THE GREAT CANNABIS DEBATE: 50 TOP EXPERTS CONFIRM MENTAL HEALTH RISK

Since the 'IoS' reversed its policy on legalising cannabis because of
the drug's links with mental illness, many have joined the campaign
to highlight its dangers. Here we report on the latest findings to
cause concern.

A poll of more than 50 of the world's leading authorities on drugs
and mental health confirms that most believe cannabis, and
particularly its stronger variant, skunk, pose significant health
risks and increase users' susceptibility to psychosis and schizophrenia.

The Government's announcement last week of a review that could see
the reclassification of the drug and harsher penalties for possession
re-ignited the debate about the risks of using cannabis.

Launching the three-month consultation, Jacqui Smith, the Home
Secretary, said: "Government must remain responsive - alive to new
evidence, feedback and trends." Health ministry sources said that new
medical evidence about the link between cannabis and mental illness,
reported first in this newspaper, would form "a key part of the
evidence" that the Government will consider.

It will also examine a new study published in The Lancet last week,
which said that cannabis users increased their risk of suffering
psychotic episodes by some 40 per cent. The findings by the team at
Bristol and Cardiff Universities, led by Dr Stanley Zammit, said that
some 14 per cent of psychotic episodes among young people could be
prevented if they avoided the drug.

Inquiries by the IoS have drawn warnings from a wide range of
organisations, such as the Royal College of Psychiatrists, and
specialists. They include Professor Colin Drummond, addiction
psychiatry and consultant psychiatrist at St George's Hospital,
London, Professor Yasmin Hurd, from the department of psychiatry and
pharmacology at New York's prestigious Mount Sinai School of
Medicine, Dr Andrew Johns, consultant forensic psychiatrist, at the
Maudsley Hospital in London, and Dr Raj Persaud, Gresham Professor
for Public Understanding of Psychiatry.

The drug destroys lives by causing or precipitating psychosis in the
vulnerable, argued Dr Persaud. "Just a little cannabis, if you have
the wrong genetic make-up, will precipitate psychosis," he argues.
"Many in my experience commit suicide secondary to psychosis brought
on by cannabis, so it is lethal."

Reports of stabbings, murders and suicides caused by psychotic
delusions after smoking cannabis have flooded the press in recent
months. Perhaps most worryingly, it is Britain's teenagers who are
most at risk due to the drug's effects on the developing brain, warn
leading experts.

"Young people who otherwise would have been very unlikely to
developed psychosis will, as a result of their early cannabis use, be
affected by a life-long and severely disabling mental illness that
will markedly narrow their life choices and quality of life," said
Professor Drummond.

More than 22,000 people needed treatment for cannabis use in Britain
last year. It was after publishing these figures that this newspaper
revised its stance, abandoning all previous calls for legalisation of the drug.

The decision has been praised by many, including Professor Hamid
Ghodse, the director of the International Centre for Drug Policy, who
said: "The risks of cannabis have been overlooked for many years no.
I'm glad your paper is making the public aware of the dangers.
Cannabis is not the harmless drug which many people may have believed."

The main problem, according to medical authorities, is that it is
impossible to predict with certainty people who might be vulnerable
to psychosis and schizophrenia, aside from those with a family
history of such problems.

Professor Hurd said: "Cannabis is a dangerous drug, in particular for
the developing brain and for individuals with underlying psychiatric
disorders."

Dr Mike McPhillips, the consultant psychiatrist runs the addiction
unit at The Priory. He says that they are now seeing new patients on
a monthly basis whose psychosis has been triggered by cannabis. "Ten
years ago we'd hardly ever get a patient coming in for cannabis
addiction but it is not uncommon now. The age at which people start
taking the drug is a real concern. This drug is everywhere and very
young children are experimenting with this as their first drug. We
are already seeing the consequences of this and among those who are
subject to mental illness anyway it is catastrophic."

Dr Linda Harris, clinical director of the substance misuse unit at
the Royal College of General Practitioners, said: "From a mental
health perspective we do need to look at the reasons behind a society
that's drifting towards depressing and anxiety - cannabis could be a
factor in this."

The medical profession is not alone in worrying about the possible
long-term damage to the country's estimated 2 million cannabis users.
Teachers are concerned that the casual acceptance of cannabis will
result in an epidemic of children having problems at school. Anthony
Seldon, the head of Wellington College, says the drug is "wrecking
lives" and describes it as "pernicious". He is among those that think
the decision to reclassify cannabis from a Class B to a Class C drug
was a mistake and should be reviewed. "The message must be total
prohibition," he said.

Keith Hellawell, the Government's former drugs czar who resigned when
the Government moved to change the law in 2004, strongly agreed,
although last week he worried that the apparent U-turn has come too
late. "Reclassifying cannabis now is too late as a generation of
young people have been led to believe it is a harmless substance.
This move is no more than window dressing to ease the conscience of
weak people who lacked the courage to prevent one of their own
causing the damage in the first place. Shame on them."

The national cannabis debate encompassed the highest levels of
government earlier this month when Ms Smith admitted that she had
broken the law by smoking the drug in her youth. Her statement
prompted similar confessions from nine fellow cabinet members. Ms
Smith said that clearer evidence about the dangers of cannabis use
since she was at university in the early 1980s was compelling and
young people would be obliged to listen when she urged them not to
try the drug, rather than follow her example.

Although the prevalence of skunk, which is routinely offered by
dealers instead of milder forms, means smoking can do users more harm
than a decade ago, government figures show that the cannabis use is
falling among young people. The number of 16- to 24-year-olds who
smoked cannabis in 2006 has fallen by a quarter since 1998 - the last
time the Government published its drug strategy. And among 11- to
15-year-olds cannabis use is also down: 10 per cent of pupils had
smoked cannabis last year, down from 13 per cent in 2003, 2002 and 2001.

Despite this, the number of people needing NHS treatment for
cannabis-related mental and behavioural disorders has risen sharply
in the last five years from 581 in 2001 to almost 1,000 last year,
lending weight to the argument that skunk is harming more users and
with greater severity.

Paul Corry, the director of public affairs at the mental health
charity Rethink, believes the debate should not focus on
reclassification, but instead urges the Government to "crack on with
the more important job of informing the public about the health implications".

Nevertheless, despite the mounting evidence that cannabis use causes
mental health problems - including The Lancet's publication last week
- - not everyone believes skunk poses long term health risks.

Professor Tim Kirkham, a psychologist at Liverpool University,
argued: "Cannabis has been used safely for many thousands of years,"
and says there have been "concerted efforts to demonise the drug's
use." Dr Trevor Turner, former vice president of the Royal College of
Psychiatrists, says: "I don't think it causes mental illness. I have
never seen a case of so-called cannabis psychosis."

Dame Ruth Runciman, the chair of UK Drug Policy Centre who set in
motion the downgrading of cannabis, disputes that the drug of today
is any different to the weed that Ms Smith would have toked back in
early 1980s.

"How do you know it's stronger?" she said, adding: "There is
indubitably some skunk that is stronger about the place, but the
evidence has been hugely exaggerated and does not support such an
alarmist view... Cannabis as Class C is exactly where it should be."

Skunk: The Drug at the Centre of the Controversy

Cannabis is more potent than ever, with Britain producing increasing
quantities of home-grown, hydroponic marijuana or skunk. This very
strong, force-grown form of cannabis is known for its powerful smell
- - hence its name - and its enhanced effects on the mind of the user.
It is often grown in nutrient-rich water under strong lights to
produce far more tetrahydrocannabidinol (THC) - the mind-altering
compound that gets users high - than regular cannabis, making it many
times stronger than conventional "grass" or resin.