About five years ago, Julie Lynn-Evans became aware that cannabis was not the mild and harmless drug that she had always thought it to be. Partly it was through having teenage children of her own and talking to other parents, and seeing how wiped out and catatonic kids could be after smoking "skunk", as the form of the drug now dominating the market is known. At the same time, she began to notice that a large proportion of the troubled adolescents she was seeing in her consulting room - all the boys, at least- were cannabis users. A psychotherapist with many years experience of working with teenagers, she suddenly saw links between their use of the drug and the problems that were bringing them to her, including paranoia, depression, lethargy, violence, school refusal, school exclusion and poor self-esteem. There was no scientific evidence she knew of to support her. But other psychiatrists she talked to had observed the same phenomenon and were arriving at the same conclusion.
Where there's smoke ...
When the government last year downgraded it to a class C drug, the message seemed pretty clear: cannabis is harmless. Since then, there has been mounting evidence of a link between the drug and mental illness. So is it safe to skin up? Blake Morrison reports
"I'm not an alarmist," she says, "nor a reactionary. In fact, I'd say I'm one of the most liberal people I know. But I am really worried. What my generation smoked as cannabis and what today's kids are smoking are completely different. This isn't some cosy, middle-class moral panic - we're talking about kids with knives, kids in trouble with the police, kids on lock-up wards and in psychiatric hospitals. I used to get just a trickle of cases - now I've a long waiting list of kids who have lost their way. And there's no doubt that skunk plays a large part in many of the sad stories I'm asked to disentangle. It's an incredibly dangerous drug."
Earlier this year, to make her point, she told a newspaper: "I would rather my daughter took heroin." Now she slightly regrets the sound bite - "a needle full of heroin is a pretty scary idea, too" - but she sticks by the point she was trying to make: that while heroin addiction is curable, the effects of skunk on some people are not. "Once psychosis has been triggered, the effects can be permanent. I have young kids who come to see me who only get by because they're on anti-psychotic drugs. And for a small percentage, there's no way back. They've lost control of their lives and we've lost them."
Lynn-Evans and I come from the same generation, one that hit adolescence in the 1960s or 70s. Aren't her anxieties precisely those which our parents expressed when we took drugs? "Fair point," she says. "It could be that I'm turning into a reactionary old goat. But the kids who come to see me don't seem to think so. And the research to back up my hunch is in place now. There's more and more of it every week, and all the studies show the same thing: that for a significant number of young people, smoking cannabis poses a risk; and the earlier you start smoking, the greater that risk will be."
When cannabis was downgraded from a class B to class C drug in January 2004, with police officers encouraged to adopt a softly-softly approach towards anyone caught in possession, it seemed the first steps towards decriminalisation had been taken. Many of us welcomed the move as a more realistic way of dealing with drug use. But in the past few weeks and months, a series of research studies and news reports has undermined cannabis's reputation for benignity - to the point that the home secretary, Charles Clarke, is said to be considering a reversal of the policy.
The idea of "reefer madness" is an old one and cannabis is still illegal in most western countries. None the less, it's hard to think of another drug that has enjoyed such a clean bill of health for so long. Herodotus first reported its positive effects on Scythian tribesmen circa 450BC: "[It] gives out such a vapour as no Grecian vapour bath can exceed; the Scyths, delighted, shout for joy." A report by the Indian Hemp Drugs Commission in 1894 found "no injurious effects on the mind ... even the excessive consumer of hemp drugs is ordinarily inoffensive". Likewise a Canadian Government Commission of Enquiry in 1972 noted "a quieting or tranquilising effect. No tendency towards aggression or violence." Cannabis has never been known to kill anyone: estimates suggest that you would have to eat at least 675 grams of resin in a sitting to endanger yourself. And though cannabis smoke contains many of the same toxins and carcinogens as tobacco smoke, the main focus until recently has been on the therapeutic effects of the drug - its role in easing the suffering of those with multiple sclerosis, arthritis and Aids. In 2002, there was even a move among women members of the trade union Unison to popularise it as a calorie-free alternative to wine or chocolate.
Since then, however, and particularly over the past 12 months, all the stories about cannabis have been negative. Much of the alarm is due to the fact that the drug is not the same as it used to be, and the very high content of active ingredient in skunk compared with more benign weed. Called tetrahydrocannabidinol or THC, it is the main psychoactive ingredient in cannabis, the bit that makes us high. Skunk tends to be grown hydroponically (without soil), indoors and without natural sunlight, and whereas 30 years ago an average joint contained about 10mg of THC, a joint of skunk today might contain as much as 300mg. Websites selling cannabis seeds emphasise their potency in a language that is the antithesis of hippy peace and love: "a true resin bomb"; "will have you on your knees begging for more"; "a killer skunk strain". One celebrated breed is called AK47, others bear names such as Guerrilla's Gusto, White Widow, Durban Poison, Paraliser (sic) and The Afflicted. For the dealers - and these online ads are pitched towards "professional cash croppers" - profits depend on being able to supply ever more mind-blowing stuff.
That cannabis can do your head in has been the message of several key scientific studies. One, carried out by Robin Murray, a consultant psychiatrist at the Maudsley hospital in south London, in conjunction with the University of Otago in New Zealand, followed a group of 750 adolescents over 15 years. Of those who had used cannabis three times or more by the age of 15, one in 10 had later been diagnosed as schizophrenic, compared with 3% of all other participants. Overall, people were four and a half times more likely to be schizophrenic at 26 if they smoked cannabis at 15.
Murray's research is backed up by his own observations of patients at the Maudsley, who are sometimes successfully treated for schizophrenia, then go out, begin smoking cannabis again and are readmitted. He does not deny that other factors come into play. But his scientific evidence - focusing both on a pleasure-enhancing or "reward" brain chemical called dopamine, which cannabis use accelerates, and on what some regard as the "predisposition" gene for schizophrenia - is reinforced by several others in the field. Among them is Jim van Os, a professor in the department of psychiatry and neuropsychology at Maastricht University, who last year published the results of a study in which 7,500 people were interviewed about their drug consumption: once again, regular consumers of cannabis were found to be more likely to develop psychosis.
A third study, carried out at the Karolinska Institute in Sweden by Professor Yasmin Hurd, has undermined the widely held belief that by the time children reach their teens their brains are almost fully formed and therefore as resistant to the effects of drug use as adult brains: her experiments with rats found "long-lasting physical changes" - damage would be another word. There have been further influential research studies (epidemiological, biochemical and genetic), including one dating back to 1987 that followed 50,000 Swedish conscripts over 15 years; it, too, links cannabis and schizophrenia. Where there is a history of schizophrenia in the family, the risk is particularly acute, and many teenagers will be unaware of having relatives with mental-health problems. Zerrin Atakan, of the National Psychosis Unit, summarises the findings: "Does cannabis trigger an earlier onset of psychosis in predisposed people? Yes. Does cannabis exacerbate the symptoms generally? Yes. Does cannabis use worsen the outcome and progress the illness? Yes."
In the past, studies of cannabis have reached wildly diverse conclusions. And some have frankly defied common sense - like the Australian and British studies which suggested that people with dope in their system make better drivers than those without. What is different about the new research is how quickly its findings have become widely accepted; for instance, the chief executive of Sane, Marjorie Wallace, has said that, "Far from being a relatively harmless recreational drug, for vulnerable teenagers the innocent spliff ... could trigger a journey of lifelong disintegration." The mental-health charity Mind's advisory pamphlet on cannabis details the symptoms it can induce - hallucinations, fantasies, voices, depersonalisation, loss of control, irrational panic and paranoia.
But more surprising voices have also endorsed the research, including liberals who perhaps never expected to find themselves lining up with the Daily Express and Daily Mail on the issue of drugs. In 1997, the Observer columnist Sue Arnold wrote a piece celebrating the wondrous powers of cannabis in restoring her sight, after a spliff temporarily alleviated her retinitis pigmentosa. Seven years later, she reported that her laissez-faire views had gone by the board after her son had a bad psychotic episode with skunk and spent six months in hospital. A more spectacular volte face has been that of Rosie Boycott, who as editor of the Independent on Sunday in 1997 led an influential campaign to legalise cannabis: if alcohol is a tiger, the paper declared, "then cannabis is a mouse. Everyone has probably known someone whose life - or family - has been blighted by alcohol, heroin or cocaine ... Certainly no one has ever been disfigured by a joint." By the summer of 2005, though, Boycott did know people whose lives and families had been blighted by cannabis; she made a television programme and wrote a long and detailed piece in the Daily Mail entitled The Cannabis Catastrophe that explained why "cannabis users today are playing russian roulette with their mental health".
Boycott's article also mentions three recent highly publicised cases in which the murderer or would-be murderer was a cannabis user: Richard Cazaly (whom police now accept stabbed Abigail Witchalls), Luke Mitchell (who killed his 14-year-old girlfriend Jodi Jones) and Mark Hobson (who murdered two sisters and an elderly couple) were all heavy users. Now even the palliative effects of cannabis are being challenged; this week, an inquest opened into the death of a 70-year-old women who had been treated with Sativex, a trial drug made of cannabinoid extracts. The reinvention of dope from cool drug to danger drug is almost complete.
Is the case against cannabis really that simple? No. The plant itself is complex, with more than 60 compounds and 400 chemicals, and so is the research - there are important differences of opinion about what it tells us. It is not just that the statistics do not seem to justify the widespread panic: current figures suggest that cannabis use increases the incidence of psychosis from 1% to 3% at most, and that the life-time incidence of schizophrenia per se remains at one in 100 (or 0.4% of population at any one time). There is also the vexed issue of causality. And what most of the research has so far established is correlation, not cause.
"If cannabis caused schizophrenia," says Trevor Turner, a consultant psychiatrist based in Hackney in east London, "the rate of incidence in countries where it's used more widely would be higher - but there's no evidence of that. Nor has the rate of schizophrenia increased in the UK, despite statistics showing that 50% of young people have tried it, compared with only 10% in 1970." When I mention Robin Murray's claim that in the area of south London where he works the rate of schizophrenia has doubled, Turner points to complicating factors including an immigrant, urban population (schizophrenia is always more common in cities and among immigrants) and the fact that methods for recognition are so much better these days.
"I'm a front-line psychiatrist with 100-150 new patients every year and I've never seen a case of cannabis psychosis," he says. "What cannabis does is bring out symptoms that were already there - it makes the illness more overt and triggers it to emerge earlier, but that's all. Just because B follows A doesn't mean that A has caused B; that's a classic therapeutic delusion. The truth is that cannabis affects different people differently. I have patients who say it makes them feel better, as well as being one of the few pleasures they have left."
John Macleod of the University of Birmingham is another sceptic. In May 2004 in the Lancet, he analysed 48 research studies on the alleged psychological and social harms of cannabis, concluding that two-thirds of them were of dubious methodology and that even the better ones failed to prove a causal relation. "It's chicken and egg, isn't it," says Colin Stewart, a drugs adviser at Release. "We're talking about a very messed-up generation of kids who are drawn to drugs as a way of coping, and if you've got problems already, smoking cannabis isn't going to help. But to blame cannabis for every mental-disorder is simplistic. We get worried parents calling all the time because their kids are going off the rails. If you do have a child with mental health problems it can be devastating. But sometimes what they're talking about is just hormones. 'My Johnny's not the same as he was when he was 13,' they say. Well, no, he wouldn't be. That's what's called being a teenager."
Is this climate of panic having an effect on people's cannabis habits? Yes and no. In my own peer group, hardly at all: these are people in their 40s and 50s who have been smoking the stuff for years and say that if it was going to affect them badly they would be in trouble by now. For them this is just another fashionable health scare, safely ignored. "I recognise the thing about cognitive impairment," one friend says. "If I'm playing Scrabble while I smoke, the words I come up with will get shorter and shorter. But it's also good for my aches and pains, and never gives me a hangover." Another friend is pleasantly vague: "What is skunk exactly? I'm not sure I know. I smoke every night with my partner - we giggle a lot, and it enhances our sex life. Weed is too much part of my life to want to change now, especially when it does me no harm."
Mark, who hit 30 last year, is less sanguine. "Out of all my friends, I'm the only one still smoking," he tells me. "Either their performance was suffering at work, or their girlfriends didn't like it [skunk has always been more of a boy thing], or they'd heard the stories about people flipping out and being sectioned, or had themselves had a bad experience of paranoia; drinking seemed the better option all of a sudden. And whereas five years ago you had to hunt for skunk, now - in London at least - it's finding a dealer who sells hash that's difficult. Every morning I see kids smoking it on their way to school, and that's worrying. If the stuff we had was the equivalent of beer, theirs is whisky and they're having it for breakfast."
Wyatt, a student I talked to, recently quit after smoking skunk for about four years. "It was ruining my relationship with my family, making me feel bad about myself, screwing up my education, stopping me getting jobs, turning me paranoid and reclusive, and costing me a lot of money. I realised all this before I quit, but I'd built up quite a dependency and it was only because several friends packed it in at the same time that I made the break. Even so, I worry about having done lasting damage to myself. People still don't know what the long-term effects will be, because most of the research dates back to a time before skunk was on the market."
Murray believes the scare stories of the past year or two are already having an impact: "There has been a dip in consumption, even though the legislation is now more liberal," he says. Atakan also thinks the message is getting through: "Quite a number of the patients who come to me have read or seen something in the media, or their parents have. But there's so much more we need to do, primarily in the area of education. I recently spoke about cannabis to some primary school kids and was amazed how familiar they were with the drug, what a normal part of their life it was, because their older siblings smoked it. And there's this misperception many teenagers have - in part because of the success of the anti-tobacco campaign in schools - that a spliff is a healthier option than a cigarette. If you're going to reach kids that age, you have to be creative."
One of the most creative ideas I heard came from Arnold Cragg, who compiled a report on cannabis and mental health for the Home Office and Department of Health last year. "Some young people who have smoked cannabis and got into difficulties still have a problem refusing offers of joints from friends," he says. "It would be easier and less damaging to their street cred if they could simply say, 'No I can't, I'm allergic to it,' rather as someone with a nut allergy avoids nuts. The point is that, just as people react differently to drinking alcohol, or sunbathing, or seasickness, so they react differently to cannabis. But that's not how most young people perceive it."
Cragg's report has never been published, perhaps because it was feared that with Charles Clarke looking again at drug classification, Cragg's conclusions would in some way muddy the waters. A planned Home Office leaflet giving advice about cannabis has not appeared either. Little wonder young people are getting a mixed message, or no message at all.
Interestingly (and it might come as a surprise to the Daily Mail), there is one point on which almost everyone I spoke to agrees: it would be much better if cannabis were legalised. At present, consumers cannot be sure about the strength of the stuff supplied by dealers. If they could buy it over the counter, the THC content clearly displayed like alcohol proof on a bottle, they would know what they were getting. Prohibitionist Jeremiahs warn that punters would inevitably go for the high-octane stuff, but the argument does not follow: given the choice, we do not all opt for brandy rather than beer. Meanwhile, few mental-health professionals see the point of criminalising already vulnerable people.
There are caveats. "I'd legalise normal dope, but turn skunk into class A," says Julie Lynn-Evans. "An almost impossible thing to do, I know, but it's the only way that makes sense unless you decriminalise the whole lot." Rosie Boycott says that if she was running the IoS campaign today, she would do it differently -"you couldn't put your hand on your heart and say this drug is safe" - but that what she now knows only makes legalisation even more important. "It is astonishing to me that substances that cause extreme harm are in the control of criminals whose only interest is financial gain."
Precise solutions differ, but what is encouraging is to see how much seeming opponents have in common. Ztakan believes that it is important to work with pro-cannabis lobbyists (the UK Cannabis Internet Activists carry a message from her on its website), while the pro-legalisation group Transform readily acknowledges that cannabis can pose a risk to a minority of users, but sees no need to punish the majority for whom it is safe. As Van Os says, highlighting risk is perfectly compatible with legalisation and allowing people to take control themselves.
All this seems admirably grown-up. But the chances of the present government taking any notice look minuscule. By all accounts, Blair wants cannabis to go back to being a class B drug. Nor is David Cameron, whose rumoured youthful experiment(s) with cannabis nearly became a leadership issue, likely to risk appearing "soft on drugs", however compelling the logic of decriminalisation. So the real psychotic traumas of a minority and the unfounded anxieties of the majority look set to continue, while Blair and Clarke tinker with classification and do nothing to sort out the mess.