Even Casual Marijuana Use May Not Be Benign

I don’t use recreational drugs. Never have. There are several reasons for that. For one thing, the only thing I really have going for me is my brain and I’ve never felt that putting that at risk was worth it. Additionally, my family tends to have what are referred to as idiosyncratic or paradoxical reactions to drugs. You know those warnings in fine print that you receive on the handouts that accompany prescription medicines these days? The ones that begin “In some rare cases…” That’s me. Example: one of my siblings was recently prescribed post-operative pain medication. It induced extreme pain.

All of that notwithstanding I’ve long felt that marijuana should be legalized or, at the very least, it should be legalized for medical purposes. However, findings like this make me wonder about the prudence of that course of action:

Young adults who used marijuana only recreationally showed significant abnormalities in two key brain regions that are important in emotion and motivation, scientists report. The study was a collaboration between Northwestern Medicine and Massachusetts General Hospital/Harvard Medical School.

This is the first study to show casual use of marijuana is related to major brain changes. It showed the degree of brain abnormalities in these regions is directly related to the number of joints a person smoked per week. The more joints a person smoked, the more abnormal the shape, volume and density of the brain regions.

“This study raises a strong challenge to the idea that casual marijuana use isn’t associated with bad consequences,” said corresponding and co-senior study author Hans Breiter, M.D. He is a professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine and a psychiatrist at Northwestern Memorial Hospital.

“Some of these people only used marijuana to get high once or twice a week,” Breiter said. “People think a little recreational use shouldn’t cause a problem, if someone is doing OK with work or school. Our data directly says this is not the case.”

The study was small and local and, honestly, there could be other explanations for the results they found but it’s interesting.

Abnormal development in the areas of the brain they studied is associated with abnormal responses to learning, fear, aggression, and impulsivity, just to name a few. If there’s anything we need more of, it’s indifferent or unmotivated kids with learning difficulties.

As I see things, the present spirit of the times is moving in the direction of some sort of legalization of marijuana. We might want to think about some of the more longitudinal implications of that before getting too far down that road.

19 comments… add one
  • michael reynolds

    Marijuana clearly has an impact on motivation. So do lots of things. Realistically, as a father of teenagers, the choice is not marijuana or no marijuana, it’s marijuana or booze or pills. To the extent that I can affect that I’ll try to bend them away from things which are 1) physically addictive or 2) fatal. Looking at the big menu of “stuff your kids might do,” I’ll take weed over every other likely choice.

    As for damage more broadly, take a poll of talented artists in every creative field, art, music, dance, literature, and I’d bet a nickel the pot-smoking rate is around 100% for “have ever” and a good 70% for “currently smoke.” Ditto of course for booze.

    Now, if we had a way of keeping alive the child’s imagination we are all born with, maybe drugs would be less helpful. But we do all we can to obliterate children’s imaginations. I’ve done book tour at the elementary, middle school and high school levels, and it’s depressing how much is lost thanks to an educational system that demands we all color within the lines, even if our name is Picasso. Schools attack the very attribute that is the necessary ingredient of artistic creativity.

    Rather than worry about the weed that allows some creative souls to recapture some of what they’ve lost, maybe we could resist the urge to demand that children be turned into drones in the first place. Society is increasingly committed to giving kids performance-enhancing drugs like Adderall and Ritalin so that hey can climb the credentialing ladder. But God forbid that after a 12 or 14 hour work day a cranked-up kid should smoke a joint to take the edge off. Because that would alter his brain in ways not directly helpful to taking the next step toward student loans and eventual employment in a field completely unrelated to his education.

    tl;dr: We’re shoveling amphetamines into kid’s mouths so they can score on standardized tests, but we’re worried about the least harmful of recreational drugs?

  • ...

    I remember a guy named Scott from high school. At some point he started smoking a LOT of dope. We started calling him Swatty. I ran into a couple of years after high school. “Hey, Swatty! Long time no see!”

    “Aw, dude, don’t call me that. I don’t smoke that stuff anymore.”

    “Yeah? Why not?”

    “‘Cause POT makes you STUPID.”

    I laughed and didn’t get off the correct response of “Why do you think they call it dope?” LL Cool J would have been disappointed in me. (See the Urban Dictionary for the various uses of dope. I use the term as a non-user would.)

  • Guarneri

    “The study was a collaboration between Northwestern Medicine and Massachusetts General Hospital/Harvard Medical School.”

    Fucking blue blood, north side killjoys…..

    But I’m with Reynolds. And anyway, we conservative/libertarians need a heavy dose of “imagination” and “empathy” lest we succumb to sane views on finance and investment and, god forbid, sane public policy………..

  • The legal drinking age is 21 in all 50 states. Even if recreational marijuana use were legalized at the federal level, there is zero likelihood that the legal age for it will be below 21.

  • michael reynolds

    there is zero likelihood that the legal age for it will be below 21.

    And zero likelihood that’ll stop the kids. My son would have as much trouble buying weed at school as I’d have picking up a bottle of Scotch at Bev Mo.

  • jan

    Age limits rarely stop kids from doing something they are age-restricted to do.

    Nonetheless, if, weed is made legal, then schools should also insert more creatively interesting, informative educational courses in their curriculum, dealing with the emotional/biological repercussions of smoking at a young age, as well as the implications it might have in their adult years. They do it for sex and birth control, why not for cannabis.

    While I personally have a lot of reservations about pot-smoking, except for medicinal purposes, I’m also aware that such a stance is rapidly becoming a minority one. I just hope people will give cautious consideration for all the unintended consequences society faces in giving legitimacy to something like weed that, IMO, is far from innocuous.

  • This study is a big fail,people need to look deeper into story’s before they start spewing the H8.On a side note look who is fronting the money for this study LOL FAIL-Sauce

  • michael reynolds


    I absolutely agree re: honest education on weed as in all things. It would be a nice break from decades of lies and scare tactics that succeeded only in convincing kids to ignore whatever the school had to say on the subject of drugs.

  • Will Truman

    Something shouldn’t have to be competently benign in order for it to be legally permissible.

  • steve

    This study is troubling. There are, supposedly, 15-20 million pot smokers in the country. These findings have never been reported before until they did this study on 40 people. Why hasnt this been noticed before? It should not be a rare finding.

    I agree that kids should not smoke pot, or drink for that matter, on their own. I would keep it illegal until age 16. After that, leave it up to parents. Kids caught earlier should not face jail, but counseling and/or community service or maybe forced to work on pot farms. That would teach them.


  • Why hasnt this been noticed before?

    My guess is that improvements in quality and declines in cost of imaging have something to do with it.

    I agree with much of what you wrote in that comment, Steve.

    Another possible factor: it ain’t your father’s marijuana.

  • Jimbino

    Wow. It seems to me that sex maims and kills more people around the world than does marijuana. And you can’t pass marijuana addiction on to another person, though you could pass on joy and elation.

  • michael reynolds

    This minuscule study is funded in part by two USG agencies which are part of the drug war lobby. And previous studies, similarly tiny, have failed to control for binge drinking.

    Show me a long term, well-constructed, peer-reviewed study not funded by people with a vested interest. Until then this is vapor. (Hah!)

  • Show me a long term, well-constructed, peer-reviewed study not funded by people with a vested interest. Until then this is vapor.

    Yeah, that’s why I characterized the study as “interesting” rather than convincing, settled science, or what have you. If a study is long term, well-constructed, and peer-reviewed why does it matter who funds it? Isn’t the implication of that everybody will lie including the peers? Is that really true?

    I’m also not sure how long long-term would be in this context. I presume they would work under the hypothesis that the human brain stops developing at age 20, maybe a few years later.

  • PD Shaw

    Pot studies are rare because its illegal. Most of the studies come from the Netherlands, but IIRC legal compliance for minors is much higher their then you would expect in the U.S.

  • michael reynolds

    Many parts of my brain stopped developing at about 14. I didn’t start smoking pot till I was 19.

    Also, I’d like to see how the measure motivation. Is it possible this is just stoners breaking free of their programming long enough to think, “Whoa, dude! This test is like. . . stupid or whatever. I’m going to go watch cartoons.”

    Isn’t the implication of that everybody will lie including the peers? Is that really true?

    I certainly don’t know that to be true, but as a general rule people who pay for things get what they want. It wouldn’t take much fiddling with 20 test results to show a correlation.

  • That’s a factor that I think is lost on many Americans. We’re not really very much like the Brits, Dutch, or Germans with respect to legal compliance, generally. We’re more like the Italians or Greeks in that regard.

  • It wouldn’t take much fiddling with 20 test results to show a correlation.

    Which is why I agree that a much larger study would be useful.

  • Guarneri

    “Many parts of my brain stopped developing at about 14. ”

    Know thyself…………

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