Research Contribution of cannabis use disorder to new cases of schizophrenia has tripled

[C C]

Contribution of cannabis use disorder to new cases of schizophrenia has almost tripled over the past 17 years
https://www.eurekalert.org/news-releases/1072286

EXCERPTS: The proportion of new cases of schizophrenia associated with a cannabis use disorder has risen from 4% pre-legalization to 10% after cannabis legalization in Ontario, according to new research.

A new study from researchers at ICES, The Ottawa Hospital, University of Ottawa’s Department of Family Medicine, and Bruyère Health Research Institute and published in the journal JAMA Network Open used data capturing the healthcare visits of everyone living in Ontario, Canada to track whether the liberalization of medical cannabis in 2015 and legalization of non-medical cannabis in Canada in 2018 were linked to changes in how much cannabis use disorders (CUDs) were associated with new schizophrenia cases.

“Regular cannabis use is strongly associated with an increased risk of schizophrenia, and one of the main areas of uncertainty surrounding cannabis legalization is whether there would be changes in the number of new cases of schizophrenia,” says Dr. Daniel Myran, a Canada Research Chair in Social Accountability at the University of Ottawa, ICES Adjunct Scientist, Investigator at the Bruyère Health Research Institute, and Associate Scientist at The Ottawa Hospital.

“We found that there have been concerning increases over time in the percentage of people with a new schizophrenia diagnosis who had received care for a cannabis use disorder before their diagnosis.” [...] “Our study highlights the growing public health challenge posed by the combination of increasingly high-potency cannabis and rising regular cannabis use,” says Dr. Myran.... (MORE - details)

[stryder]

As always stated the problem with the mention of the "studies" is they lack expressing whether they tested the difference in admission (Whether it was smoked or taken orally) I'd suggest it's likely that Schizophrenia is more prevelant through smoke inhalation due to the toxicology of smoke itself (Whether cannabis was present or not).

[Syne]

If that were the case, cigarette smokers would show more schizophrenia.

[Yazata]

My first thought reading that is that "correlation does not imply causation".

I've known a few schizophrenics over the years and they all tended to self-medicate with alcohol, marijuana (I guess they call it 'cannabis' now) or various opiates. Pretty much all of the anti-psychotic drugs that shrinks prescribe are either ineffective or have devastating side effects. So the psychotics themselves much prefer to employ means that take the edge off the voices/delusions whatever, that they can actually enjoy and much better tolerate.

I'm not yet convinced that cannabis use causes schizophrenia. It might just be that Ontario making cannabis more available increases the likelihood that schizophrenics will make use of it.