CANNABIS LINK TO PSYCHOSIS DEPENDS ON AGE

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CANNABIS LINK TO PSYCHOSIS DEPENDS ON AGE OF FIRST USE


Half of regular smokers of cannabis who are psychologically vulnerable to its effects may end up needing treatment for psychosis, scientists said yesterday.


Up to 10 per cent of the adult population, almost four million people, has a tendency to paranoid thoughts or grandiose ideas and may be tipped into psychotic delusions by the effects of the drug, they said.


A four-year study of 2,437 people aged 14 to 24 found that of those who smoked cannabis regularly and had a pre-existing risk of psychosis, 50 per cent developed psychotic symptoms over the period.


This was twice the rate among those who did not use cannabis and more than three times higher than among those who were neither vulnerable nor took the drug.


Five previous studies have shown a link between cannabis and psychosis but this is the first to quantify the risk in psychologically vulnerable individuals.


International experts meeting in London today will discuss the evidence at a conference on cannabis and health organised by the Institute of Psychiatry.


Robin Murray, a professor of psychiatry at the institute, said the popularity of cannabis combined with its increasing strength and the earlier age at which people started smoking were a cause for concern.


Comparing the rising toll of mental illness caused by cannabis to the epidemic of heart disease, he said: "We know lack of exercise and obesity are precursors for heart attacks. Now we are learning the precursors of psychosis."


Cannabis is the third most popular recreational drug after alcohol and tobacco, and Professor Murray said there was a question as to why more people were not psychotic. "It may be to do with how early you start.


The earlier it is, the greater the risk," he said.


Research in Australia shows that the average age at which people start smoking cannabis has come down since the 1970s from the early 20s to the mid-teens. In the Netherlands, it is 13 to 14, and in the UK it is unofficially estimated at 15 to 16.


Last week, figures showed that two in five 15-year-olds in the UK had tried cannabis - more than anywhere else in Europe. Zerrin Atakan of the National Psychosis Unit at the Maudsley hospital in south London said that the earlier people started using cannabis the more likely they were to become dependent on it. "If you smoke cannabis before 17, imaging studies show structural changes in the brain."


Studies of pregnant women who smoked cannabis showed changes in the brains of their children in later life, she said.


For the study, in the online version of the British Medical Journal, Jim van Os of Maastricht University and colleagues followed 2,437 young people from Germany.


Marjorie Wallace, the chief executive of the mental health charity Sane, said: "Britain's position as the cannabis capital of Europe could have hidden and disturbing consequences."


HEALTH BENEFITS


* Cannabis has been called the "aspirin" of the 21st century with evidence that its compounds may protect the brain against the effects of ageing.


* The world's largest study of the medical effects of cannabis reported in November last year that it could reduce pain and improve the lives of people with multiple sclerosis.


* Like alcohol, in moderation the drug promotes relaxation and enjoyment which are beneficial for human health.


HEALTH RISKS


* Regular cannabis smoking is associated with an increased risk of schizophrenia and depression.


* Up to 80 per cent of new cases of psychosis seen in psychiatric hospitals are triggered by cannabis abuse.


* Smoking three joints a day causes the same damage to the lungs as 20 cigarettes.


* The drug distorts perception, affects short-term memory and may cause hallucinations.


* Habitual users suffer from de-motivation.

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CANNABIS BACK IN THE SPOTLIGHT


The debate about the effects of cannabis will be reignited today by new research which warns it could cause future health problems for certain young users.


Supporters of the drug claim it is non-addictive, has proven pain-relief qualities and does not cause people to misbehave and commit public order offences.


But medical professionals and other bodies have cited various studies linking it to depression, lung cancer, amnesia and panic attacks.


The new research found frequent use of cannabis during adolescence and early adulthood increased the risk of users suffering psychotic symptoms in later life.


The German study, involving almost 2,500 young people aged 14 to 24, discovered that the risk of developing symptoms was much higher in young people who already had a pre-existing vulnerability to psychosis.


In January cannabis was reclassified from a class B to a class C drug ranking it alongside bodybuilding steroids and some anti-depressants.


Some organisations and politicians criticised the move but at the time Home Secretary David Blunkett said the change in the law was necessary to enable police to spend more time tackling class A drugs such as heroin and crack cocaine, which cause the most harm and trigger far more crime.


A spokeswoman for DrugScope, a leading independent centre of expertise on drugs, said the organisation agreed with the reclassification.


"Evidence didn't show it was as harmful as other class B drugs and most of the experts agreed it should be Class C."


But she said that the reclassification had confused some of the public and stressed it was still illegal and potentially still harmful.


She added that the new research made it even more important to give young people information about the effects of all drugs.


"The bjust say no' drugs campaign was very high profile, but a lot of the evidence has shown shock tactics don't work well with young people, they respond better to factual information," she said.


"Let them make the decision themselves rather than being told bdon't take drugs, drugs are bad'.


She added: "People can become psychologically addicted to anything. If someone feels something makes them feel better or not, they could crave it.


"There's no evidence of a physical dependence with cannabis use, but regular users can rely on cannabis to get them through the day."


Discussing the positive benefits of certain outlawed substances she said:


"If illegal drugs can be used to relieve suffering, that's got to be a good thing."


The spokeswoman highlighted an ongoing US study where Ecstasy is being used to treat post traumatic stress disorder, and a spray derived from cannabis is being developed to treat arthritis and Multiple Sclerosis sufferers.


Eye surgeons also use a gel during operations which contains traces of cocaine, she said.


A Multiple Sclerosis Society spokesman said it did not support the smoking of raw cannabis only treatments derived from the drug.


"Many people with MS have alot of anecdotal evidence cannabis can alleviate symptoms," he said. "Our stance has always been we must have properly controlled trials to establish the safety and efficacy of a (cannabis


derived) drug."


Steve Barker, a spokesman for the Campaign to Legalise Cannabis, said earlier this year that the drug causes problems in only 5% of the estimated


3.2 million people who use it in the UK.


He explained that in those rare cases where the drug does have an unfortunate side effect on people's personalities, they usually just stop taking it.


"It's not an addictive drug -- it can be habit forming but it isn't addictive," he said. "If people don't like it, they usually just stop.


Those users with psychological problems often have these problems anyway, so the drug has nothing to do with their condition."


Mr Barker also denies that cannabis has any long term health dangers and that an increased use of the drug could cause a major headache for the NHS in the future.


"Cannabis has been with us for 5,000 years in the Far East and there has been no particular problems emerging there of lung cancer.


"It has many positive effects. It doesn't cause public disorder and misbehaviour like alcohol and it's not addictive -- people can take it or leave it.


"Medically speaking, it can be twice as effective as any painkiller for people suffering from chronic pains and aches."