>We have evidence suggesting that cannabis use, primarily THC in cannabis, in genetically predisposed or at-risk populations, leads to earlier diagnosis of psychosis/schizophrenia. This tells us that THC in cannabis has a small causative effect on schizophrenia.
A small effect on people who were already at risk. The sky is hardly falling with legalization.
Emphasis mine. This seems interesting to me. Earlier diagnosis is not more diagnosis. It could just mean that due to illegality, these people got into contact with mental health professionals earlier than they would have otherwise. Also getting the diagnosis earlier. But not being more schizophrenic.
I'm generally pro-legalization, but if marijuana is shown to make people schizophrenic who would otherwise not become schizophrenic, it's a big deal. It has severely affected their lives and those around them. Tobacco doesn't give everyone lung cancer after all, some are more at-risk than others. Quantitatively determining that risk, doing cost-benefit, etc, is important, but I don't think this should be dismissed out of hand as immaterial.
> The relation between cannabis and schizophrenia needs further investigation. We need more case-control studies and clinical trials with a larger population to get conclusive data.
From the current data, we can conclude that the tetrahydrocannabinol (THC) component of cannabis can be the main culprit causing psychosis and schizophrenia in the at-risk population. THC can also be the one exacerbating symptoms and causing an adverse prognosis in already diagnosed patients.
It is a well-known fact that many of the abuse substances cause psychosis, which is a part of the schizophrenia spectrum; cannabis is one [9]
Nevertheless, the fact remains that schizophrenia and psychosis walk hand in hand alongside with cannabis use. Cannabis has many strains with different ratios of components. The ratio of THC and CBD is the most important psychotomimetic property of any cannabis strain [14]. When a healthy person uses cannabis, he experiences relaxation, euphoria, and a decrease in anxiety and boredom. However, they might also have some undesirable effects like paranoia, grandiosity, agitation, hallucination, cognitive impairment, disorganized thinking and behavior, and depersonalization [17]. People predisposed to the development of psychotic illness are more vulnerable to the psychotomimetic effects of cannabis, more specifically, THC [16,17].
Per se cannabis does not cause schizophrenia or psychosis. However, we have longitudinal data supporting the causal link between cannabis and psychosis [18].
A small effect on people who were already at risk. The sky is hardly falling with legalization.