Pubdate: Thu, 02 Dec 2004
Source: Daily Telegraph (UK)
Copyright: 2004 Telegraph Group Limited
Contact:  http://www.telegraph.co.uk/
Details: http://www.mapinc.org/media/114
Author: Nic Fleming, Health Correspondent
Bookmark: http://www.mapinc.org/find?207 (Cannabis - United Kingdom)

MENTAL HEALTH WARNING FOR CANNABIS USERS

Young people with a family history of mental illness were warned
yesterday that smoking cannabis substantially increases their chances
of developing psychiatric problems.

Those who are genetically vulnerable to psychosis double the risks of
hallucinations, paranoia and serious conditions such as schizophrenia
by using the drug.

'Cannabis can be the trigger to lifelong mental illness'

The study, to be presented at an Institute of Psychiatry conference in
London today, confirmed previous findings that for an average person
taking cannabis once or twice a week the risk of suffering psychotic
symptoms roughly doubles in later life.

Prof Jim van Os, a psychiatrist at Maastricht University in the
Netherlands, said: "There have been a number of studies that have
shown that cannabis use roughly doubles the risk of psychiatric
illness such as schizophrenia among young people.

"There have been suggestions that cannabis can interact with
pre-existing, possibly genetic, vulnerability to psychotic symptoms.

"Our results show that in the group with no pre-existing vulnerability
to psychosis, cannabis use increased the chances of the onset of
psychosis by a small amount.

"However for those who had shown evidence of being predisposed, the
increased risks of developing problems were four times greater than
for those not considered vulnerable."

The new research, published by bmj.com, opens the way to the
possibility of a genetic test that would tell people if they were at
greater risk from cannabis use and of better targeting of public
health advice.

Prof van Os's team interviewed 2,437 Germans aged 14 to 24 to assess
their drug use and vulnerability to psychosis by asking questions
designed to reveal traits such as paranoia, suspicion and delusions.

Ten per cent were viewed as potentially vulnerable to psychotic
symptoms, ranging from hallucinations and delusions to serious
conditions requiring hospital treatment.

The group was assessed four years later. Of those found not to be
predisposed to psychosis, 15 per cent of those who did not use the
drug and 21 per cent of those who did experienced some symptoms.

Among the volunteers identified as genetically vulnerable to
psychosis, 51 per cent of cannabis users had symptoms compared with 26
per cent of those who did not use the drug.

Across the whole group, cannabis use, defined as at least five times,
was found to increase the risk of psychosis by two thirds. Using the
drug on average between once and twice a week increased the chances of
symptoms by 95 per cent.

Prof van Os said: "The public health message is that if people have a
family history of mental instability then they should know there are
high risks associated with cannabis use."

Other researchers said the risks of mental illness were also increased
by the trend in recent years of increasing amounts of THC - the active
ingredient in cannabis - in the drug, and young people starting to use
it earlier.

A report released last week showed that schoolchildren in England were
using more cannabis than in any other country in Europe. The European
Monitoring Centre for Drugs and Drug Addiction disclosed that among
15-year-olds, 42 per cent of boys and 38 per cent of girls had tried
cannabis, compared with less than 10 per cent in Greece, Malta, Sweden
and Norway. More than one in 10 15-year-olds in England reported heavy
cannabis use - defined as 40 or more occasions a year - compared with
the next biggest groups of seven per cent in Spain and Belgium.

Marjorie Wallace, the chief executive of the mental health charity
Sane, said: "The evidence is mounting that cannabis can be the trigger
to lifelong mental illness. We need to make these risks known, clamp
down on drug dealing in such places as playgrounds and hospital wards,
and change perceptions of cannabis from being a recreational relaxant
to a dangerous substance for those who are vulnerable."
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MAP posted-by: Derek