'REEFER MADNESS' THEORY RESURFACES

Review Of Studies Finds Cannabis Use Can Trigger Schizophrenia In
People Vulnerable To The Illness

A pair of articles in the Canadian Journal of Psychiatry has
resurrected the "reefer madness" argument about marijuana and its
links to mental illness.

Cannabis use can trigger schizophrenia in people already vulnerable to
the mental illness, and this fact should shape marijuana policy, two
psychiatric epidemiologists claim in this month's journal.

The link between marijuana use and schizophrenia is generally accepted
in the psychiatric community. The problem is that the vulnerable
population -- mostly teenagers -- generally isn't eager to absorb the
message.

Australian epidemiologists Louisa Degenhardt and Wayne Hall reviewed
eight international studies of teens and young adults that examined
the link between marijuana use and schizophrenia. They concluded that
using marijuana can precipitate schizophrenia in users who have a
personal or family history of schizophrenia.

One 15-year study of 50,000 young people in Sweden, for example, found
that those who had tried marijuana by the time they were 18 were 2.4
times more likely to receive a diagnosis of schizophrenia. The Swedish
researchers concluded that 13 per cent of schizophrenia cases could be
averted if all cannabis use were prevented.

Another study of almost 5,000 subjects in the Netherlands replicated
the findings, and found that marijuana users were more likely to be
diagnosed with schizophrenia during the study's three-year follow-up
period. Other studies suggested that subjects who used pot in their
early teens were more likely to be diagnosed with schizophrenia by
their mid-20s.

In a companion article, Hall and Degenhardt argue that the evidence
has policy implications. Young people should be warned of the
marijuana-schizophrenia link -- most schizophrenics are diagnosed by
their late teens, about the same time teens are experimenting with
pot.

The link has been used to argue in favour of recriminalizing pot in
some Australian states. However, only one per cent of the population
will be diagnosed with schizophrenia in their lifetimes.

Hall, a researcher at the University of New South Wales in Australia,
said it's a tricky argument to make when, by the numbers, marijuana
will adversely affect so few people. But he points out that
schizophrenia has a high personal and economic cost.

Alan Young, a criminal law expert at York University's Osgoode Hall
Law School in Toronto, said linking pot and mental illness has been
around for decades.

"This is that old hobgoblin that resurfaces now and again. There's
nothing new in the literature. They just keep rehashing the old
literature."

Young said there isn't enough of a causal link in high enough numbers
for the link to be a concern. If marijuana presented a real threat,
there would be an epidemic of schizophrenia. The figures show that the
percentage of schizophrenics in society has remained stable, he said.