Brain researcher cautions against suggestions cannabis causes schizophrenia

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Cannabis indica. Credit: Wikipedia
(Medical Xpress)—Matthew Hill, of the University of Calgary's Hotchkiss Brain Institute has published a Perspective piece in the journal Nature voicing his concerns about other academics and journalists who suggest that cannabis use causes schizophrenia. He points out that there is little evidence of such a connection and suggests that there is actually evidence that cannabis use does not cause the mental disorder.

Cannabis use has been in the news a lot of late, particularly in the U.S. where some states have made it legal to smoke marijuana—the common name for cannabis. But because it is a hot-button topic, some, particularly those opposed to its use, have taken to looking for reasons to stop the movement—and one of those arguments is that it causes schizophrenia. The problem with that, as Hill notes, is that no one has ever proved it to be true. He notes that it is almost certainly not true, noting that the incidence of schizophrenia has not gone up since cannabis use in Europe and the U.S. rose sharply after the 1960's. Also, he notes, countries where a large part of the population use cannabis do not have a higher percentage of than countries where few if any people use the drug. Hill does point out that it appears that cannabis use might bring on schizophrenia earlier for those who are going to develop the disorder anyway.

Hill had an article published last year in the Journal of Psychiatry & Neuroscience, called "Clearing the smoke: What do we know about adolescent cannabis use and schizophrenia?" in which he outlined studies that have been conducted to determine if cannabis does indeed cause schizophrenia—the first of which was conducted back in 1987 in Sweden, and did find such an association—army conscripts who used cannabis were found to have a higher incidence of schizophrenia. It was this study that has led to the common belief today that the drug causes the mental illness. But, as Hill notes, what the study actually found was that high doses of tetrahydrocannabinol—the psychoactive component of cannabis, can cause acute psychosis—but only for a short period of time. The researchers back then assumed the condition could be permanent and lead to schizophrenia and thereby made their pronouncement. He notes that no other study has come to the same conclusion.

There have been other studies conducted but not cited by Hill, most prominently one done by a team at Harvard University recently—all have led to the same conclusion—that use does not cause —but still as Hill notes, the notion continues. He cautions against those who wish to incite and suggests that careful evidence based arguments be used when it comes to making policy.


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More information: Perspective: Be clear about the real risks, Nature 525, S14 (24 September 2015) DOI: 10.1038/525S14a

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Sep 24, 2015
We do not get the "high" from delta-9 tetrahydrocannabinol. We get it from the metabolic products from action by the liver, which are the major psychoactive actors.

And, with generations of use, we should know for sure if it causes problems by now. Is this a politically-motivated stunt?

Sep 24, 2015
This falls clearly in to the category of "policy-led evidence".

Most people who decide that smoking pot is a bad thing make that decision on moral grounds, chemical fun is not a good thing generally. OK they have a point, and excessive usage should be dealt with like say alcoholism. But it is not criminal activity - which I would define as actions intended to harm others.

Sep 24, 2015
I see I got a one from Ira. Does he have any newer information than mine? I still have the report from 1971.

I think his issue is personal, not scientific.

The liver process explains the reverse tolerance of cannabis users. At first, many folk get nothing from it, until their livers get used to putting out the metabolizing substances, creating the metabolite which is most psychoactive.

Sep 24, 2015
Using pot allows you to access parts of your brain you normally only use subconsciously. This could open doors you may not be able to close, in theory, if are already predisposed. But only if you really try a lot and smoke constantly for years and years without seeking nominal treatment.

Sep 24, 2015
"Using pot allows you to access parts of your brain you normally only use subconsciously"
------------------------------

Really? We have normal receptors for those endorphins, so the purpose is natural. Why would you think it lets use some part of the brain we do not normally use?

Sep 27, 2015
Gkam, if it was processed by liver it would take longer to hit you.
The liver weakens drug effects, that's why people shoot up heroin and even alcohol, gets that pesky liver out of the way

Sep 27, 2015
Steve, it was not my study.

Want a copy?

Oct 02, 2015
gkam,
Many of my undergraduate students come into class with this misconception that it is the metabolites that are actually the psychoactive compounds and not THC. Yes, some are psychoactive, however, THC is the primary compound that causes the immediate high due to its high affinity for the receptors in the brain.
I would love to obtain a copy of the study you are referencing. Can you please share? I think it may be one that has since been shown to be incorrect, similar to many of the early papers published prior to the discovery of the cannabinoid receptors in the brain.
Thanks!

Oct 02, 2015
Sure. How to get it to you? I photocopied it from a very old Psychology Today.


Oct 02, 2015
SciProf, I am going to cut out of these fora. I was warned about them, full of cowardly snipers hiding behind pseudonyms and cut-outs. They are the treponema pallidum of the internet, contaminating all they can reach.

Find a way to get the report by email, perhaps with a temporary gmail account or equivalent.

Oct 02, 2015
What's the title of article, author(s), journal edition, and year for the journal article? I should have access to that journal through the university if 1988 - present or through interlibrary loan if earlier.
Thank you!

Oct 02, 2015
Psychology Today, May, 1971, volume 4 number 12 starting on page 36.

Solomon H. Snyder and Charles T. Tart, and T. George Harris.


Oct 02, 2015
Thanks for the info. Does the article that begins on pg 36 have a title?

Oct 02, 2015
Thanks gkam! This will be invaluable for class discussion. Is the following the correct reference?
Snyder, S. H. (1971). WORK WITH MARIJUANA. 1. EFFECTS. Psychology Today, 4(12), 37.

Oct 02, 2015
Yes, and "II Sensations" follow on page 41, . . but we already know that part.

The introduction is by Harris, called Politics of the Interior, on page 36.

I am george@kamburoff.com if you trust me with your email address, I'll send the pdf's, or can mail you the originals.

It is refreshing to finally find another real professional here, in the sea of gamers. There are a few.

Oct 02, 2015
SciProf, to illustrate the condition of this forum, look to see how you were rated as a "one", by someone who got upset when he found out I am a real person, and not a gamer. He now "punishes" you for discussing the issue with me.

It's like trying to discuss serious science in a playground of kids screaming insults.

Oct 02, 2015
gkam,
Agreed. I typically avoid discussions in forums open to the general public, but you mentioned sharing a particular reference/study that points to why so many students get particular questions about cannabis mechanisms wrong on the test.
If interested in more modern papers, I suggest 2004 or later review papers by Allyn Howlett (AC Howlett). She is a well respected cannabinoid researcher in the pharmacology field. The science articles are often very detailed on mechanism and pharmacology-specific jargon, but the intro and conclusions sections often boil it down pretty well. Unfortunately not many scientists can easily distill their research down into easily understandable terms, so misconceptions based on earlier research or on the media's misunderstanding of current scientific publications are quite common, especially in neuropharmacology.
Cheers

Oct 02, 2015
It's like trying to discuss serious science in a playground of kids screaming insults.


Well golly gee wiz, glam-Skippy got the new (imaginary) friend to play with. Cher, I told you that you were not unique, after all you been through you still think you got a trick that hasn't been tried by all the others just like you? Dozens and dozens of times? You should really be hoping that the Otto-Skippy doesn't find this one, he will have the turkey choot with this one.

Oh yeah, I almost forget. So besides being a liar, and silly sloganeering-Skippy, now you have taken up cheating too? In America you are supposed to vote the one time and move on. Setting up all those puppet-Skippys to vote is wrong. And thinking that it was smart and sneaky was really stupid like the other things you try. What? You think just because YOU can only see how peoples is voting recently that NOBODY can go and have the lookie-loo further back than you can?

Oct 02, 2015
Ira, I have only one account here, one name, which I made public unlike you. If others find you shallow, they are exhibiting good sense.

I suggest you look up the references he left us, and learn something.

Oct 02, 2015
Ira, I have only one account here, one name, which I made public unlike you. If others find you shallow, they are exhibiting good sense..


Otto-Skippy was right. Your type lies even when caught red-handed. glam-Skippy, you are a sad little old man who uses the interweb to "be" all the things you wish you "were". Cher, no matter how old you are, you can still do things that are accomplishments, try a hobby or study something without needing to be the instant expert. Pretending won't ever give any real satisfactions. You really don't believe that we have seen "you" dozens of times before here?

Puppets are tolerated here, when you get the boot-a-roo. Using multiple puppets to vote with is going to far.

So KNOCK IT OFF SKIPPY, AND PUT YOUR SILLY LOOKING POINTY CAP ON AND SIT DOWN!

Yeah, that's right, the one with the moons and stars on him that you picked out so everybody would recognize you while you were still a block away.

Oct 02, 2015
The article says it was probably not marijuana which did that damage to your head, Ira, and I think it was swamp rot. But I would rather not just exchange nasty insults with you shallow folk. Did you read the references he gave us?

Do you have anything important to say about the issue?

Oct 02, 2015
Do you have anything important to say about the issue?


Yeah, I got something important to say. When your lawyers get done giving otto-Skippy the big trouble, I'm going to send them over to you for telling the another GREAT BIG LIE. This time you defameded and liabilited and slandered me some too. I do not take drugs, and never have except for four or three times when I was the teenager me. And I do not even drink alcohol.

Oct 02, 2015
This is silly. I say something, and you try to find something in it to which you can take offense or can ridicule, or can make some reference to me personally.

It really does say more about you than about me, Ira.

Oct 02, 2015
So Uncle Ira, who are the gkam puppets so I can give an email to phys.org?

SciProf, and...?

Oct 02, 2015
So Uncle Ira, who are the gkam puppets so I can give an email to phys.org?

SciProf, and...?


They are already on to them. How you think I found out about them? Funny think about it though, all glam-Skippy been spending a lot time voting lately, all for not anything. The nice peoples at physorg stopped those votes from getting added in on the BIG score card.

Do you know why he got the boot-a-roo from the Walmart? He is too ashamed to tell me about it and I asked five or four times.

Oct 03, 2015
Well Ira, the only thing I've seen a reference for with his posts is about weed. Even then he got it wrong ! Liver products pheshaw!
I'll go with the odds and say he got too stoned and got lost in Walmart. Burned a flag? Potty on the floor?

Oct 03, 2015
Well golly gee wiz, glam-Skippy got the new (imaginary) friend to play with. Cher, I told you that you were not unique, after all you been through you still think you got a trick that hasn't been tried by all the others just like you? Dozens and dozens of times?
Yeah zephyr used to talk to himself a lot. So did pussytard.
Ira, I have only one account here, one name, which I made public
-and which you thoroughly trashed by lying, cheating, and fabricating.

So you can understand when people here suspect you of talking to yourself.

Does the good prof know that you lied about your MS?
http://phys.org/n...ack.html

-Probably. He's probably you.

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