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The use of cannabis by young people is currently clouded in a confusion that has nothing to do with the effects of the drug itself. Muddled messages over its legal status and effect on health have created uncertainty over exactly what risks people are taking when they indulge in the nation's favourite illicit substance.

Cannabis was reclassified on 29 January from a class B to class C controlled substance. This puts it in the same legal category as Valium and drastically reduces the penalties for possession (see box). The move came after the Advisory Council on the Misuse of Drugs concluded that "in terms of its inherent toxicity or harmfulness" cannabis could no longer compare with other class-B drugs such as the amphetamines.


However, on the day the reclassification was announced the government also launched a £1m media campaign stressing that cannabis remains illegal and that children and young people cannot expect the same leniency as adults from the police.

This was followed a few weeks later by prime minister Tony Blair telling the News of the World that head teachers would soon be given powers to randomly drug test their pupils and exclude those who proved positive or report them to the police. Under a hail of protest the government later back-tracked, acknowledging that such tests could only be carried out with pupils' and parents' consent.

Meanwhile, the British Medical Association, Royal College of Psychiatrists and mental health charities have been at pains to point out that the reclassification of cannabis should not be interpreted as giving the drug a clean bill of health.

"Chronic cannabis smoking increases the risk of heart disease, lung cancer, bronchitis and emphysema," says Dr Peter Maguire, deputy chairman of the BMA's board of science.

In particular there has been growing concern at evidence linking early cannabis use with the onset of psychotic illnesses such as schizophrenia.

According to a study by the Institute of Psychiatry, people who use cannabis before they are 15 are four times as likely as others to have a diagnosis of schizophrenia or a related condition at age 26.

Schizophrenia

The study also showed that young people who use cannabis before the age of 15 are more likely to develop schizophrenia than people who start using it between 15 and 18. "The earlier people start using cannabis the greater their risk for developing psychosis," says Dr Louise Arseneault of the Institute of Psychiatry and principal author of the paper.

The review was unable to establish whether cannabis was a direct cause of the psychosis or whether it simply acted as a trigger in already vulnerable young people. Not all adults with schizophrenia have used cannabis in adolescence and most cannabis users do not develop psychosis in adulthood, the study pointed out.

Nevertheless the authors estimate that if cannabis use could be eliminated within the population it would reduce the incidence of schizophrenia by about 8 per cent.

"Cannabis use among psychologically vulnerable young people should be strongly discouraged by parents, teachers and health practitioner," they conclude.

At current levels of popularity, however, the idea of eliminating cannabis use is ambitious. The most recent figures from the Department of Health estimate that nearly one in three 15 year olds have used cannabis in the past year. Clearly, for these young people, cannabis's class B status has failed to act as an effective deterrent.

Paul Corrie, head of policy and campaigns at mental health charity Rethink, acknowledges that education rather than criminalisation is probably the best way to deter young people from using cannabis. However, he feels that much of the information currently being released from the government is weighted too heavily towards the legal status of cannabis rather than its risks for mental health.


"We don't have a view on reclassification itself. To be honest cannabis is so widely available that anybody who would be using it probably is already. However, we do feel that the government has wasted an opportunity to really drive home the message on the risks of severe mental illness. There's been a lot of publicity from the government around the fact that cannabis is still illegal, but not very much on the risks to mental health."

Misinterpretation fears

Certainly, the government appears to be concerned that the reclassification of cannabis should not be misinterpreted as a step towards legalisation. Home Office drugs minister Caroline Flint has stressed the measures the government is taking to get the message across that cannabis remains illegal and that under-18s will still be arrested for possession.

"Using the radio ads alone we expect to reach 81 per cent of 15 to 17 year olds and 41 per cent of adults," she says. "This is just the beginning of an extensive campaign which will warn the public about the legal, health and social effects of cannabis use."

According to Andrew Bennett, director of the drugs information charity HIT, concern over cannabis's confused legal status is well placed.

"There's been confusion about the legal status of cannabis for about 18 months now, ever since they first started talking about reclassifying it," he says. "Some young people seem to think it's legal now or at least that they won't get busted for it."

In contrast, Bennett believes that the health risks of cannabis are well known by many of the young people who use it.

"HIT has done some research on this among cannabis users aged 15 to 50 and the results show that even among the youngest users, there is a fair proportion who are aware of the health risks," he says. "They tend to be most aware of the risk of respiratory illness, the tobacco-related problems and cancer. They are less aware of the risk of psychosis."

Bennett welcomes the reclassification of cannabis - "although I would go further" - and rejects the suggestion that the reduced legal penalties for possession are likely to result in an increased number of young people using the drug.

"For a large proportion of young people I don't think it will make much difference at all. If you look at other countries that have gone down this route, then there's no evidence that greater tolerance increases the use of cannabis. The Netherlands, for instance, has got 30 years of tolerance behind it and their young people are less likely to use cannabis than ours."

"All [prosecuting cannabis users] does is criminalise a huge swathe of young people and the effect of that can be far more devastating than cannabis."