Dr. Michael O'Malley assertes that "incidence of psychosis has already been documented by some of the states in the U.S., who rushed to legalization of marijuana." ("Pot stance off-base," Letters, Aug. 16).
There is no evidence that cannabis usage rates have gone up in the U.S. states that have legalized cannabis, much less that rates of psychosis have increased.
There is some evidence that cannabis strains that are high in THC but low in the anti-psychotic cannabinoid CBD, as well as some important terpenes, may trigger psychosis in minors so predisposed.
Unfortunately, black market cultivators and dealers prefer such strains and they do not require proof of age.
Researchers concede that it is too early to tell how legalization will impact usage rates, however, several studies have determined that usage rates rise and fall with no statistical relationship to cannabis laws and their enforcement. For example, Dutch youth use cannabis at about half the rate of Canadian youth, despite or because of the availability of cannabis to adults in "coffee shops."
We have more control over cat food than we do over the so-called "controlled drugs and substances," as evidenced by the health warnings Dr. O'Malley has observed on cigarette packages and the steady decline in tobacco smoking, despite our refraining from criminalizing tobacco smokers and incarcerating convenience store owners and clerks.
Matthew M. Elrod
Victoria
