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Pot-smoking young adults aren't doomed to psychosis just yet

March 1, 2010 |  5:05 pm

Pot Early, and then continued, use of marijuana does seem to be associated with an increased risk of psychosis and hallucinations, but allow us to quell some incipient panic.

Caveats, after all, are our specialty.

Previous studies had found a link (not necessarily a cause or effect) between cannabis use and psychosis. So researchers in Queensland, Australia, decided to investigate further and have now established what they consider a fairly strong connection between the length of marijuana use and the likelihood of psychosis in young adults.

The researchers even checked out pot use and psychosis symptoms among siblings just to make sure they haven't been missing some genetic or environmental factor. They don't seem to have been.

So pot use may well play some kind of role in what the researchers term "psychosis-related outcomes."

But, the researchers write in their conclusion: “The nature of the relationship between psychosis and cannabis use is by no means simple."

As they point out: "Those individuals who were vulnerable to psychosis (i.e., those who had isolated psychotic symptoms) were more likely to commence cannabis use, which could then subsequently contribute to an increased risk of conversion to a nonaffective psychotic disorder. In addition, analyses that incorporated adjustments for depressive and anxiety-related disorders led to a reduction in the strength of the association between cannabis use and psychosis-related outcomes. This suggests that depression and/or anxiety disorders may mediate or moderate the pathways between cannabis use and psychosis-related outcomes. We plan to further explore these issues in more detail in future studies."

This is fascinating and provocative stuff, especially as it pertains to young adults' still-developing brains. But the key word from the first paragraph is "associated."

So as for these headlines? "Long-term cannabis use can double risk of psychosis," "Study finds cannabis use is 'crazy-making'," "Teen pot smokers at high risk of mental illness," "Marijuana smoking teens prone to schizophrenia"... Perhaps some panic-quelling is in order.

Here's the full study, published online Monday in the Archives of General Psychiatry.

For a different look at marijuana, here's a recent L.A. Times story: UC studies find promise in medical marijuana

(Not cures, just promise.)

-- Tami Dennis

Credit: Daniel Karmann / EPA

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Comments (26)

"Perhaps some panic-quelling is in order." awesome.

Tami, out of the scores of news articles spinning this story in mainstream media that I've read, yours is the only one that didn't just bite the popular conclusion and instead popped the hood to see if cause and effect had been established.

Only one other article I found even mentioned this caution, and that was The Inquirer of the Philippines.

And of all those that said the article was available online at the Archives of General Psychology, where I could not for the life of my find it, yours was the only one that linked to the source.

This is the state of our media today. Sad, sad, sad. But thank you so much for your clear-headedness!


I wonder why blog postings are showing up as news these days?

If this were an article in a major news publication, it would be a prime example of biased journalism. No new facts, just conjecture, conjecture, conjecture... clearly Ms. Dennis is a pot smoker, or would like to be once its legal.

It's a simple concept: drugs kill brain cells. Lots of them. And they don't grow back. Brain damage, it other words. I cannot imagine a more likely cause of psychological problems than that.

Maybe not going crazy in the future? I'll smoke to that.

Isn't it just as likely that psychotics, or incipient psychotics, are self medicating with pot?

I just want to say "Thank you for tempering the media headlines" and thanks for the link to the actual study. You are the first (of ~20 articles) on this study to mention the depression/anxiety disorder aspect of the study.

if 3801 people were tested and 65 were diagnosed with psychosis that is a 0.017% possibility that the test subjects were wack jobs before smoking. could the cannabis have just brought out there true inner person

Finally, some rational logic amid the hype and hyperbole. I'll tell what makes me go crazy - America's insane pot laws. When will those who don't use or know anything about the stuff get out of the way of those who use it daily with no negative outcome? The last I noticed we are adults, not kids.

I have enjoyed Cannabis daily for forty two years so far, and now I have glaucoma. What are the odds I will be impressed by the hyperbolic news reports? Thanks for this fresh air.

And buying four lottery tickets quadruples the odds of winning the BIG one.


My problem is that this is not the first time that such a study was made out to link some kind of psychosis with marijuana use. The great thing about it is that this study and the others before it have been debunked one after the other.

This is definitely not the first time marijuana has been blamed for psychosis. Federal law enforcement, lead by racist Henry Anslinger, played that game during the early days of prohibition by claiming some 200 cases of murder were the result of marijuana use, most notably the case of Victor Licata.

If you can't guess by now, Victor Licata was indeed psychotic (schizophrenic) and he used marijuana.. go figure. Also, 198 cases were debunked and 2 were supposedly impossible to track down. In the case of Victor Licata, it was said his psychosis was hereditary being that his family was inbred and he had a family history of psychosis. Just as Henry Anslinger left out those facts, I have to wonder how many other facts were left out of the law enforcement inspired studies of today.

Federal law enforcement has not stopped, and will not stop, trying to tie psychosis, along with other ailments, with marijuana. It's all a part of the game they play to keep fear in the hearts of honest Americans. If it's possible that marijuana has negative effects, our government is doing a terrible job in pointing it out. All around the world, marijuana has been nothing less than beneficial.

The real question is, what's the connection between the US government and that study in Australia? Let's track down other debunked studies that claim negative health effects of marijuana. In 5000 years of recorded history, the side effects of marijuana use has been sleepiness and/or hunger. If marijuana has had such negative effects, we'd have known about it by now, not trot out debunked studies.

Drugs kill brain cells? Does marijuana specifically kill brain cells? Has that been proven by a independent, unbiased study? One that was not funded by the government to produce biased results that perpetuate the reefer-madness mentality that allows the law enforcement and the privatized prison system to continue reaping massive profits from incarcerating non-violent citizens (criminals?!) for using a natural substance responsibly that's been around since the beginning of time while also insuring that the paper, textile, and oil industries are not threatened by a renewable and efficient source of raw materials for their products?

Some drugs (prescription especially) kill livers and kidneys, which reduce the body's ability to process and remove harmful toxins that we absorb from food, water, and the environment in which we live. Could those harmful toxins that are building up in people's bodies cause any problems for them psychologically? Has THAT been proven in a study? Will it ever be considering the massive profits that the pharmaceutical companies stand to lose if such information were discovered and made available to the public? Could the travesty which is school lunch in the US have anything to do with some of the developmental problems some children face?

I wonder why 9 out of 10 comments these days on cannabis stories are insightful and intelligent while the remaining one is always some propaganda spewing hate message without merit. Clearly one of the commenters here is a Police Officer, owns stock in private prisons, or just wants to see every non-violent cannabis offender subjected to the horrors of the prison system to get the comeuppance they feel is deserved.

Good luck with that $60,000 a year police or prison guard job that you didn't have to invest a dime into an education to get so you could tow the line for the corporate behemoths that have all but eradicated decency and common sense from the american public so you could feel okay about going up against the majority with your generations-old lies and propaganda. Meanwhile I'm going to smoke a joint to take off some of the stress of having to pay back a $60,000 education while my entire industry has been shipped overseas to the lowest bidder in the ongoing eradication of the american middle class.

Prepare to live in a world where cannabis prohibition joins the ranks of slavery and other blunders of mankind as a very regrettable chapter in the book of history.

"drugs kill brain cells. Lots of them. And they don't grow back."

Cannabinoids promote embryonic and adult hippocampus neurogenesis

I smoked quite a bit of marijuana when I was young, and I am very healthy. Want to know what the marijuana laws are in your state? Go to There is lots of interesting stuff on that website.

As I read these comments, I find that it's 10-1 in favor of ending cannabis prohibition. Everywhere I go I find that it's about 60-40 for complete legalization. The prohibitionists still cling to the tired old arguments like the one comment here "It's a simple concept: drugs kill brain cells. Lots of them. And they don't grow back. " that isn't backed up by empirical data or legitimate research. I could not find a single study that indicated cannabis kills brain cells. And, no, I don't count DARE pamphlets as legitimate 'research'. Leaving the emotional debate behind, I believe that most normal people understand that the war on drugs is a complete failure. Contrary to the Partnership for a Drug Free America hysteria, we are not just about to win the war on drugs (as we have heard for decades), and, yes, we should quit throwing people in a cage because they wanted to consume cannabis in lieu of alcohol.

It's time to vote to end cannabis prohibition. I believe that votes are there. Isn't it time to let democracy act as it should and not let a few politicians dictate my non-violent actions because of their fear?


Ive smoked for 22 years straight, daily use, and I have a great career, a wonderful family, 2 daughters that think the world of me (or so Im told) and I couldnt be happier with the direction my life has gone. Im very healthy, I am 39 and am part of a local basketball league that meets for weekly games and practices. I am not on any medication for any mental illness, nor do I feel that my long term use has had any effect on my health what so ever. So I personally find it very hard to believe any of the claims that pot makes you crazy, its obviously propaganda geared toward people with no personal experience, and that's probably just to get more votes so they can further their agendas. I mean come on now, its been the most used drug since forever, and there hasn't been any indication other than a "new study" that shows pot does anything to anyone. I feel like the American people have become a tool to be used to advance others, and the corporate world is now allowed to buy our politicians, so common sense sees where were headed. This country has fallen apart and continues to deteriorate from the inside out.

I could use about a-hundred tacos right now...and a large pizza

Ive been blazing for 10 years. It helps me with a variety of different ailments. I love the fact that everyone knows now, that anything negative about marijuana is 99% of the time misinformation and propaganda by someone with a specific moral or political agenda. And guess what? Smoking herb is not immoral; and I would choose it over your precious cigarettes, alcohol, pills, or guns ANY time or day of the week.

So guess what? You can't believe all the lies that you hear when you grow up. You can't believe everything the politicians/government/teachers tell you about weed. At the end of the day, it's all about making decisions for yourself and making the right ones. I know now that marijuana was grossly exaggerated for the benefit of politicians/govt/police officers etc. all to further the linings of their pockets and their views they want to instill upon everyone.

Too bad it's not going their way anymore.

John K, how can you make such a claim. A general "drugs kill brain cells" ist just nonsens. Alcohol does damage brain cells (yet you have enough cells to spare some if you drink with moderation). Nicotine, while having negative consequences, does not kill brain cells.

Cannabis doesn't kill brain cells either. Never ever has any study resulted in such a finding. In fact, cannabis is proven to cause regrowth of nerve tissue, possibly also of connections between brain cells.

After a tumor a major muscle was removed from my leg and part of the leg was left without nerve and thus without sense. I started using cannabis after that and part of sense has returned (even though my doctor told me that part of my leg would remain without sense forever).

Some of the brightest minds, e.g. physics nobel prize winner Richard Feynmann, have been (heavy) cannabis users. This alone proves that cannabis cannot "kill" brain cells.

Yes.... Marijuana kills brain cells..... and when you blow up people you go to heaven and get 70 virgins....
I wonder when people will start thinking by themselves.

John K , marijuana does not kill braincells have you ever used google ? and you say they don't grow back ? well even if that is true you should know that we have "BILLIONS" of braincells that will never be used.

I hate to point this out, L.A. Times, but you're not quoting the research accurately. The study does not evaluate the how long cannabis has been used, but only how long it has been since cannabis was used for the FIRST time. The authors state:

“The main predictor variable did not capture cumulative exposure to cannabis. It is feasible that some cohort members may have started cannabis use at a relatively young age and then stopped. These subjects would have been allocated the same duration since first cannabis use as those with early and persistent usage.”

In other words, a person who used cannabis only one time, six years ago, was counted as a longer-term user than someone who uses cannabis every day but who started only three years ago. Failure to account for actual length of use or quantity of use, rather than merely passage of time since first use, significantly undermines the value of this research.

The March 2010 Cannabis paper in Archives of General Psychiatry is at

Legalization. Taxation. Regulation.

Since the vote to legalize cannabis is coming up in November 2010, the "old" establishment has decided to reelect Harry Anslinger as their spokesperson.
Actually the street word for this temporary condition is called "bugging out" and not psychosis. When I drink too much I pass out but when I smoke to much I (can) bug out. It's marijuana's way of saying to me "Ok Doctor I think you have had enough". This experience is only temporary; in fact its remedy is the same as someone who is having a panic attack, breath into a paper bag and in 30 seconds you are back to normal/boring again!

Keep in mind there are no current reports of the masses being admitted into mental hospitals considering how many people have been reported by media who use cannabis.
Quite the contrary, most serious alcoholics end up on the street, dead or abusing the people they call their family.
We can't take alcohol away from the masses just because day after day, month after month, year after year it is directly related to road carnage, wife beaters, child abusers, political embarrassment, police brutality, theft, rape, and just so much more (Google alcohol related crimes and accidents).
Note: The police are looking at a huge reduction in work force and they will say, quote, lie or conspire to keep their jobs, all the while the rest of us are out of work and our taxes are paying for them to buy things and take their girlfriends out to dinner tonight! We will not tolerate this anymore and come November we will leave our pot closets, show our faces to the world and light up together once and for all as we celebrate our personal freedom long, long overdue.

Self reported hearsay evidence masquerading as "science" WOW our tax dollars at work!!!

It is closer to bad maths(statistics) than true empirical science.

Questions that were NOT asked in the"study"

1. Which of the 1500+ known varieties of Cannabis were consumed?
2. How was it grown, organically or chemically?
3. Was the Cannabis "tainted" by other substances, ie chemical fertilisers, or Insecticides?
4 How was it consumed?
5 Was it mixed with other substances that have been shown to cause psychosis ie Alcohol, pharmaceuticals, or other unlicensed medicines?

Until those questions are asked in any data gathering exercise, to conclude that cannabis "caused" anything is is just insanity and certainly not "Science"

JohnK if cannabis causes brain cell death why has the US Health department patented Cannabinoids as Neuro-Protectants?

There is a theory that cannabis causes psychosis in those that DON"T use it. This study does seem to add more weight to that theory.

Living in a world of fantasy and denying reality is psychosis.
Preferring to believe in myths and fears even when confronted with truth is mental illness.
Propaganda for war is ILLEGAL under international law and the "War on (some) Drugs" has been formally and officially declared by Governments the world over.
When are we going to charge these people for promoting Propaganda for their war.

Several studies have shown that the percentage of the population developing psychosis has remained stable over the past many decades, whereas during the same time period the percentage of the population using cannabis has greatly increased. Therefore, one can logically conclude that cannabis use does not provoke or lead to psychosis at all.



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