
Marijuana use and schizophrenia: New evidence suggests link - Mz
http://www.medicalnewstoday.com/articles/314896.php
======
oblib
I've seen these studies for years now and they always conclude the same thing
but twist the headline and omit very important data in their study. They
conclude:

"There is growing consensus that cannabis use might increase the risk of
developing schizophrenia. Our results support this, but also suggest that
those at increased risk of schizophrenia may be more likely to try cannabis in
the first place."

I've never found any good reason to suspect a link between use and cause in
their data and the link between schizophrenia and use is almost always
consistent with use of other drugs as well, and most any drug as far as that
goes. For example, almost all of those who used marijuana also used alcohol
and prescriptions drugs as well, but links to those (and combinations of them)
are completely or mostly ignored in these studies.

Furthermore, they almost always suggest that "Paranoia" is one of the symptoms
that Marijuana causes but they never address the fact that everyone they study
has grown up with a lifetime of harsh disinformation and the very real threat
of imprisonment for taking just a puff off a joint, which is a very good
reason to get paranoid if you do.

As they say "Just because I'm paranoid doesn't mean they're not out to get
me." and in this case "They" most certainly have been and still are in most
places and everyone has seen it happen. The real result of that is, if you're
not paranoid you're a idiot and most schizophrenics are not idiots. Some of
them are geniuses. ([https://www.psychologytoday.com/blog/beautiful-
minds/200903/...](https://www.psychologytoday.com/blog/beautiful-
minds/200903/schizophrenic-thought-madness-or-potential-genius))

~~~
DanBC
> Furthermore, they almost always suggest that "Paranoia" is one of the
> symptoms that Marijuana causes but they never address the fact that everyone
> they study has grown up with a lifetime of harsh disinformation and the very
> real threat of imprisonment for taking just a puff off a joint, which is a
> very good reason to get paranoid if you do.

This is a british study.

[http://www.rcpsych.ac.uk/healthadvice/problemsdisorders/cann...](http://www.rcpsych.ac.uk/healthadvice/problemsdisorders/cannabis.aspx)

> A young person found to be in possession of cannabis will be:

> Arrested

> Taken to a police station

> Given a reprimand, final warning or charge, depending on the offence.

> After one reprimand, a further offence will lead to a final warning or
> charge.

> After a final warning:

> The young person must be referred to a Youth Offending Team to arrange a
> rehabilitation programme.

> A further offence will lead to a criminal charge.

That's pretty far from being imprisoned for a single puff.

~~~
oxide
Trust me, being arrested is fucking terrifying. Being under threat of
persecution for getting a little high is a definite paranoia-inducer.

Do you think 'they know' would be a concern if police couldnt cuff you for
doing it? Search your personal property over a smell they may not smell?

~~~
DanBC
> Trust me, being arrested is fucking terrifying

Sure. That wasn't the claim though. The claim was "imprisoned for a single
puff", which just doesn't happen in the UK.

------
_98fj
Isn't it established since about 25 years that any drug-use can bring onset of
schizophrenia in those vulnerable?

~~~
DanBC
The correlation between drug use and schizophrenia is very clear.

There's considerable debate about the causality.

Does psychosis cause people to smoke more cannabis? (It causes people to smoke
more cigarettes).

Does cannabis cause people who would not have had psychosis otherwise to get
it?

Or does cannabis just bring out an underlying psychosis that the person
probably would have experienced anyway?

It's probably a bit complicated, with circular stuff going on.

While I'm strongly in favour of legalisation of all drugs I am a bit worried
when some of the legalise crowd refuse to accept that there might be health
risks. (I'm also frustrated when the anti crowd refuse to accept that the
situation is probably a bit more complicated than "drugs make you mad")

~~~
kahnpro
Or is it that people who have schizophrenia often belong to social classes
that are more likely to use drugs?

If poor people are more likely to use drugs, and poor people also have a
higher incidence of schizophrenia, you could arrive at this correlation even
if marijuana and psychosis are entirely unrelated.

~~~
mistersquid
Marijuana use actually may be more strongly correlated to higher socioeconomic
status than lower.

A quick Google search for "drug use by socioeconomic status" turns up a 2012
article titled "Socioeconomic Status and Substance Use Among Young Adults: A
Comparison Across Constructs and Drugs" [0] which concludes, in part

    
    
      > Findings based on three indicators of family background
      > SES—income, wealth, and parental education—converged in
      > describing unique patterns for smoking and for alcohol and
      > marijuana use among young adults, although functional
      > relationships across SES measures varied. Young adults with
      > the highest family background SES were most prone to alcohol
      > and marijuana use.
    

[0]
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3410945/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3410945/)

EDIT: Change lede.

------
reflexive
Anecdotal evidence: Kurt Vonnegut's son Mark wrote a fascinating book ("The
Eden Express", 1975) about his experience being schizophrenic and a prolonged
psychotic episode triggered by marijuana consumption:
[https://en.wikipedia.org/wiki/The_Eden_Express](https://en.wikipedia.org/wiki/The_Eden_Express)

------
sreeni_ananth
[https://www.ncbi.nlm.nih.gov/pubmed/8689377](https://www.ncbi.nlm.nih.gov/pubmed/8689377)
seems to suggest increased paranoia with alcohol consumption as well. Probably
makes the condition worse rather than being the root cause.

------
andai
My friend in med school mentioned a study that found a number of genes for
which smoking cannabis increases risk of developing schizophrenia, and a small
number for which smoking cannabis actually decreases it! If anyone has heard
of this I'd love a link to the study

------
sigstoat
as i understand it, the growing opinion of toxicologists (who, if drug use
comes up in court, are the ones who get to have expert opinions on what drugs
do), is that the delta-9-THC can cause short term psychosis. on the other
hand, CBD prevents it (and has most of the non-recreational benefits of the
plant). further, THC and CBD levels can vary dramatically by strain.

in this study, they do claim to measure THC concentration, but don't measure
or talk about CBD, and have a sample size of 17.

there's stuff going on that needs to be studied, but this study isn't
contributing anything useful.

------
sageikosa
tl;dr; those prone to schizophrenia may increase psychosis risk if they are
consumers of marijuana.

~~~
DanBC
The article links to the study (this is great, and I wish more people did
that). The study has a nice tl;dr

[https://www.cambridge.org/core/services/aop-cambridge-
core/c...](https://www.cambridge.org/core/services/aop-cambridge-
core/content/view/122D651C3670683DAEDDA33997417105/S0033291716003172a.pdf/div-
class-title-assessing-causality-in-associations-between-cannabis-use-and-
schizophrenia-risk-a-two-sample-mendelian-randomization-study-div.pdf)

> Results. There was some evidence consistent with a causal effect of cannabis
> initiation on risk of schizophrenia [odds ratio (OR) 1.04 per doubling odds
> of cannabis initiation, 95% confidence interval (CI) 1.01 1.07, p = 0.019].
> There was strong evidence consistent with a causal effect of schizophrenia
> risk on likelihood of cannabis initiation (OR 1.10 per doubling of the odds
> of schizophrenia, 95% CI 1.05–1.14, p = 2.64 × 10−5). Findings were as
> predicted for the negative control (height: OR 1.00, 95% CI 0.99–1.01, p =
> 0.90) but weaker than predicted for the positive control (years in
> education: OR 0.99, 95% CI 0.97–1.00, p = 0.066) analyses.

> Conclusions. Our results provide some that cannabis initiation increases the
> risk of schizophrenia, although the size of the causal estimate is small. We
> find stronger evidence that schizophrenia risk predicts cannabis initiation,
> possibly as genetic instruments for schizophrenia are stronger than for
> cannabis initiation

------
jack9
Looks a lot like propaganda. Not saying it's inaccurate, but pointed squarely.

~~~
andai
Well.. if you have a latent mental illness and you take psychoactive
substances, you may have a bad time.

The issue is complicated: people often don't know about their illness and
don't know that they respond differently to substances than other people do.

I'm looking forward to a future where genetic testing for these things is as
common as testing your drugs for purity (which, i hope, will also be be more
common!)

~~~
jack9
> you take psychoactive substance

So are they going to release individual studies for each of the other
substances? This is the crux of the issue for me.

~~~
Broken_Hippo
Hopefully we'll get to that point. It isn't like the research is complete in
any way.

