Cannabis: Can it really drive you mad?

Two years after the law was relaxed, the nation's favourite recreational drug is to be reclassified. They say it is linked to psychosis, but can the odd spliff be that dangerous? Jeremy Laurance reports

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 pint has over the years spread way beyond its traditional student constituency to every corner of society. But two years after the 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, indicated last week that following the report from the the Advisory Council on the Misuse of Drugs, he is planning a U-turn on David Blunkett's 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?

Cannabis is the most widely used illegal drug in the UK, and the impression that it promises a risk-free high was increased by Mr Blunkett's move. But 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 institutions.

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 is stronger than it was a 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 exception.

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 16. 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 age.

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 per cent 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 per cent 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 Professor 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 increased."

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.

Professor Murray says that overall, results from a number of studies suggest that smoking cannabis raises 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 population.

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

Professor 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 Professor 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 Americans."

WEED OUT THE FACTS

3.6m: The estimated number of cannabis users in England and Wales - more than 10 per cent of the population

13,304: People convicted of cannabis possession in 2004.

11%: Of schoolchildren aged between 11 and 15 took cannabis in 2004, says the Home Office.

50,000: People took part in a Cardiff University study which found those who used cannabis more than 50 times before turning 18 were three times more likely to develop schizophrenia

'I would withdraw for days, lost and anxious'

After a 20-year habit, Lulu le Vay says cannabis is the worst drug of all

I smoked my first joint aged 13. The ritual in my family was to be "initiated" by an older brother by the fallen oak tree at the end of our rambling East Sussex garden. But in my case, one particular brother, a decade my senior, decided to pop my pot cherry in a club in north London. He produced a bag of weed that nearly knocked me out just by smelling it. It was a smell that to me, even at 13, was so familiar - a thick, juicy odour that had tumbled out from under various bedroom doors and windows along with wafts of George Benson and Stevie Wonder. I can't remember much of that night (no big surprise) but I know that to me, my older brothers were the coolest human beings on the planet. I finally felt accepted. Over the next few years I dabbled, but it was the dawn of acid house in the late 1980s that transformed me into a spliff-chugging monster. I tried just about anything, but smoking weed was a regular habit.

I smoked through my college years and the start of my career as a writer and music promoter. Smoking a spliff was as natural as putting the kettle on first thing, an act which was often followed by sparking up a cheeky one - before breakfast. But along with my blossoming career came a deterioration in my mental and physical health. At the time I would have never considered puffing a contributory factor to my increasing spells of depression, anxiety, and weight gain. Back then an entire weekend could be easily - and was often - consumed by watching Sopranos box sets in bed, washed down with a few kebabs and a drip of red wine and diet coke. Once, I got so high, I actually phoned the BBC Complaints Department to inform them that the audio on the television was completely out of lip synch. To me that was normal behaviour.

In the beginning, getting high acted as a blanket between me and the real world. Reality was smudged, that feeling of being knocked slightly out of the zone distracted me from having to deal with real life issues around me, and those of the past - I hadn't yet dealt with unresolved issues from a tempestuous upbringing. I would withdraw for days, lost and anxious - staring at the ceiling trying to work out what the fuck I was going to do with my life. It wasn't all bad, there were moments of genius - being stoned inspired some of the most creative feature ideas of my journalistic career to date. But over time, the depression and anxiety increased until I hit crisis point. I was a bleary-eyed, bloated, existential mess.

Smoking pot has become increasingly acceptable. Skinning up a joint to accompany an afternoon cuppa and a Hob Nob has become no knee-quaking big deal. Right now, thousands of young people - and some adults - are locked away in their bedrooms with a bag of skunk in one hand, and a remote control in the other - hypnotised by crap TV and hooked to the escapist antics of Playstation games. For some parents with a concern for their child's future, a dabbling in cocaine is a far more digestible alternative. "I'd rather my son take a more proactive, less habitual drug like cocaine, than lock himself away and play video games" says Roxanne Richardson, 35, who has a young son, and is expecting another. "It's so lazy. At least with pills and coke you're out and about doing something."

My older brothers not only enjoyed smoking dope, but hoodwinked our dear mother by cultivating and harvesting loads of it in the back garden. And they're still at it. The eldest, who is now almost 50, is still nurturing and smoking his stash with as much joie de vivre as he did when he was in his teens. His reclusive lifestyle and self-alienation from the rest of the family - not to mention lack of real ambition and aptitude to full-time work - is an obvious indicator of what the drug has done to his mental health. He is lost in his own world and has become a stranger.

The other brothers are also still pretty keen. One dips into his teenage son's stash when he's out of the house, and another once travelled all the way to Brixton tube station from the suburbs in pure desperation - all he ended up with was a bag of fresh lawn grass. Other people in my life haven't been so lucky. One friend suffered from such severe skunk-induced psychosis he threw his lodger up against his bedroom wall and put a carving knife to his neck. Yet in contrast, one close mate is able to smoke four pure skunk spliffs at breakfast before heading off on his weekly 10-mile run. Remarkable.

Hitting 30 and my father dying resulted in an epiphanal moment about what life was and where mine was going, and I made the decision to make the best of it, before it was too late. But I didn't sack off the spliffs intentionally, it just naturally happened. I swapped the late nights lost in a haze of anxiety for a new pair of trainers and an early morning run around the block. The permanent brain fog began to disappear and a year later I started training for the London Marathon. In time I realised that natural endorphins versus smoking marijuana was no contest.