Pubdate: Sat, 14 Jan 2006
Source: Cape Argus (South Africa)
Copyright: 2006 Cape Argus.
Author: Jeremy Laurance
Cited: Advisory Council on the Misuse of Drugs
Bookmark: (Cannabis - United Kingdom)
Bookmark: (Cannabis)
Bookmark: (Decrim/Legalization)


It is the world's oldest euphoric drug, long viewed by any liberal
worth their salt as a victim of unfair drug laws.

The notion that a spliff is a safer, sweeter means of relaxing than a
beer has over the years spread way beyond its traditional student
constituency to every corner of society in Britain.

But two years after the British government listened to these voices
and the law was relaxed, its safety is under question as never before.

A report to be published within the next few weeks is expected to
confirm what some psychiatrists have been warning for years.

That cannabis, reputedly taken by Queen Victoria to banish her period
pains, may be driving its users - many of them children - insane.

Charles Clarke, the Home Secretary, has indicated that following the
report from the Advisory Council on the Misuse of Drugs, he is
planning a U-turn on the reclassification of cannabis in 2004.

Clarke is expected to take cannabis from Class C back to Class B
status, with tougher penalties for possession.

But is cannabis really so dangerous? In the last two years, evidence
has strengthened that the drug that inspired the hippie generation to
make love not war is a trigger for psychotic delusion that may confine
a small minority of vulnerable users to a lifetime in mental

There is nothing new about "reefer madness" and the exact role of
cannabis in psychosis is disputed by psychiatrists. But two
developments have increased professional anxiety about its dangers.

First, the cannabis available on the streets in Britain is stronger
than it was two or three decades ago.

Much of it is "skunk", a high-octane version of the more benign
"weed", often cultivated hydroponically (without soil) indoors, under
lamps where it is specially bred to increase the content of the main
psychoactive ingredient, tetrahydrocannabidinol, or THC.

A cannabis joint today may contain 10 to 20 times more THC than the
equivalent joint in the 1970s.

All drugs carry a risk of side effects and the more powerful the drug
the greater the risk that some users will suffer harm. Cannabis is no

Second, the age at which young people begin experimenting with
cannabis has decreased.

The younger a person is, the more susceptible they are to drugs of all
kinds. Experts believe there is a particular risk of damage to
developing brains from psychoactive drugs.

Research in Australia has shown that the age of first cannabis use has
declined since the 1970s from the early twenties to the mid-teens.

In the Netherlands, the European country with the most liberal drugs
policy, it is between 13 and 14 and in the UK it is between 15 and

Studies in the UK show that two in five 15-year-olds have tried
cannabis - more than in any other country in Europe.

The risk of the drug triggering psychosis may increase with decreasing

A psychotic episode can involve hallucinations, fantasies and a loss
of touch with reality which may last days, weeks or months and can be
very frightening. Although it is possible to have a single episode
without recurrence, the risk of attacks is increased after the first.

Robin Murray, professor of psychiatry at the Institute of Psychiatry,
has sounded the loudest warnings about cannabis, but even he says: "It
is obviously ridiculous to say everyone who smokes cannabis is going
to become psychotic. Even in our studies of adolescents, 90 percent of
those who smoked cannabis did not go on to develop psychosis."

But he points to mounting evidence that the drug can trigger psychosis
in vulnerable individuals. The big question now is: who is vulnerable?

A study by the Institute of Psychiatry, published in the journal
Biological Psychiatry last May, suggested that people with a variant
of the gene COMT, carried by 25 percent of the population, had a five
times higher risk of psychosis if they smoked cannabis.

"The gene is involved in the breakdown of dopamine in the brain and
anything that impedes this we know increases the risk of psychosis,"
explains Murray.

"We are saying a quarter of the population are vulnerable. It is the
same as for heart disease. We know some people can smoke cigarettes
and eat a high-fat diet without suffering a heart attack, but if you
have a family history or genetic predisposition then the risks are

Several other studies have shown varying proportions of the population
are at increased risk.

The drug is known to increase the production of dopamine in the brain,
an excess of which produces the hallucinations characteristic of
schizophrenia. Any drug that stimulates release of dopamine is
therefore likely to worsen the symptoms of schizophrenia.

Murray says that overall, results from a number of studies suggest
that smoking cannabis raises the risk of psychosis by two to four
times - increasing the incidence from one in 100 to up to four in 100.

In south London, where he works, the incidence of schizophrenia has
doubled since 1964.

Although this is partly accounted for by immigration - schizophrenia
is higher among Afro-Caribbeans - the rate is also up within the white

Critics argue that the evidence for cannabis's damaging effects shows
an association between the drug and psychosis, but not that one is the
cause of the other.

The more likely explanation for the link, they claim, is that people
who are in the early stages of mental illness may turn to drugs,
including cannabis, as a form of self-medication.

Cannabis is widely used by patients in mental health wards - to the
despair of psychiatrists who say it worsens their condition.

Trevor Turner, consultant psychiatrist at St Bartholomew's Hospital,
London, and vice president of the Royal College of Psychiatrists, said
there were three reasons why the case against cannabis remains to be
proved: "First, there has been no increase in schizophrenia in this
country despite a massive increase in cannabis smoking.

"Second, there is no evidence that cannabis-growing populations such
as Jamaica have a higher incidence of psychosis.

"Third, you can show an association (between the drug and the illness)
but you can't show a cause."

Patients with schizophrenia often have long-standing prior problems of
depression, withdrawal, school refusal and behavioural difficulties
before they are diagnosed.

"People feeling not quite right are likely to go for something to calm
them down. In teen culture that is cannabis," says Turner, who has
spent decades as a front-line psychiatrist in Hackney, east London.

He says he has never seen a case of cannabis-induced psychosis.
Cannabis smoking might trigger the emergence of schizophrenia sooner
than it would otherwise have emerged - but it did not cause it. "It
could well be that cannabis makes overt a covert disorder," he says.

But he concedes that the risks of skunk are greater, due to its higher
concentration of THC.

There are at least 60 active constituents of cannabis and the higher
the content of THC the more "spacy" the effects of the drug.

The higher the content of a second constituent, cannabidinol, the more
tranquillising its effects.

"Any drug that has psychoactive effects can have toxic effects. It is
like drinking whisky instead of beer," he says.

Although Murray and Turner disagree on the exact role of cannabis in
psychosis, they agree that criminalising cannabis smoking is unlikely
to reduce the harm.

Turner says the safest option would be to legalise the drug so that
its quality and strength could be controlled and users screened to
minimise harm. Legalisation would have to apply across Europe to
prevent drug tourism.

"By not legalising it you bring the law into disrepute among the young
and you criminalise an activity that is harmless for the great
majority of people. It is poisoning society."

Murray believes education is the key. The Advisory Council on the
Misuse of Drugs has called for an education campaign about cannabis,
the only recommendation from its report that the home secretary
revealed last week and pledged to implement.

"People should know the risks of cannabis," says Murray.

"Consumption has decreased in the last year because of all the fuss
about it. We need a campaign like the anti-smoking campaigns in the
US. This is one of the rare occasions when we should follow the
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MAP posted-by: Richard Lake