The dangers of cannabis use are back on the front pages thanks to a report just published in The Lancet from a team led by Theresa Moore & Dr Stanley Zammit. From their meta-analysis of 35 studies from around the world, Moore & Zammit inferred that any use of cannabis – which means even taking the drug just once – was associated with a 41% greater risk of experiencing some form of psychosis – and possibly even developing full-blown Schizophrenia. People who smoked the most cannabis were the most likely to suffer a psychotic breakdown; for frequent users, the risk rose to between 50% and 200%.
Overall, cannabis could be to blame for one in seven cases of Schizophrenia and other life-shattering mental illness. With up to 40% of teenagers and young adults in the UK believed to have tried cannabis, the researchers estimated that the drug could be behind 14% of cases of Schizophrenia and other psychotic illnesses.
Perhaps fortuitiously Gordon Brown announced on 18 July that the status of cannabis was to be considered as part of a wide-ranging drugs review commissioned by Home Secretary Jacqui Smith.
The Brown-Smith move was initiated a week after former Tory Party leader Iain Duncan Smith called for reclassification of cannabis from ‘C’ back to ‘B’ in the ‘Breakthrough Britain’ report of his policy group on social breakdown. Duncan Smith’s call was trailed and endorsed several days before the report’s publication by current Tory leader David Cameron.
The basis of Duncan Smith’s call was the already-large body of evidence linking the development of various psychoses – especially the onset of Schizophrenia – to the use of cannabis. However, Cameron focussed more specifically on ‘Skunk’, the genetically-modified development of ‘the weed’ containing approximately 3 times the amount of the active ingredient THC as ‘standard’ cannabis.
To some extent, in differentiating between standard cannabis and Skunk, Cameron was following the lead of the Independent on Sunday (IoS) newspaper which campaigned right up to and beyond then-Home Secretary David Blunkett’s 2004 reclassification for the complete decriminilisation of the use, storage and selling of cannabis. (The IoS has been one of the most prominent pro-cannabis voices in recent years and the paper’s influence amongst leading thinkers and parliamentarians on the issue is thoght to have been significant.)
However, in ordering a review of the classification of cannabis per se, Gordon Brown is treating all varieties of the drug as potentially warranting a more ‘dangerous’ classification.
As evidence has grown dramatically in the past few years of just how dangerous cannabis can be, so the likes of the IoS have been caught on the backfoot, overtly supporting the legalisation of a truly dangerous drug. It, therefore, suits them to draw a huge distinction between ‘standard’ cannabis and Skunk; the IoS argument is that it only campaigned for the ‘more or less harmless’ standard cannabis and the paper is totally against the use and distribution of Skunk.
As regards David Cameron’s own record on cannabis, it may well suit his agenda to follow the IoS distinction between standard cannabis and Skunk. He has all but admitted that he has used the drug himself by refusing to deny reports this February that he had been punished for smoking cannabis during his schoolhood at Eton; his office have also allowed stories to circulate that he was an occasional user at university. Only the month before (January 2007), the Tory leader had said publicly he opposed making cannabis legal but would be “relaxed” about legalising it for medicinal use if there was evidence of health benefits.
Hopefully the rash of Government ministers who have admitted recently to indulging in mild cannabis use during their younger days - including Alistair Darling, Ruth Kelly, Hazel Blears, John Hutton, Yvette Cooper and Jacqui Smith herself – will lessen the potential impact on political careers of *owning up* and this will enable a more mature debate on the issue.
Unfortunately many, many people have been caught in the trap the IoS and Cameron have found themselves in. For decades users and research scientists have said that cannabis was less harmful than alcohol and tobacco and, therefore, the argument against legalisation on health grounds simply didn’t stand up. How now do the politicians who supported such propositions reconcile their ‘service for the public good’ with their support for a drug some increasingly consider as dangerous as heroin or cocaine…?
The Skunk-’Standard Cannabis’ Fallacy
While there is no doubt that Skunk is a much more potent drug than standard cannabis, to draw such a distinction between the two varieties is at best disingenuous. Moore & Dammit certainly do not let standard cannabis off the hook and the science appears not to support such a distinction – at least in terms of the serious long term psychological effects.
Zammit personally led an earlier study, published in 2002, which looked at 50,000 Swedish conscripts from 1970 through to 1996. Those who had tried cannabis by the time they were 18 were 2.4 times more likely to receive a diagnosis of Schizophrenia. Those who had used cannabis more than 50 times had 6 times the usual risk of developing Schizophrenia. Zammit and his colleagues then estimated that 13% of Schizophrenia cases could be averted if all cannabis use were prevented.
Another study of almost 5,000 subjects in the Netherlands replicated the findings, and also found that cannabis users were more likely to be diagnosed with Schizophrenia during the study’s three-year follow-up period. Other studies suggested that subjects who used cannabis in their early teens were more likely to be diagnosed with Schizophrenia by their mid-20s.
In 2005 Netherlands researchers reviewed five studies and concluded that the use of cannabis approximately doubles the risk of developing Schizophrenia. Because the studies excluded anyone with a history of psychosis and controlled for the use of other drugs, they were “able to show the specific effects of cannabis”.
Also in 2005 research by Professor Robin Murray of the London Institute of Psychiatry – eg: DiForti & Murray – found that those who smoked cannabis regularly at 18 were 1.6 times more likely to suffer serious psychiatric problems, including Schizophrenia, by their mid-20s. For those who were regular users by 15, the risk of mental illness by the age of 26 was 4.5 times greater than normal.
Further Dutch, German and New Zealand studies have all found a relationship between regular cannabis use and psychosis, with heavy cannabis users doubling or tripling their risk of psychosis.
Critically a Department of Health spokesman summed up much of the emerging evidence in January 2005 thus: “There is medical clinical evidence now that there is an important causal factor between cannabis use and schizophrenia – not the only factor, but an important causal factor. That is the common consensus among the medical fraternity.”
Clearly, while there are minor variations in the percentages of risk, ‘standard’ cannabis is a very dangerous drug. Compared to Skunk, it isn’t at all harmless in the way pro-cannabis lobbyists like the IoS have suggested. It is simply that Skunk is a genetically-engineered more powerful version of a naturally-dangerous drug. Robin Murray, in commenting on the Moore-Zammit findings, possibly put it best: “My own experiences suggest to me that the risk with Skunk is higher. Therefore their estimate that 14% of cases of Schizophrenia in the UK are due to cannabis is now probably an understatement.”
Why does smoking cannabis cause Schizophrenia in some but not others?
Irving Gottesman’s 1991 largescale study is generally taken as the ‘gold standard’ for evidence that a substantial number of people have a genetic predisposition to develop Schizophrenia. He found a concordance rate of 48% for monozygotic twins – in other words, if one identical twin develops the illness, there is a 48% likelihood the other will - reducing down through 17% for dizygotic (non-identical) twins), 6% for half-siblings and 2% for the nephew/niece-aunt/uncle relationship, set against the 1% risk of developing the illness in the general population. So, basically the more genes you share with someone with Schizophrenia – ‘genetic relatedness’ - the more likely you are to develop the illness. Genetic predisposition to develop a very serious illness is a pretty scary proposition. However, it doesn’t mean that having a genetic predisosition automatically means you will develop the illness. It’s an example of the Diathesis-Stress model; in almost all such cases, it will need a damaging lifestyle or significant ’life event’ to trigger the onset of the illness.
For people with the genetic predisposition, smoking cannabis can be that trigger.
People without the genetic predisposition may get away with prolonged heavy use of cannabis without developing a psychosis.
So how do you know if you’ve got the genetic predisposition? Since the scientists have yet to isolate the gene(s) responsible, they can’t test for it. Clearly, if you’ve a close relative who has or has had pschotic episodes, you’re at risk. However, there being no apparent mental illness in the family is no guarantee that someone doesn’t have the genetic predisposition since the predisposition can be passed on through several generations via recessive genes without it being obvious.
If someone is high in the Psychoticism Dimension of Temperament,, then it might be logical to assume that person (usually male) is more at risk. However, for all there being some similarities in the behaviour of psychotics and those very high in Psychoticism, Hans Eysenck – Eysenck & Eysenck, 1976 – went to great lengths to emphasise that Psychoticism and psychosis are not the same thing.
From the research we considered earlier, it seems that using cannabis during adolescence may be a significant influencing factor. (The shortest development history on record so far is of a boy who started smokin the drug at 14 and was a full-blown schizophrenic by 17.)
The results of a 2007 study by Xiaobo Li et al at the Albert Einstein College of Medicine in New York may have found a degree of explanation for this. They found that heavy use of cannabis caused the same type of abnormalities in certain areas of the brain as were found in the brains of people with Schizophrenia, and these abnormalities were the most pronounced in schizophrenics subjects who regularly smoked cannabis.
The abnormalities occur in a brain pathway related to language and auditory functions which is still developing during adolescence.
Thus if a young person is genetically at risk for Schizophrenia, the research suggests the use of cannabis can cause the same kind of damage the Schizophrenia would cause, which could bring on the illness when it might otherwise have not have emerged, cause earlier onset, and/or worsen the condition.
The ‘Harm’ Fallacy
Although Gordon Brown is said to have “a personal instinct” that cannabis should be reclassified back to ‘C’, there is no guarantee that will happen. It certainly didn’t when then-Home Secretary Charles Clarke first reviewed predecesser David Blunkett’s 2004 decision in January 2006.
However, Clarke’s decision was influenced substantially by a report from the Advisory Council on the Misuse of Drugs which found alcohol (significantly so) and tobacco to be more harmful than cannabis. However, the Council’s findings related primarily to 3 classes of harm: physical harm, dependence and social harm. What they don’t appear to have considered (at least in sufficient depth) is the nature and depth of psychological harm.
There simply is no ‘cure’ for Schizophrenia. It is a serious and debilitating illness, with nearly a third of sufferers deteriorating progressively until they require full-time care and supervision. (The archetypal insane!) According to a 2004 study led by Delbert Robinson & Margaret Woerner, just 13.7% of diagnosed sufferers make an effective recovery. (However, since the illness is not well understood – there is a growing body of professional opinion that we should revert to Eugene Bleuler’s original 1908 proposition that the schizophrenias (plural) were a group of distinct psychiatric illnesses with some key similarities – it is difficult to be precise about what consitutes ‘recovery’.) The majority of sufferers will require a lifetime of managing the illness via medication and/or psychotherapy.
While the problems caused by alcohol misuse and tobacco use should never be estimated, it is surely a fallacy to say they are more harmful than cannabis. Even the argument about scale of use is becoming flawed. While the level of alcohol misuse is rising, tobacco use is continuing to fall while the rate of cannabis use, especially amongst teenagers, is on the rise.
In 2005 some 10,000 11-17-year-olds required medical treatment of some kind as a result of cannabis use. As researcher John Macleod told The Times in March this year: “…the number of cases of Schizophrenia will increase significantly in line with increased use of the drug.” No wonder that paper concluded we are sitting on a ‘cannabis timebomb’.
Should Cannabis be reclassified to ‘B’?
The Association of Chief Police Officers responded with some dismay to Gordon Brown’s 18 July announcement for all the reasons they lobbied for the original reclassification in 2004 – ie: large amonts of resources wasted on chasing smalltime perpetrators of what the general public largely percieved as a ‘non-crime’. (It is worth stating that there have been a notable minority of senior police officers who have consistenly disagreed with ACPO’s position.)
Which is where the views of Paul Corry, the public affairs director of Rethink,show us at least some of the way forward. (Rethink is a mental health charity which, amongst many other worthwhile activities, has campaigned vociferously for more research into establishing the causes of mental illnesses. In particular, it has campaigned for research into the effects of cannabis use on mental health.)
Corry wants education in schools about the dangers of cannabis use, directed from the Department of Education & Skills (DfES) so programmes are mandatory. Cleverly, he also wants young people who have suffered mental health problems as a result of cannabis use to be a key part of delivering the programmes on the grounds that teenagers are more likely to listen to other young people than teachers and police officers.
On an annecdotal note, I can certainly see Corry’s point. In teaching a class of disaffected Year 9s (the 14-year-olds) recently, I overheard 2 students discussing ‘blow’. When I asked them if they knew anything about Schizophrenia, one of them said he had an uncle with it. When I explained the link between cannabis use and Schizophrenia, they (and their mates!) wanted to know more.
In their kinds of communities (traditional working class/former mining), where the traditions and the superstitions associated with the PURPLE vMEME dominate culturally, mental illness still tends to attract real stigma. These young people viewed Schizophrenia with abhorrence; they don’t want to have anything to do with mental illness or anything that causes it. The kind of educational programmes Corry is proposing may well have a major impact with this kind of teenager.
(Incidentally, when asked what was a ‘safe’ level of cannabis use, I gave the Department of Health 2005 guideline of 50 joints (average cannabis content) per year. One student went white at this while his mates laughed at him, one of them saying, “Fuck me, you must do 50 a week!”)
Importantly Paul Corry and Rethink are against reclassification on the grounds that it will criminalise what they believe should be perceived as a health issue.
Simon Heffer, in an otherwise-heavy handed piece in the Daily Telegraph, made the point that reclassification would give the courts a wider and more stringent range of penalties, particularly for use with traffickers.
If we aimed to implement both Corry’s and Heffer’s proposals but also looked to address Corry’s concerns…
# Firstly, the DfES would implement programmes in both primary and secondary schools to educate children and teenagers about the dangers of cannabis (and other drugs). Children will pass some of this on to their parents. (Perhaps, given the likely cost to the National Health Service of more people developing psychoses, perhaps the Department of Health could fund anti-cannabis educational campaigns in the media…?)
Secondly, reclassification would encourage and enable the police and the courts to tackle the dealers and traffickers. If the general public are being made more aware of the dangers of cannabis use, then the police should receive more support in directing their resources this way.
Thirdly, as Rethink is campaigning for, the NHS should put much more resources into identifying and helping people with mental health problems. At the same time the Ministry of Justice can issue regulations directing police to treat personal use levels of possession either as a cautionary offence (as under the current ‘C’ classification) or to seek a conviction requiring medical treatment, if appropriate.
While I was never much of a cannabis user – never a smoker, so very uncomfortable with that method of ingestion! – I freely admit I have ‘dabbled’ at times in the past. (Since I’ve yet to develop any form of psychosis – at least I don’t think I’m psychotic!! – I can only thank God I don’t seem to have the genetic predisposition which makes cannabis a near surefire route to Schizophrenia.). Until recently I approved of the Independent on Sunday’s legalisation campaign. I whole-heartedly approved of Blunkett’s 2004 decision. Today I have friends who are users. I have no wish for my friends to be criminalised. On the other hand, we need to recognise cannabis for the highly dangerous drug it is, deglamourise it and deal very harshly with those who deal and traffick in it.
I’ve had to deal with Schizophrenics. Believe me, if we can prevent some people from developing the illness, it’s most definitely worth it.