THE SCARY SCIENCE OF MARIJUANA

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 statistics from the United Nations 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no one noticed is 10 years out of date.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 footprint of our love for the weed?" A Globe and Mail article
titled "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 devastating brain disorder that typically produces
delusions, hallucinations, disturbances in problem solving, memory
and concentration, along with depressed mood, anxiety, and social withdrawal.

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.

This information is causing headline news in the United Kingdom, but
on this side of the Atlantic no one seems to have noticed.

In a column two years ago 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 twofold. A VAL/VAL mixture increases the risk 10 times.
Since a quarter of the population is VAL/VAL, a quarter is MET/MET
and the rest a mixture, the assessment that 25 per cent 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 that someone in that government had finally
managed to do their homework. But did anyone else?

Apparently not, even though the Canadian Journal of Psychiatry
featured marijuana and psychosis as the cover story of its summer
2006 issue. 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, 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 had not used cannabis, Mr. Murray
believes, while British rapper J-Rock, a rehabilitated skunk addict,
told the Independent 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. "B.C. Bud," "weed" and "pot" are much
less threatening words. 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
problems 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 is 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.

Margret Kopala's bi-weekly column returns on Aug. 25.