Changes in schizophrenia diagnoses associated with cannabis use disorder
120 comments
·February 5, 2025a_cardboard_box
mlyle
Maybe not even worse.
This is looking at what fraction of schizophrenia cases had significant cannabis use.
If more people use cannabis, there will be more of these cases, even if there's no causal link.
throwawaymaths
causality might go the other way. having had a friend that was so, i wonder if a significant fraction of schizophrenics use cannabis to be functional in society
appstorelottery
Cannabis misuse appears linked to a larger share of schizophrenia cases as I understand it.
ty6853
Schizophrenics love to smoke. My unscientific guess is something like 80% smoke a nicotine product or weed.
anjel
Scott Alexander wrote an article [0] on the mild antipsychotic effects of nicotine as the reason why such a high proportion of people battling psychosis smoke cigarettes.
[0] https://slatestarcodex.com/2016/01/11/schizophrenia-no-smoki...
cjbgkagh
There is the dopamine hypothesis for schizophrenia and new research suggest serotonin also plays a role. Nicotine increases the dopamine in the brain so it sounds like to me smoking would be a form of self medicating.
zxexz
Not sure why you're being downvoted. The link is well-documented. I'm pretty certain the only controversies here are in causality.
bb123
I'm not really surprised by this finding. My anecdotal experience has been that pretty much everyone knows a friend or a friend of a friend who smoked too much pot and had their life go off the rails. It is pretty clear to me that it is not a harmless herb despite that being the commonly held belief on places like Reddit.
Retric
Implying causality there is often misplaced. I’ve noticed some people smoke more after things start to fall apart from issues they have no control over, just as others binge eat when stressed.
It’s not a helpful coping mechanism, but there’s a reason double blind studies are considered so important. Untangling complex mechanisms especially when they have feedback in both directions is inherently difficult.
RhysU
Some drunks drink more as they approach bottom. Is it the booze? Is it being the sort of person who becomes a drunk? Does it matter? More booze ain't helping.
You're really going to call for a double blind study here checking if excessive cannabis is bad for people conditional on their lives falling apart? How do you propose to get that past an ethics board?
dgacmu
It doesn't matter because you can't do a double blind study on pot. Double blind -> the patient doesn't know what they got. "Hmm did I get cannabis or oregano? I just can't tell". :)
You can still do a randomized trial and that's the one that wouldn't pass the IRB.
Retric
I’m not calling for double blind study here, I’m not even sure how that would be possible.
Sometimes we’re stuck with “I don’t know” and recognizing that is IMO important.
bawolff
> Some drunks drink more as they approach bottom. Is it the booze? Is it being the sort of person who becomes a drunk? Does it matter? More booze ain't helping.
I mean, it kind of does. If you want to design intervention, it helps to know which causes the other to a greater degree.
Aurornis
> My anecdotal experience has been that pretty much everyone knows a friend or a friend of a friend who smoked too much pot and had their life go off the rails
Sadly, I’m seeing a new trend of people taking too many psychedelics and going off the rails.
The way they’re being pushed as cure-alls for depression is getting scary.
One of my friends developed severe problems after following the microdosing trend. It developed slowly over a long period of time, but he thought he was okay because he was following one of those protocols from one of the biggest microdosing experts.
Rendello
Syd Barrett and Peter Green always come to mind, as well as some local examples who wander the streets aimlessly. The appeal of psychedelics for depression –Or rather, what I thought was depression– tempted a younger me, until I observed that the people I knew who swore by it were quite strange and not exactly exemplars of good mental health.
Loughla
Pot is one of those things that makes things worse if they're already going badly.
Like alcohol or opiates will make your good life bad if you fuck too hard with them.
Pot, in my experience, won't really ruin your life unless you're already on that path.
My thing is that it's mostly harmless, but the problem with it is that young people can become complacent with it. It won't necessarily ruin your life, but you'll be content to sit and veg your life away. So not bad, but not good.
bongodongobob
I don't think I do. I do know a lot who have fucked their lives with alcohol and opiates though.
HackerThemAll
Drinking too much coffee or even water can kill you. Too much sugar can kill you (albeit not too quickly). Obsessive eating or shopping can derail your life pretty quickly. Obsessive use of social media can induce depression. Some people kill themselves because of what they read or see in social media.
So it's not the legalization at fault, it's people who are overdosing any stuff that's available to them. Casual smoking a weed once a week won't harm you that much.
LoganDark
While I also have anecdotal experience that suggests early-life cannabis abuse can lead to short-term memory loss, I have not seen any evidence that it leads to much else. I would imagine that people with a genetic predisposition to schizophrenia would only not have it by chance, and that altering their brain with pretty much anything can risk upsetting that balance. Doesn't matter if it's weed, LSD, opioids... SSRIs, stimulants...
Aurornis
> that altering their brain with pretty much anything can risk upsetting that balance. Doesn't matter if it's weed, LSD, opioids... SSRIs, stimulants...
Of course it matters. Different drugs and doses have completely different effects on the brain.
Trying to to equate different drugs and claim they’re all similarly risky goes completely against everything we know.
throw__away7391
Conspiracy theories. Every heavy pot smoker I know has ended up believing in multiple conspiracy theories. Back in the day before YouTube my friends were burning DVDs of 9-11 Truther documentaries, a chick I dated became obsessed with UFOs and alien abductions, a close family member began to believe they had found a way to develop psychic powers, and the boomers who got their medical marijuana cards deserve their own category based on the number of right wing conspiracy theories they repost on Facebook. The only exception I can think of got heavily into sports betting with a similar level of obsession and belief that they had deep insights that escaped everyone else.
I suspect that it triggers part of your brain that rewards you for making connections or something like that.
ryandvm
Or people that are willing to engage in counter culture or illegal activities are more likely to reject cultural doctrine.
stevenAthompson
My life experience matches yours perfectly. I would love to see a study.
Maybe one that examines the rise of the alt-right and it's relation to legalization. The timing seems correlated.
AnthonBerg
That seems to be the case. In the literature it’s studied under the concept of aberrant salience. A Google Scholar search turns up seemingly interesting (salient, haha) papers: https://scholar.google.com/scholar?q=cannabis%20salience&btn...
From one of the papers: “the Aberrant Salience (AS) construct […] refers to an excess of attribution of meaning to stimuli that are otherwise regarded as neutral, thereby transform them into adverse, dangerous, or mysterious entities. This leads the patient to engage in aberrant and consequently incorrect interpretative efforts concerning the normal perception of reality and its relationship with our analytical abilities. AS appears to play a significant role in the onset and perpetuation of psychotic disorders. The internal conflict arising from aberrant attributions of significance leads to delusional thoughts, ultimately culminating in the establishment of a self-sustaining psychosis.” — https://www.frontiersin.org/articles/10.3389/fpsyt.2023.1343...
t0lo
That sounds... pretty fun
nick__m
According to what i remember reading in 2010 (maybe the science has changed in the last fifteen years but I doubt it)
People with the Val158Met COMT polymorphism are more susceptible to develop schizophrenia sooner if they are exposed to cannabis. And that genetic mutation make them more successible to have cannabis use disorder. Knowing that I don't understand the question that this study is attempting to answer.
HiroshiSan
A lot of people like to pretend that smoking weed is harmless.
I support legalization but from my personal experience, I’ve suffered psychosis twice after smoking weed, and that’s enough for me.
barnabyjones
I agree it can cause those effects but it always seemed to me that the weed is just causing sleep deprivation which eventually leads to psychosis. IME it's not much different from alcohol in that way, they both disturb REM sleep so you end up deprived with daily use. It's just more apparent with weed because you don't get the hangover effects, so it's easy to overuse.
monero-xmr
It is incredible that the slightest increase in any cancer associated with alcohol is immediately trumpeted, but no matter how much research shows marijuana has dangers, the stoners always brush it off.
Just accept the risks and live your life. Nothing is without risk. Drink your beer and smoke your joint, why bother living if you aren’t going to enjoy yourself
redeux
There are people who minimize risks of both pot and alcohol but most of the adults I speak to that use marijuana understand the risks.
someothherguyy
Plenty do those things out of desperation, disease, and despair. In some, that leads to generations of harm. To many, the risks aren't even part of the equation.
codr7
Alcohol is poison, really.
Cannabis is one of the least toxic substances available.
They have absolutely nothing in common.
aurareturn
Schizophrenia symptoms:
Hallucinations (e.g., hearing voices), delusions (e.g., believing one has special powers), disorganized speech and behavior, reduced emotional expression, lack of motivation, withdrawal from social interactions, problems with attention, memory, and decision-making
I highly recommend r/leaves to read other people's stories trying or wanting to quit weed.
Edit: For those wondering, after being sober for 1.5 years, I'm pretty much back to my old self. My memory took a while to come back but it's drastically better than it was when I first quit. I feel much more motivated in life. My relationships with family and friends are better and so is my physical health. I was smoking about 0.5g - 2g/day for 1.5 years.
highasfcuk
Nearly all are all symptoms of depression, delusions with manic depression. Nearly all are symptoms of being stoned too.
It's unlikely you were experiencing schizophrenia unless you were actually hearing voices, thinking that you were a "Targeted Invididual", things like that.
aurareturn
I was merely going by the symptoms after a simple google search. I wasn't hearing voices.
I never got to that point though I believe I would have eventually had I continued. The weed I had access to were of questionably quality and wasn't professionally grown like the dispensary ones. I also never tried THC oil or other super strong weed products - which I read can drastically increase schizophrenia.
morpheos137
I have used weed a number of times. I also consider myself a schizoid personality disorder person. Supposedly that is on the very mild end of Schizophrenia. I have never found it to lead to psychosis or anxiety in myself.
All it does for me is make me feel relaxed and euphoric. If I use a lot I feel more relaxed and euphoric.
I am normally a person who is very detached from what people call a sense of self.
I believe this immunizes me from the anxiety many feel when losing self control under substances.
I do find annoying how many "pot heads" seem to think that weed is a panacea rather than a pacifier with some risks for some people.
Although the effects are different I would very much consider it akin to alcohol or an opiate.
If you have problems it will likely make them harder to deal with.
If you are just looking to relax or escape and are not prone to anxiety then it is effective but in my experience not much different from alcohol or opiates except less physical harms or potential for physical addiction.
I agree with the posters that for many if not most people, including myself, weed can give the illusion of some special insights or special connections to others but it is important to recognize just that, that this is an illusion, that our subjective feelings at any given time do not necessarily correspond to objective reality.
It is shocking to me how many people in all kinds of areas of life think that because they feel something is true it must be true or important or relevant.
Weed evidently makes many weed users feel it is a wonder drug, thus propagating and sustaining the mind virus.
I think it should be legal.
I also think if you want to be successful in life habitual use is ill-advised.
I can certainly see how for anxious, over thinking, controlling types it could lead to psychosis, like any number of other things, even including ideas. However I believe this effect is more due to a pre-existing neurotic psychology of the specific user rather than an intrinsic property of the drug.
But regardless it's not harmless.
Additionally the long term effects are not well known.
LoganDark
I've tried cannabis a few times but I couldn't get it to do nearly anything at all. I've tried a few different kinds and also tried THC tincture, but could never get anything to happen other than some slight dissociation. Is that "stoned"? Is my brain just not receptive to it or something?
portaouflop
Every human brain is different, some smoke a lot of pot and develop serious mental issues— others smoke a ton for years and you don’t notice any change.
The problem imo with this kinds of studies is that people can’t take the nuance and rather see it as “weed = bad” or some other binary outcome.
Imo all drugs have a potential to be dangerous — all adults should have free agency what they do with their bodies.
Sure cannabis, alcohol or mushrooms are dangerous, but I would argue a society that makes their use completely illegal without nuance is not a free society
pea
It's very interesting. I am extremely sensitive to THC, in a way I am not to any other drugs. A small amount (5mg) gives me full on disassociation/derealization, very anxious thoughts, etc.
I always wondered if other people had the same experience of THC as I did, but responded _psychologically_ differently to me, or if it was a _physiologically_ different experience. It was very confusing during high school.
Bizarrely I've found this react to weed much more common in the UK than California. There would be no reason for that to be true, though.
Aurornis
> I am extremely sensitive to THC, in a way I am not to any other drugs. A small amount (5mg)
5mg is not a small amount for someone without tolerance.
An old chemistry major college friend went into the THC industry. His company was very careful about production, measurement, and labeling.
He said it was very common for people to tell him that they needed some high number of milligrams to feel anything, then they’d ask him for samples from his company. They’d take what they thought was their normal dose and get completely knocked out.
A lot of products are (or were in the past) apparently very optimistic about their THC content. 5mg is actually a significant dose for most people without tolerance.
LoganDark
> I always wondered if other people had the same experience of THC as I did, but responded _psychologically_ differently to me, or if it was a _physiologically_ different experience. It was very confusing during high school.
I wonder this too. Maybe, say, non-autistic people would interpret differently what I see as mild dissociation, and experience all of the... whatever the fuck THC is supposed to do to Normal People. Or so the theory goes.
ZYbCRq22HbJ2y7
> A small amount (5mg) gives me full on disassociation/derealization, very anxious thoughts, etc
It is pretty common for people to have panic attacks while using cannabis. Those can be the symptoms of a panic attack.
> There would be no reason for that to be true, though.
Concentration, cannabinoid composition, adulteration (analogues, enhancement, etc), contamination (heavy metals, pesticides, mold, environmental or biotic toxins) are a few things that come to mind.
rufus_foreman
That was my experience also. I would smoke with my stoner friends, and it didn't seem to do much. I would think maybe I wasn't inhaling enough or something but then I would look in the mirror and my eyes were blood red.
I think it's just an expectations thing. I was doing max doses of acid for a long time before I ever used marijuana, and that ain't "some slight dissociation". On acid, you would watch the houses across the street stand up, join hands, and dance around in circles. Pot just didn't move the needle.
Perenti
I knew a few people when I was young (20s) that "pot does nothing" to them. Then one day they took a toke from a joint going round and were totally munged.
I've seen it a few times, and I have no idea why it's like that for some people.
Havoc
Sounds like a dosage situation. A lot of the tincture stuff just isn’t all that strong.
Effect wise - I mostly notice it in sensation of time. Two hours feels like four. And it’s not smooth flow of time - almost skips occasionally.
djkoolaide
People have this strange concept that weed is supposed to make you see rainbows and stuff lol. I'd say your experience is about normal.
LoganDark
I've never heard about rainbows and stuff, at least not for weed. I've heard for some people it increases their depth perception to potentially painful levels, I've heard for some people it makes them feel like they can see with their eyes closed, I've heard for some people it makes daydreams more vivid/accessible, I've heard for some people it makes things feel/appear funnier than they actually are... but for me it's just some slight dissociation, which doesn't exactly manifest as a particularly interesting or impaired experience since I experience dissociation all the time just naturally (thanks to my dissociative disorder).
iammrpayments
It just made me feel 0 anxiety, but I thought the experience was not good enough to justify breaking the law
codr7
The law is broken, you couldn't break it more if you tried.
csomar
Your brain is not receptive. This could be a worse, however. If you have schizophrenia within the family, you might be at risk. The doctor strongly recommended I do not take any cannabis because there is a risk it triggers a psychosis episode. I wouldn’t see cannabis having no effect as good news as that’s not representative of the average experience.
LoganDark
I've been trying to cause a psychotic episode for years and so far have not yet succeeded :)
I think the sticking point for me is that I refuse to knowingly cause myself permanent brain damage. That heavily limits my options.
csomar
Triggering a psychotic episode is a very dangerous thing as it can turn into permanent psychosis. That's one of the dangers of cannabis and LSD.
bongodongobob
This sounds snarky but you just didn't do enough.
LoganDark
I'm not sure how to do more. I think in all cases I tried to take as much as I could. I basically can't smoke or vape it because every time I try, I feel like I'm going to choke and die, and I cough for something like 5 minutes straight.
When I tried the tincture, I took 50mg of THC orally. (250mg per 30oz, so 6oz.) Although I guess I could just be unable to take THC orally, which would suck, because smoking it is miserable. (I am really not a smoker...)
bongodongobob
Yeah, edibles don't do much for me either. Hit a vape pen.
null
Perenti
As a population based study, how did they control for other substances? Acid in particular is notorious for flashbacks years later that can be psychotic. I also note that the period in question is also associated with massive increase in methamphetamine abuse. Greater access to THC being associated with an increase in crazy people using it makes complete sense, but is a causal link between legislation and schizophrenia really demonstrated amongst chronic potheads (the study is about psychosis in people with CAD), that being the subject of the paper?
elevaet
Are acid flashbacks real? I thought that was an urban myth.. I've never had one and I don't think I've ever encountered someone who has. It seems like one of those drug war era scare tactics or viral rumours.
bcoates
HPPD is probably real but it's hard to tell what the base rate is in non-users (idiopathic visual disturbances are hard to test for)
Psychotic acid flashbacks aren't real
null
djaouen
I was diagnosed schizophrenic without any use of cannabis. What prize do I get????
sandworm101
The big question remains: is this downside worse than the innumerable and absolute known downsides associated with alcohol? If not, this is a purely acedemic issue.
throw18376
I support the legality of cannabis and alcohol.
However, on an individual level, I think people need to know about the psychosis risks. It undoubtedly can trigger schizophrenia and make it much worse once it exists.
I know more than a few people who have severe alcoholism problems in their families, and just chose to never drink alcohol. I think a similar choice may be wise for cannabis if there is a history of psychosis.
On a public health level there was a theory that people would substitute cannabis for alcohol. But unfortunately, this doesn't seem to be bearing out.
baking
Previous studies have shown that young adults who are susceptible to schizophrenia are more likely to develop it if they were heavy cannabis users at a younger age. As they get older it is less likely to develop, or they are better able to keep it from developing. My brother-in-law smoked cannabis in high school and college and was hospitalized for schizophrenia when he was in college. It wrecked his life and he still has schizophrenia at age 65. I don't think it is just an academic issue.
aoanevdus
There are practical reasons to understand the effects of both cannabis and alcohol. It’s not like we can only care about one of them at a time based on which is winning the social harm olympics.
guelo
I don’t see how your conclusion follows. I quit heavy weed use because of noticeable cognitive and social problems. The warning is useful for users to know about regardless of the problems associated with alcohol.
portaouflop
alcohol is proven to kill tens of thousands every year — obviously much worse than a few people who develop mental issues.
Regardless in a free society people should have agency over what they do with their bodies.
Education about these substances is the most important thing.
lukan
"Education about these substances is the most important thing."
Indeed.
"obviously much worse than a few people who develop mental issues."
So maybe start by comparing the average heavy weed smoker, to the average non drug user, to see if the issue with cannabis is really "just some people developing mental issues"
(Disclaimer blabla: I always was pro legalisation and am happy, it finally is legal in germany now)
Perenti
History has shown that _bad_ education about substances doesn't work, as most kids know that pot rarely turns you into an axe wielding homicidal maniac. Educate using the truth - pot probably won't turn you crazy, but it might cost a lot of money and waste a lot of time.
portaouflop
For what it’s worth education sees alcohol as a much less harmful substance than weed (for example in Germany since you brought it up) - it’s completely acceptable to drink heavily every weekend to the point of almost landing in the hospital, while heavy weed use is seen as very deplorable (lazy etc).
So while weed is not without harm i think alcohol has a magnitudes worse impact on society
xyst
Explains the downfall of Elmo [1]. Bro hasn’t been the same since that fateful day on JRE.
ne0flex
>"I mean, it's legal, right?" asked the Tesla founder, before taking a drag on the joint.
"Tesla founder." You'd hope that the BBC would get right that he's not the founder but an early investor that ended up taking over the company and kicking out the original founders.
joenot443
Was it implied that was the first time he’d ever tried? That wasn’t my impression
baking
Schizophrenia develops in the twenties. Whatever his problem is, I don't think that is it.
IncreasePosts
Why intentionally mis-name someone?
When I hear people say that, it just sounds like a blind hater/memeist/chronically online person and I discount their views entirely.
We literally still call Hitler Hitler. We can call Elon Elon no matter how bad you think he is.
asadotzler
Why do you even care. If I call him JackAssElon what harm does that cause you or society that you feel the need to chastise people for it? It's kinda odd to see you jumping to his defense when literally no one else gives a shit what we call that fuckwit.
inverted_flag
This may be a joke, but with the ultra-potent weed available nowadays, one time is really all it takes to cause serious psychological changes.
null
highasfcuk
"ultra-potent weed" is weak and you need to stop with that talking point. SWIM are on 90%+ THC cartridges or concentrates 24/7. Smoking the strongest weed, low 30%s, is a tolerance break thing or for fun.
null
inverted_flag
THC% has skyrocketed over the last 20 years, that’s well documented. I know from experience that one time is all it takes to mess you up.
someothherguyy
> one time is really all it takes to cause serious psychological changes
So its the same as seeing your own mother naked
> The annual incidence of schizophrenia was stable over time, while the incidence of psychosis NOS increased from 30.0 to 55.1 per 100 000 individuals (83.7%) in the postlegalization period relative to the prelegalization period.
So increased cannabis use after legalization did not result in increased rates of schizophrenia, though it might have made some cases worse.