Interesting. My dad developed schizophrenia in his twenties and had been smoking a lot of marijuana. I have always wondered if the smoking triggers something in him. I will always wonder.
I’m curious how we could ever reasonably parse cause and effect here? I think it’s possible smoking a lot of marijuana triggers something in certain people that causes schizophrenia but I also think it’s possible that people in the early stages of schizophrenia might seek out marijuana as a way of self-soothing. Or maybe it could even be a bit of both?
FTA: "For example, in Denmark, the incidence of schizophrenia steadily increased from 2000 to 2012 (Kühl, Laursen, Thorup, & Nordentoft, Reference Kühl, Laursen, Thorup and Nordentoft2016), and the schizophrenia population attributable risk fraction (PARF) for CUD increased three- to fourfold over the past two decades, parallel to increases in THC concentration (Hjorthøj, Posselt, & Nordentoft, Reference Hjorthøj, Posselt and Nordentoft2021). The increased THC content may thus, along a potential increase in the prevalence of CUD, be a main driver of the population-level increase in PARF between CUD and schizophrenia."
The explanation "increased THC content causes more schizophrenia" is clearly more plausible than "more schizophrenia causes increased THC content".
For a bit of anecdata, I have anxiety, and sometimes THC can exacerbate the condition (but usually helps to lower my anxiety, which is one of the reasons I still use it). If I feel anxiety coming on, I will often take a CBD gummy to help "level" out the effects of the THC. The potency of cannabis, and the "norm" of commercialization delivering greater highs, has definitely effected my anxiety. In the 1990s, when THC levels were lower, I never had anxiety from cannabis use.
In 2000 Denmark was spending 2496$ yearly per capita on healthcare, in 2012 it was 6004$(taking inflation into account: 2496$ in 2000 was 3,327.91$ in 2012)
Maybe they just got better at detecting it?
Your reasoning is akin to saying that it's likely that vaccines cause autism because of some overlapping charts, correlation is not causation.
It could, though there is some work I believe on certain receptors which THC also happens to increase the activation of activating latent schizophrenia.
