Skunk: How the 'safe' drug of choice for the hippy generation became a serious health hazard

Lucy Farmer was 14 when she first tried cannabis. It was easy to get. Most of her friends had access to supplies where she was growing up in Buckinghamshire . She never even had to pay for it at first.

"At first, it didn't really seem a problem," she said yesterday. "But you get paranoid and lethargic and are not motivated to do anything at all. There was so much of it around."

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Then came the downside. "The paranoia made me react to my parents in an aggressive way and we had huge rows. You think everyone's talking about you, laughing at you, things like that. You feel so negative, and are in a downward spiral.

"There were times when I'd wake up in the morning and not be able to go to school. You just don't see the point and nothing is important to you. Your memory is mushed and your brain will not function."

Yet Lucy was not smoking the traditional cannabis beloved and introduced en masse by Britain's Sixties youth. It was skunk - a form of cannabis so powerful that experts are warning it can be 25 times more powerful than the cannabis used by previous generations. Growing new strains of cannabis under ultra-violet lights, dealers have been able to intensify the quantity of the chemical tetrahydrocannabidinol (THC) - a psycho-active compound that disrupts brain activity and distorts sensory perceptions. In short, the part that gets you high. But feelings of euphoria and relaxation can be soured by paranoia and memory loss. Significantly, teenagers whose brains are still developing are more sensitive to the sudden rush of THC into the brain.

Today record numbers of young people are in treatment programmes for skunk abuse and hospital admissions due to the drug are at their highest ever.

An increase in the strength of the drug and widespread use among Britain's teenagers has the potential to be a disaster, according to experts, who say that the young are at most risk of developing psychosis and schizophrenia.

A boom in the amount of super-strength cannabis being used by the estimated one and a half million Britons who smoke it each year has been mirrored by a massive rise in people suffering from mental health problems because of it. Figures from the NHS National Treatment Agency show that more than 22,000 cannabis users are in drug treatment programmes - almost half of whom are under 18. Compare that to Department of Health figures showing 1,660 cannabis users entering treatment programmes in the six months ending March 1997. In addition, the overall proportion of cannabis users of the total who are in treatment for drug problems has shot up from 6 per cent to 12 per cent over the past decade.

The number of people having to go to NHS hospitals suffering from cannabis-related mental and behavioural disorders has also risen sharply in last five years - from 581 in 2001 to almost 1,000 last year.

The scale of the problem has prompted calls by doctors, politicians and addicts for a rethink on the way we view cannabis, after a succession of reports have stated that it is less harmful than alcohol and tobacco. A new independent UK drug policy commission, chaired by Dame Ruth Runciman is being launched next month, and will call for a total rethink of the government's approach.

"Society has seriously underestimated how dangerous cannabis really is," says Professor Neil McKeganey, from Glasgow University's Centre for Drug Misuse Research. "I think we are faced with a generation blighted by the effects of cannabis use."

A cannabis joint today may contain 10 to 20 times more THC than the equivalent joint in the 1970s. A decade ago only 11 per cent of cannabis sold in the UK was grown here but now the figure has passed 60 per cent. And while the strength has increased, the price has dropped. Cannabis now sells for £43 per ounce on average, a big drop from the 1994 average price of £120 per ounce.

Robin Murray, professor of psychiatry at the Institute of Psychiatry in London, says that one-quarter of people are particularly at risk, having a five times higher risk of psychosis if they smoke cannabis. The drug is known to increase the production of dopamine in the brain, an excess of which produces the hallucinations characteristic of schizophrenia.

"The people we are seeing who are now in their twenties started using cannabis eight to 10 years ago," he says. "But the people now starting are starting on skunk. The number of people taking cannabis may not be rising but what people are taking is much more powerful - so there is a question of whether a few years on we may see more people getting ill as a consequence of that. We'll just have to wait and see."

Research to be published in this week's Lancet will show how cannabis is more dangerous than LSD and ecstasy. Experts analysed 20 substances for addictiveness, social harm and physical damage. The results, which will show many illegal drugs being less harmful than alcohol and tobacco, will increase the pressure on the Home Office to reform the existing ABC system of classification.

This comes just months after Antonio Maria Costa, the head of the UN's anti-drugs office, said: "The harmful characteristics of cannabis are no longer that different from those of other plant-based drugs such as cocaine and heroin."

Researchers at the Institute of Psychiatry are looking at the relationship between the active ingredients of cannabis and whether it causes psychosis by increasing dopamine levels in the brain. Fifteen patients are involved in the study, where they are given the drug and then have their brains scanned. Initial findings show that those given THC show higher levels of brain dopamine than those who have a placebo.

But others 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. Michael Linnell, the director of communications for the drugs charity Lifeline, argues: "No drug use is completely safe and yet despite the anti-cannabis propaganda on the telly and the distortion of the truth in the press, cannabis is and remains by far the safest drug on the planet."

In January 2004, when David Blunkett was Home Secretary, cannabis was downgraded from class B to class C, meaning that possession of small quantities of the drug was no longer an arrestable offence. The decision was taken on the recommendation of the Advisory Council on the Misuse of Drugs.

But last month Superintendent Leroy Logan, the deputy borough commander in Hackney, east London, said reclassification of the drug had led to "extensive and expansive" use among youngsters, increasing mental health problems and triggering a "paranoid mistrust" of the police and anyone in authority.

A "positive arrest policy" in central Brixton has resulted in hundreds of arrests since December 2005, and police claim to have seen a 35 per cent reduction in the crime rate in the area. But one chief inspector, who spoke under condition of anonymity, admits that they are struggling to control the problem. "There's still a widespread public misconception that cannabis is legal now and it makes our life very difficult. Skunk is a dangerous drug. This is a huge social problem and we're like the doctors treating the symptoms."

Justin Smith, from Brixton, was 13 when he tried skunk for the first time. He ended up skipping school and stealing to fund his £70-a-week habit, "I was just lying around in my house, just going out to find ways to get the money to smoke skunk. I used to steal to fund my use and this went on for a year and a half."

Now 19, Justin remembers how he became ill after chain smoking joints: "I'd been smoking so much that I threw up, had a terrible headache and lay paralysed for hours until I felt better. Sometimes I'd feel paranoid and keep looking around and thinking people were following me. Every day you think people are talking about you and are against you. I've seen people that have suffered on it talking to themselves out in the street like they are mad - laughing to themselves and everything."

He was helped to kick his habit by counsellors at a local project run by the charity Turning Point and is now on a business studies course. "I stopped a year ago. It was hard because it is addictive, but not like a cocaine addiction - it's more of a mental addiction."

Concern over the dangers of skunk has grown following a spate of murders and brutal assaults in recent years where cannabis psychosis has been cited as a factor. The latest example came last week, when a court heard how an addiction to skunk had exacerbated feelings of extreme paranoia that resulted in Thomas Palmer, an 18-year-old from Wokingham, Berkshire, stabbing two friends to death.

Mental health campaigners are now calling for action. Marjorie Wallace, the chief executive of the charity Sane, said: "Every day there is new evidence of the links between cannabis use and serious mental illness. A recent study showed that eight out of 10 of those experiencing first-episode psychiatric disorders were heavy users of the drug, another that they were four times more likely to develop schizophrenia. We need to give clear direction to young people and their families, to teachers and the police, that the drug is illegal and proven to be dangerous to a significant number of people."

But Richard Kramer, the director of policy at Turning Point, says cannabis is just one of the factors that can exacerbate mental health problems in vulnerable people. "We need clear, targeted education and prevention campaigns tailored to the most vulnerable groups, particularly those vulnerable to mental ill health and those who work with them. It is through such evidence-driven public health responses that we can best tackle the harms associated with cannabis."

Now 18 and studying for her A levels, Lucy has been seeing a counsellor from the drugs charity Addaction since she was 16. She says that many of her peers are complacent about cannabis. She warns: "People just don't see it as a problem, but it catches up on you. The truth is - you don't realise until it's too late."

Cannabis timeline

From a Hindu sacred text to the 'IoS' campaign:

1200-800BC: Cannabis is mentioned in Hindu text Atharvaveda as one of the sacred plants of India.

430BC: Herodotus reports on both ritual and recreational use of cannabis by the Scythians.

AD1378: The Ottoman Emir Soudoun Scheikhouni issues edict against the eating of hashish.

1798: Napoleon discovers the habitual hashish use among Egyptians and bans it. Returning soldiers bring the tradition home with them.

1830s: Queen Victoria is prescribed cannabis by her doctor to relieve period pain.

1928: Cannabis made illegal in the UK.

1968: The Wootton report into cannabis concludes: "There is no evidence that this activity is... producing in otherwise normal people conditions of dependence or psychosis requiring medical treatment."

1971: Cannabis classified as a class B drug: illegal to grow, produce, possess or supply it.

1997: Independent on Sunday launches a campaign for its decriminalisation.

1998: 16,000 march in London in support of IoS campaign. House of Lords recommends that doctors be allowed to prescribe the drug.

2001: The Advisory Council on the Misuse of Drugs (ACMD) says: "The mental health effects of cannabis are real and significant."

2004: Cannabis is reclassified from a class B to a class C drug. Possession illegal, but not an arrestable offence.

2005: ACMD asked to re-examine scientific evidence linking cannabis use in at-risk adolescents to mental health problems.

The 'IoS' test

From cannabis to skunk: facts and figures behind the spread of a class C drug

Cannabis is stronger than ever, with Britain swamped with home-grown skunk. The Forensic Science Service says that in the early Nineties cannabis would contain around 1 per cent tetrahydrocannabidinol (THC), the mind-altering compound, but can now have up to 25 per cent.

Tests on home-grown skunk acquired on the streets of London on Friday showed that one sample had a 9 per cent level of THC. That's low by today's standards but still double the strength of cannabis resin.

60+ per cent of cannabis consumed in Britain is home-grown

21 per cent of 16- to 24-year-olds have taken cannabis in the past year

25,000 schizophrenics could have avoided the illness if they had not used cannabis

12 per cent of children aged 11-15 have taken cannabis

9 million+ Britons aged 16-59 have used cannabis

£1billion+ is spent on the drug each year

9,600 under-18s are in treatment for cannabis problems