Jake Ellison at Seattle PI - the Pot Blog...
But why is marijuana associated with schizophrenia?
ThatÂs what researchers are trying to figure out, and there have been three key studies, recently published, that point in two different directions, which is why I chose to start this story as I did. Rather than blast out headlines that contribute to the whipsaw, head-jerking of ÂYes it does! and ÂNo it doesnÂt! letÂs start with what none of this research does.
None of the research on cannabis and schizophrenia establishes or disproves a causal link. No research has proven that ingestion of the chemicals in marijuana causes physical damage that results in clinical psychosis (as opposed to just thinking someone is stupid or nuts).
What two of the research articles IÂll bring up do establish is a correlation between marijuana use and the presence of brain structure anomalies found in people with schizophrenia. The third research finding establishes that there is no strong correlation between cannabis use and schizophrenia.
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So, if this risk of schizophrenia is proven, will that stop the forward progress of legalization?
Just a guess here, but IÂm gonna say, Nope. Voters donÂt appear to think that marijuana is good for you  they appear to be voting it in because it isnÂt any worse, at least, than alcohol and the war on drugs causes more social and personal damage than the drug itself.
Legalization is not creating marijuana use nor a market for it. After decades of prohibition, use has even slightly increased over that time. So itÂs not like folks are going to suddenly stop using because of some bad news on the research front. And until people decide to stop using cannabis, weÂll be right where we are with a raging black market and prisons full of non-violent offenders.
 after all itÂs taken decades to reduce smoking, and alcohol consumption seems totally unimpaired by the litany of body and brain killing side effects.
HereÂs that paragraph from professor Robin Murray, from KingÂs College London:
It is difficult to look at the relationship between environmental and genetic factors, but we have examined that question in relation to cannabis. We now know that there is an interaction between the catechol-O-methyl transferase gene (COMT), which some regard as a susceptibility gene for schizophrenia, and cannabis consumption. People with the Val/Val variant of COMT are much more likely to develop psychosis if they abuse cannabis in their adolescence, but there is no evidence that people with the Val/Val genotype of COMT actually take more cannabis than the rest of the population. So itÂs not that the cannabis consumption is a manifestation of predisposition to schizophrenia. Rather, cannabis consumption interacts with genetic susceptibility to schizophrenia. The result is that the majority of the population can abuse as much cannabis as they like and donÂt come to much harm. But a vulnerable minority, about 25 percent of the population, is prone to psychotic reactions if they take regular cannabis (Caspi et al., 2005).
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FWIW.
Cheers,
Scott.
