EXPERTS RESURRECT 'REEFER MADNESS' AS REASON TO CRACK DOWN ON
MARIJUANA

Drug Linked To Schizophrenia In Teens, But Authors Say General Risk Is
Slight

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,
argue two psychiatric epidemiologists 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 is small and mostly teenagers, an audience that 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 was prevented.

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

In a companion article, Mr. Hall and Ms. 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
cannabis.

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

Mr. Hall, a researcher at the University of New South Wales in
Australia, admits 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.

Although it's unlikely a vulnerable person will develop the illness
after smoking a single joint, Mr. Hall said, some studies suggest
marijuana smokers are two or three times more likely to be diagnosed
with schizophrenia. In Australia, where marijuana use is heavy among
teens, it's not uncommon for 20 to 30 per cent of new episodes of
schizophrenia to be among patients who use marijuana daily or almost
daily.

"There are a lot of other reasons to discourage young people from
using cannabis," said Mr. Hall, who believes young people should know
about the link and also be on the lookout for schizophrenic symptoms
that show up among their friends who smoke marijuana.

He also argues that penalties for growing marijuana should depend on
the potency of the product. Authorities cracking down on field-grown
crops have inadvertently pushed growers indoors, and these crops are
more potent, he said.

Wende Wood, a psychiatric pharmacist at the Centre for Addiction and
Mental Health in Toronto, said people who want to smoke marijuana
should wait until they are at least 25 -- the human brain has
developed fully by that time, and if schizophrenia is present, it has
usually already become apparent. (She argues that the drinking age is
too low for the same reason.)

Cannabis users who have schizophrenia are harder to treat and
marijuana makes their psychosis worse, she said. Some marijuana users
who are not schizophrenics also experience feelings of anxiety, panic
and paranoia, but this is temporary.

But no one knows how to gauge predisposition to schizophrenia. The
question is how to present the evidence to teens without falling back
on the old "reefer madness" message, which teens find laughable, said
Ms. Wood, who frequently speaks to groups of teens about drug issues.
Even the Centre for Addiction and Mental Health has issued a statement
saying that for most people, cannabis doesn't cause harm.

"Kids say 'It's not going to be me.' And with some kids, danger is
part of the appeal," she said.

Alan Young, a criminal law expert at York University's Osgoode Hall
who has been at the forefront of legal battles surrounding marijuana,
said linking marijuana and mental illness has been done 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."

Mr. Young argues that 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.

"The numbers are really small considering the number of users
worldwide," said Mr. Young.

He also disagrees with the argument that greater potency will lead to
more harm.

"You just smoke less," he said. "It's perfectly harmless for the vast
majority of users."