The Scary Science of Marijuana
by Margret Kopala

Published in the Ottawa Citizen, July 26, 2007

Scientific developments have established that as many as one in four cannabis users is genetically at risk for developing schizophrenia or a related psychotic disorder.

Given recent UN statistics citing Canada as the industrial world’s leading consumer of cannabis, this information should set alarm bells ringing. Instead, Canada’s mainstream media responded as if someone had passed out The Happy Hippy Hymn Book that no one noticed is ten years out of date.

“Legalizing pot makes sense,” intoned a National Post editorial. Comparing cannabis with alcohol and tobacco, it asked where’s the “health foot print of our love for the weed?” A Globe and Mail article entitled The True North Stoned and Free giggled about Canada’s “little pot habit”. Then there were the columnists. Suffice to say only one mentioned the word ‘psychosis’ and that, only in passing.

Schizophrenia is a brain disorder that typically produces delusions, hallucinations, paranoia, disturbances in problem solving, memory and concentration, along with depressed mood, anxiety, and social withdrawal. The net effect is devastating and can require extensive medication.

The causes of schizophrenia are not fully understood though environmental stressors (childhood trauma, neglect) are thought to interact with genes to produce disruptions in brain chemistry. Studies conducted in Europe, New Zealand and the United Kingdom have demonstrated that cannabis is one of those stressors and that with their rapidly developing brains, the young are particularly vulnerable. The younger the user and the higher the potency of marijuana’s active ingredient, tetrahydrocannibol (THC), the greater the risk.

In a column published by the Ottawa Citizen in August of 2005, I described how genes and marijuana could interact to increase risk of developing psychosis. The COMT gene, consisting of a MET type and a VAL type, metabolizes dopamine, a brain chemical that produces the ‘highs’ characteristic of drug and alcohol use. A MET/VAL mixture increases risk of psychosis from cannabis two fold. A VAL/VAL mixture increases the risk ten times. Since a quarter of the population is VAL/VAL, a quarter is MET/MET and the rest a mixture, the assessment that 25% of youth are at risk is probably conservative.

That column resulted from an interview I had conducted with the world’s pre-eminent authority on marijuana and psychosis, Professor Robin Murray. Lead and co-author of countless studies on the subject, he is also professor of psychiatry at King’s College Institute of Psychiatry in London and co-author of the standard textbook on this issue, Marijuana and Madness. He also led criticism of British government policy that ignored the mental health issues associated with marijuana use.

To its credit, Paul Martin’s Liberal government quietly withdrew its marijuana decriminalization bill shortly after publication of my 2005 column. I like to think someone in that government had finally done their homework. But did anyone else?

Apparently not, even though the Canadian Journal of Psychiatry featured marijuana and psychosis in its summer 2006 issue and recently Addiction magazine predicted that a quarter of new cases of schizophrenia by 2010 will result from cannabis smoking.

In March of this year, The Independent – a major British newspaper – retracted and apologized for its stand on decriminalizing marijuana . “Record numbers of teenagers are requiring drug treatment as a result of smoking skunk,” it explained, “the highly potent cannabis strain that is 25 times stronger than resin sold a decade ago”.

At least 10 per cent of that nation’s schizophrenics could have avoided the illness if they hadnot use cannabis, Professor Murray believes, while British rapper J-Rock, a rehabilitated skunk addict, told the same paper that “If you’re on skunk and you have a confrontation with somebody, you feel almost untouchable,.”

“Skunk induced paranoia,” The Independent concluded, “is behind the surge in violent crime.”

Remember, once you are psychotic, you don’t need continued hits of marijuana to behave aggressively or to experience paranoia. The illness has been triggered.

Canada has yet to adopt the skunk moniker. For happy hippies, “BC Bud”, “weed” and “pot” are much cosier. But make no mistake, with today’s growing technologies, all the above are just as potent as European skunk.

A UN spokesperson recently observed that countries get the drug problem they deserve. So by all means, let us discuss the relative merits of legalizing or decriminalizing marijuana use. One scientist has suggested it could be regulated according to potencies. Others are finding possible benefits for psychosis that are drowned out by high THC levels. But so long as that discussion ignores the overall health effects of marijuana, Canada will get the drug problem it deserves. Indeed, it’s probably already arrived.

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