Trending >

Childhood marijuana use can affect brain function and lower IQ: study

Childhood marijuana use

Childhood marijuana useA new study out of Western University and the Robarts Research Institute in London, Ontario, has found that childhood marijuana use can detrimentally affect brain functioning and potentially lower IQ.

Researchers were looking into the effects of frequent marijuana use on brain development and mood disorders in youth aged 16 to 23 and found not only that marijuana use did not alleviate depressive symptoms but that it had a deleterious effect on brain functioning in a number of areas related to visuo-spatial processing, memory, self-referential activity and reward processing.

“These findings suggest that using marijuana does not correct the brain abnormalities or symptoms of depression and using it from an early age may have an abnormal effect not only on brain function, but also on IQ,” says Dr. Elizabeth Osuch, of the Lawson Health Research Institute and the Dr. Joseph Rea Chair in Mood Disorders at the Schulich School of Medicine & Dentistry at Western University.

The relationship between marijuana use and both cognitive impairment and mental illness has been the subject of much investigation over the past decade, with growing evidence suggesting a link between marijuana use and the risk of psychiatric disorders ranging from schizophrenia to anxiety and depression. The risks to youth have been a particular focus, including one 11-year study of childhood marijuana users which concluded that early marijuana use was associated with declining educational achievement, lower income, greater unemployment, declining relationship satisfaction and declining life satisfaction.

The current study recruited 74 youth aged 16 to 23 and divided them into four groups depending on both marijuana use (frequent or infrequent) and mood disorder (those with depression and those without). The four groups were put through a range of psychiatric, cognitive and IQ tests, along with brain scans to test for brain functioning.

The study found that perhaps contrary to the perceived wisdom, frequent marijuana use did not correct the brain function deficits associated with depression and in some cases made them worse.

“Many youth in our program use marijuana heavily and, despite past research, believe it improves their psychiatric conditions because it makes them feel better momentarily,” says Dr. Osuch, “For this reason, we decided to study the effects of marijuana and depression on psychiatric symptoms, brain function and cognitive function.”

The research was published in the journal Acta Psychiatrica Scandinavica.

Researchers have recently put another widely assumed attribute of marijuana use to the test, namely, that smoking week improves creativity. The study from Leiden University in the Netherlands found that frequent cannabis users were less capable than others of brainstorming, a process commonly linked to creative performance.

In addition, researchers found that the processes used to monitor one’s activity for mistakes was also negatively affected by cannabis use.

More Cantech Science

We Hate Paywalls Too!

At Cantech Letter we prize independent journalism like you do. And we don't care for paywalls and popups and all that noise That's why we need your support. If you value getting your daily information from the experts, won't you help us? No donation is too small.

Make a one-time or recurring donation

About The Author /

Cantech Letter founder and editor Nick Waddell has lived in five Canadian provinces and is proud of his country's often overlooked contributions to the world of science and technology. Waddell takes a regular shift on the Canadian media circuit, making appearances on CTV, CBC and BNN, and contributing to publications such as Canadian Business and Business Insider.
insta twitter facebook


  1. The reefer madness continues. Trotting out an extremely flawed anecdotal study as proper evidence of anything just shows how scared the idiots out there are of cannabis. The “Dr.” in the article above doesn’t even know that the substance is cannabis…marijuana is a derogatory slang term. Like saying nigger, the biased discrimination is disgusting.

  2. It is equally logical to argue that declining educational achievement, lower income, greater unemployment, declining relationship satisfaction and declining life satisfaction are associated with early marijuana use.

  3. Birth control pills cause depression. How many of these kids were on the pill during the study?

  4. so what are the effects of the development of the brain on a child that has 6 or more epileptic seizures a day? I have seen that in action, and big pharma drugs did nothing. No thriving, no independent thinking at all………..

  5. You logic is flawed, I’ve been a daily toker for the past 5 years and I’m an executive at a fortune 500 company but these “Paid for by government” testing always seems to point us in the direction that this is bad but yet more and more countries are legalizing it, doesn’t that sound counter production or it sounds like the public was fed this BS story about a drug that would have made Mexico rich is the worst thing next to Hilter.
    When are people going to realize 99.999% of anything on the news is pure Bullshit.

  6. What about childhood alcohol use? What health effects are there on children who drink daily?
    The hypocrisy is maddening!

  7. Better than Harpercrite righties who cannot get any supporters because they are all dickheads.

  8. Obviously, the government does not give funding to find the positive affects of Cannabis, and only the negative. The media eats this up like they are Hash-Brownies..
    You can’t scare the masses when you have the educated few.

  9. Birth control pills, millions of women take them.. Millions of mg get expelled into the toilet, and back into our water system..
    That should be an article there.. Extra estrogen in our water supply.

  10. low IQ is not doing your own research and relying on Fox news and Donald Trump for your information..
    get with the program..

  11. Amazing we just learned that the birth control pill can cause the exact same symptoms of depression, bipolar and schizophrenia. Are doctors going to stop prescribing it?.

  12. Kudos to you bud. But my statement was not designed to imply that the educated and successful cannot be so while enjoying the weed. I was simply pointing out that the manner in which the causality was suggested was so unscientific that it could actually be argued equally well in the opposite direction, making the connection meaningless.

  13. The processing of natural languages somehow gets hampered after using modafinil for a while. You will mark, that after a day of work, the normal day to day chitchat seems to be incomprehensible. I am a programmer and it feels like the parser in my head is failing. I don’t have a source for this, but it is reported by more modafinil users. It could be fatigue of course. If you really wanna try it – there is the online store with international licence https://modafinilxl.com/ – only 2$ for a pill ( 33$ in US pharmacy stores)
    If you don’t watch out , you get enough sleep, you will do some damage to your brain.
    Your mouth will be more dry, which can lead to mouth sores and worse.
    And it touches a lot of systems, which is never free. So if you stop after a while, you can feel somewhat down for some time. Modafinil increases the amount of dopamine in your brain. (
    And then you have that skin disease, which can have some pretty grim longterm effects.
    You can trap yourself into the stimulant trap, which goes a bit like this:
    You slowly build up more obligations, because you are more motivated then the rest. At a certain moment, you want to switch back to normal, but, now you have two lives, one which is brought by modafinil, the other is what you can naturally lift. Stepping outside the stimulant trap can be difficult.
    And we don’t know modafinil very well, the longterm effects can be anything.
    Just don’t do it every day, just use it when you need it. Tolerance will eventually develop and taken more and more will make the side effects stronger,

  14. “Studies” like these are absolute garbage. Kids (under 18) shouldn’t be smoking copious amounts of cannabis but even if they did, it isn’t going to lower their IQ lol! IIRC there was a study done in Jamaica which had the complete opposite effect.

Leave a Reply