” In my profession, the last thing I need is to be surrounded by unmotivated, dumbed down, and “altered” coworkers. Ugh.

  3. Justice says - Posted: November 16, 2014

    Anyone surprised? Look at the ingredients like massive levels of ammonia and many other bad things when smoked are not good.

  4. KATHY says - Posted: November 16, 2014

    Have a drink it will keep you high ,Drink up,then go out and kill someone .,

  5. Steve Kubby says - Posted: November 17, 2014

    BONGWATER! All this study shows is that the government is now financing junk science in order to continue lying about the supposed dangers of cannabis. And make no mistake, this is total junk science and nothing more. Bigots desperately want to believe such junk science, but they are the ones who are addicted to alcohol, coffee, junk food, and toxic pharmaceuticals. If weed really made us dumber, why are we kicking butt in the elections? The truth is that weed makes us smarter, healthier, younger and happier. See here for details on why this study is a fraud: “Media Leaping to Extremely Faulty Conclusions from Study on the Effects of Marijuana on the Brain”

  6. VtToTahoe says - Posted: November 17, 2014

    Perhaps they had less gray matter to begin with…

  7. legal beagle says - Posted: November 17, 2014

    I think the researchers are long term users of stupid pills. How else could they come up with this gobbledygook.
    Another nail in the politicized scientific coffin.

    I don’t believe this bs study for a second.

  8. eco alarmist says - Posted: November 17, 2014

    SK : “The truth is that weed makes us smarter, healthier, younger and happier.” Younger and smarter? Really, weed is the fountain of youth? Anything else is just junk science, this is full of truthyness!!!

  9. THC says - Posted: November 17, 2014

    ammonia? Where is your data from?

  10. nature bats last says - Posted: November 17, 2014


  11. Cranky Gerald says - Posted: November 17, 2014

    Mr. Kubby once again proves he is truly off center, but still provides a spot of humor.

    He opined,
    “The truth is that weed makes us smarter, healthier, younger and happier.”

    This would seem to clearly show via expert Mr. Kubby how Pot can screw up the thinking, or more benignly perhaps proves that he just spouts junk without thinking.

    He actually said that weed “makes us…. younger”.

    Eureka! the quest for time travel has been solved…just smoke dope!

    Do it enough and you go back in time.

  12. Hmmm... says - Posted: November 17, 2014

    So that Dorito’s time-machine commercial is accurate?

  13. Tahoebluewire says - Posted: November 17, 2014

    Our teenage son has discovered pot. Pot smokers are lazy, need the nanny state to survive, and generally are total losers at life. Steve kubby…it does make you dumb. Our son has gone from As and Bs to Cs and Ds and Fs and his future is compromised because of pot. His biological father is a pothead and if it were not for his parents, he would prob still be couch surfing. I’m all for legalization, but people need to be realistic. Pot is a powerful drug just like alchohol and pills. People grow dependent on drugs. If your gonna play with fire, you better be ready for the burn.

  14. Tahoebluewire says - Posted: November 17, 2014

    And wow.. Scrubby kubby! I just read your comment again. I suppose any one can justify anything! Pot does damage the brain and lungs. Fact. Admit it dude, you are a drug addict. And so what? Big deal.. Just OWN it brah.

  15. Justice says - Posted: November 17, 2014

    Go to for one article on toxic levels compared to tobacco and what is there should shock anyone smoking cannabis, hint- it is safer to smoke corporate cancer sticks. If people need cannabis they should juice it and find a THC free form.

  16. Chief Slowroller says - Posted: November 17, 2014

    when I smoked it, it was called Dope.

    29 years since I smoked it.

    much better being Clean and Sober.

    some of you folks out there should try it.

  17. Biggerpicture says - Posted: November 17, 2014

    Justice, your statement about cannabis being more physiologically harmful than tobacco is pure unadulterated poppycock! Every year in the US over 400,000 people die from the physiological effects of tobacco use. All illicit drugs combined cause less than 1/20th (well under 20,000) the number of deaths per year in the US as does tobacco.

  18. Justice says - Posted: November 17, 2014

    Empty picture is wrong about the scientific proof and wrong that cannabis is more healthy, it isn’t. None of it is. Cannabis causes psychosis of the brain in several studies and now it is fact.

  19. Hmmm... says - Posted: November 17, 2014

    “Psychosis of the brain”. Duh-yup uh-yup. From “Psychosis is a psychiatric condition that causes a person to lose his or her sense of reality. People with psychosis have hallucinations, delusions, or disorganized thinking that cause them to lose touch with reality. Someone who is psychotic may hear voices that no one else can hear, or perceive threats that are not real. Psychosis can be very disturbing when it happens to someone you know and care about. The person might not acknowledge that anything is wrong, and may resist efforts to help.”

    Sounds a lot like YOU, inJustice. Please see a psychiatrist.

  20. sunriser2 says - Posted: November 17, 2014

    Kind of funny how 90%+ of these brain damaged stoners have stayed a step or two ahead of the supper smart law enforcement establishment for decades.

  21. Haddi T. Uptahere says - Posted: November 18, 2014

    Shrunken Brains!!!!
    Great headline, bad science.
    Read the whole article. This is just more yellow journalism concerning this subject. My big question is, why do the folks who say owning guns should be THEIR choice want to choose for others what THEY can put into their bodies?
    I have personally seen loved ones die from gunshots, lung cancer from a life of smoking tobacco, alcohol abuse and heart disease from eating unhealthy food. Never, EVER, seen or heard of ANYONE dying from marihuana use. Why the emphasis on something that is proven NOT to kill when there are so many things out there that DO kill everyday?
    Then again, the study was done in TEXAS.