TEENS WARNED POT SMOKING COULD LEAD TO SCHIZOPHRENIA

Called 'Reefer Madness' In the Olden Days

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 illness -- and this fact should shape marijuana policy, argue two
psychiatric epidemiologists.

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

Australian epidemiologists Louisa Degenhardt and Wayne Hall 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.

Other studies suggested that subjects who used marijuana in their
early teens were more likely to be diagnosed with schizophrenia by
their mid-20s.

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 cannabis.

The link has been used to argue in favour of recriminalizing marijuana
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 Sydney,
said it's a tricky argument to make when, by the numbers, marijuana
will adversely affect so few people.

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.

"Young people should know about the link and be on the lookout for
schizophrenic symptoms that show up among their friends who smoke
marijuana," Hall said.

He also argued that penalties for growing pot should depend on the
potency of the product. Police action has pushed growers indoors, and
these crops are more potent, he said.

Wende Wood, a psychiatric pharmacist at the Toronto-based Centre for
Addiction and Mental Health said people who want to smoke marijuana
should wait until they are at least 25 -- the human brain had
developed fully by that time, and if schizophrenia is present, it has
usually already become apparent.