Cannabis: the questions that remain unanswered
As the government orders another rethink on the drug, health editor Jo Revill and Martin Bright examine the range of evidence about its effectsJo Revill and Martin Bright
Sunday March 20, 2005
Observer

More than any other drug, cannabis and its effects have been studied and debated over the past 10 years. But serious questions remain as to who is most vulnerable to the damage which can be caused by regular use of the drug. On Friday, the Home Secretary, Charles Clarke, took the unprecedented step of ordering a review of the evidence about the health consequences of heavy cannabis use.

Clarke wrote to the Advisory Council on the Misuse of Drugs: 'I want to be clear what influence the evidence presented within these studies has on the overall assessment of the classification of cannabis.'

It was only 15 months ago that Clarke's predecessor, David Blunkett, reclassified cannabis from Class B to Class C, meaning it was no longer an arrestable offence to possess it. Cannabis is smoked by up to four million people in Britain every week, mostly on a casual basis.

Blunkett's move to downgrade cannabis was welcomed by many, including this newspaper, as a sign of a more grown-up attitude to drugs in general.

But for the past 10 years there has been evidence that the drug could have profoundly damaging effects on the brains of some users. The first study indicating it could be harmful came out of Sweden in the early Nineties and was disputed. Since then six major studies following users over a number of years have linked cannabis use to the development of psychotic symptoms. More evidence has since emerged that some people's genetic make-up may predispose them to be particularly vulnerable.

A study from New Zealand published earlier this month in the medical journal Addiction suggested 'a clear increase in rates of psychotic symptoms after the start of regular use'. The study, over 25 years, followed 1,055 people born in 1977.

Some fear the issue is being polarised. Professor David Fergusson, of the Christchurch School of Medicine and Health Sciences, and lead researcher of the New Zealand study, said debate was split between those who believe cannabis causes terrible harm and those who think it does not and should be legalised. 'I think the truth lies somewhere in the middle,' he added.

The other major study to have influenced Clarke's decision was by Professor Jim van Os at Maastricht University, in the Netherlands, in December. It concluded that use of the drug 'moderately increases' the risk of psychotic symptoms in young people but has 'a much stronger effect in those with evidence of predisposition for psychosis'.

There is a growing belief within the medical community that people who have a genetic risk of mental illness will be affected far more by cannabis than those who do not.

Cannabis resin contains the cannabinoid tetrahydrocannabinol, or THC, which produces a sense of euphoria and an apparent heightening of all the senses, especially vision. It slows the reflexes and gives an illusory sense of deep philosophical conviction, and sometimes the feeling of omniscience.

It does have a medical value; for people with multiple sclerosis or nerve damage it is known to ease the pain and attempts are under way to make a tablet form of the active compound which could be licensed for clinical use.

What worries doctors is the increase over the past 10 years in the availability of super-strength cannabis, known as skunk, which contains a high level of THC and is far more likely to trigger panic attacks, manic depression or a condition known as cannabis-induced psychosis.

But measuring how much this occurs is difficult because most people tend to lie when asked by doctors about their drug habits.

Many parents are also worried about the effect of stronger strains of cannabis. Observer radio critic Sue Arnold has described how her son, now 24, fell ill after taking cannabis.

'His first psychotic episode, as it's called in medical terms, was triggered by smoking skunk. Since then he has been on anti-psychotic medication more or less regularly.'

Arnold herself has smoked cannabis in the past because she found it helped her vision - she is partially sighted. But her son has been mentally ill for three years, diagnosed as a paranoid schizophrenic and sectioned under the Mental Health Act twice, making her very sceptical about its effects.

While evidence is growing that daily use of cannabis can have a damaging effect on the brain, studies also suggest that occasional use will not be harmful for most.

The question now is whether the advisory council, headed by eminent scientist Michael Rawlins, will suggest a reclassification to protect those whose genes leave them vulnerable to the drug. Given that cannabis can cause potentially irreversible chemical changes in the brain, the review is as essential for public protection as it is for political reasons.

Thanks for this article. There is such a controversial opinion on marijuana.

No retreat on cannabis
Leader
Tuesday March 22, 2005
Guardian

If ever a government had an early warning of one front it needs to defend in this election campaign, it is Labour's downgrading of cannabis. On the eve of ministers reclassifying cannabis from category B to the less harmful category C about 14 months ago, the ever-opportunistic Michael Howard declared a Conservative government would reverse it. He condemned the government's drugs strategy as "absurd", which serious policy-makers thought "shameless". Now, 14 months on, ministers are behaving "absurdly", not by referring new evidence about the drug to the Advisory Council on the Misuse of Drugs, but with their failure to set out the robust reasons behind their decision last year. Charles Clarke, the home secretary, asked the advisory council to say whether it would change their mind as a result of "emerging evidence" of a link between cannabis consumption and deteriorating mental health. It is unlikely that they will. The advisory council - along with the Royal College of Psychiatrists' working party and a Police Foundation's independent committee of inquiry - were all aware of the risks that cannabis posed to people vulnerable to mental illness when they made their recommendations to reclassify.

But certainly the two studies specifically mentioned by Mr Clarke should be referred to the council. The New Zealand study, according to Mr Clarke, "considered how regular cannabis use increased the risk of developing psychotic symptoms later in life". The conclusion of the Dutch study, published in the British Medical Journal three months ago, repeats findings of earlier research that "cannabis use moderately increases the risks of psychotic symptoms in young people but has a much stronger effect in those with evidence of predisposition for psychosis".

Much fuss has been aired in the red-top papers about these two studies, but with few quotes from the researchers. Yet the professor who led the New Zealand project told the New Zealand Herald: "These are not huge increases in risk and nor should they be, because cannabis is by no means the only thing that will determine if you suffer these symptoms." Professor Jim van Os, one of the authors of the Dutch study, was even more robust. He told the Guardian that the fact that cannabis could trigger psychosis in a small minority of people was a good reason to legalise it, not ban it. This would allow governments to promote advice and information and control more dangerous forms like skunk. Packets could carry how much THC, the most dangerous compound, the drug contained, along with how much CBD, the compound believed to provide beneficial effects.

Dame Ruth Runciman, who chaired the influential Police Foundation study, rightly reminded ministers that even with its downgrading, cannabis still carried one of the the highest penalties compared with the rest of Europe: up to two years in prison for possession and 14 years for trafficking. She went on: "A law which is credible to young people is more valuable to education than a law palpably at odds with their experience."

What was missing from the minister's response was a public reminder of why the drug was reclassified. It followed expert advice from professionals - medics, pharmacologists, police officers - not red-top papers. It freed a wide swathe of police officers to pursue serious drug barons, rather than trivial offenders. No wonder polls show 60% believe the drug should be decriminalised. If ministers needed to add a political message, they could have asked Mr Howard why he wanted to wage war on 50% of young people, ensure tens of thousands of them be given criminal records and some prison sentences, for an activity that more than 2 million of them engage in quite safely during the year.

'There has been huge confusion'
Charles Clarke is looking to the election with his review of drugs law
Tuesday March 22, 2005
Guardian

Sunday Telegraph Editorial, March 20
"Charles Clarke, the home secretary, is to order a review of the government's decision - passed just 15 months ago - to downgrade cannabis from a class B to a class C drug. The reason he cites is the emergence of scientific evidence of a link between smoking cannabis and the risk of psychosis ...

"The government is like one of those dreadfully confused parents who is slack one day and officious the next. On the one hand, it yearns to show that it is fashionably relaxed about people who enjoy the occasional joint; on the other it worries that they will puff themselves into a psychiatric ward ... Labour appears to believe it can be libertarian and authoritarian at the same time. We can only advise the government, therefore, to stay well away from cannabis: it's got enough identity problems already."

Kate Foster Scotland on Sunday, March 20


"There has been huge confusion over the drug ever since the former home secretary David Blunkett reclassified it last January to the status of steroids and anti-depressants, taking it from a class B to a class C drug. Now the legal status of cannabis, and those who use it, has been plunged into deeper chaos by Mr Blunkett's replacement, Mr Clarke, who ... has asked his independent advisers about reintroducing a higher classification in the light of new evidence about stronger forms of the drug leading to serious mental health problems ...

"Mr Blunkett's decision last year was hugely controversial ... Aside from the political ramifications there was general public bemusement, not least because the complicated new set of rules were not spelled out clearly enough ... If there is to be an about-turn on drugs, the government ... must make sure that the facts on cannabis are spelled out clearly."

Times Editorial, March 21


"Two forceful arguments were originally put forward in favour of reforming the old law on narcotics. The first concerned the balance of evidence of the harm associated with cannabis. The second related to the amount spent by the police in chasing people whose principal 'crime' was putting themselves at potential risk and who were otherwise law-abiding citizens ...

"If a fundamental review of the evidence implies that cannabis is considerably more of a threat than previously believed, the medical aspect of this debate will have to be awarded more weight than the impact of reclassification on policing. The strong suspicion, however, is that the medical debate will not be resolved so clearly ...

"Mr Clarke has kicked this controversy into the long grass. The review he has commissioned will not even start until almost a month after polling day. He should make it clear, none the less, when the issue re-emerges, that every implication of any attempt wholly or partly to reclassify cannabis will be examined before implementation."

Independent on Sunday Editorial, March 20


"It is well known that one side effect of cannabis is that it can make users paranoid and suspicious. You do not have to be stoned, however, to wonder about the home secretary's motives in asking for a review of the law on the drug ... It's the election, stupid. Mr Clarke is practising defensive politics ... He and the prime minister can block any charge that they are 'soft on drugs' by saying that the law is under review.

"In the past, the Independent on Sunday has called for cannabis to be legalised. But we are prepared to suspend our judgment ... If cannabis use can be shown to be a definite and significant cause of mental health problems, the case for legalisation may have to be reconsidered. What is required is a thorough examination of the evidence ... It is wrong, however, that this review should be coloured by the superficial imperatives of an election campaign."

Peter Hitchens Mail on Sunday, March 20


"Do not be doped by the government's attempt to seem tough on drugs. Once the election is over, Labour - and its pro-cannabis friends in the Useless Tory party - will return to their policy of appeasement and weakness ...

"Britain's establishment, of both parties, has been penetrated by drug propaganda even more effectively than it was once penetrated by the KGB. Far too many of the political class smoked dope in their college days and beyond. Many more permit their children to do so.

"Being well-off and protected they have little idea of the devastation wrought on poor areas by their appeasement, and they are determined to continue with this plan. When the election comes, ask your candidates to give a clear written commitment to vote to recriminalise cannabis. And watch them wriggle."

Raj Persaud Independent, March 21


"Marijuana use in early adolescence is associated with the strongest schizophrenic effect, so perhaps what is really worrying Mr Clarke, quite rightly, is that we're sitting on schizophrenia time bomb, which will blow up in our faces as young cannabis users grow up into psychotic adults ...

"If it is young adults who are most at risk ... then Mr Clarke should surely be concentrating his efforts primarily on delaying the age at which cannabis is first used."