Marijuana In The UK And The Advisory Council On The Misuse Of Drugs

“There are few substances which are surrounded by more controversy, and which have at the same time such important and potentially far-reaching public health implications”, the late Professor Henry wrote.
The ACMD, the body tasked to adjudicate the evidence on cannabis, never shared this view and as a result fell foul of the debate. It has taken the sacking of Professor Nutt, the brouhaha and the publicity surrounding it, to pull attention back to the science on cannabis effects; science that he and the ACMD were so slow to assess, so little interested in and so quick to dismiss.
Last week the BBC’s The Report programme asked the question of why on earth the ACMD recommended cannabis’ downgrading in the first place. Labour MP Gwyn Prosser explained. For those arguing in favour, in the pro-liberalism political climate of David Blunket’s accession to the Home Office, “it was all but a done deal, they were pushing at an open door ….” The ACMD was party to that process.
Its first cannabis report (the only one that the ACMD Chair ‘had pleasure in enclosing’ to the Home Secretary), which recommended reclassification to C, was just 22 pages long. As a review of the classification of cannabis preparations, ‘in light of the current scientific evidence’, it was nominal and cursory. It drew not at all on the “large scientific literature on the effects of cannabis on human health and human society” available at the time. Its recommendation was based on drugs use prevalence statistics, speculations about and reports on decriminalisation regimes. Of the 24 references listed, only 4 referred to the scientific literature on effects. Yet when Mary Brett, a biologist and former grammar school head of health education, surveyed it for herself, she found no less than 44 pre 2002 scientific publications on the negative impact of cannabis; evidence of psychosis in cannabis users dating back to 1972. The review skated over the evidence and paid lip service to cannabis harms alone.
Professor Robin Murray’s new research on the causal link between cannabis and schizophrenia was published eight months afterwards. In 2005 Charles Clarke not unreasonably requested the ACMD to examine all the evidence relating to mental health; he directed them to the changed content of cannabis; forensic lab data was already showing that consumption had shifted from imported resin to home grown herb with a much higher THC content and a dangerously altered THC/CBD ratio – ’skunk’ which had become a rite of passage for ever younger teenagers.
The ACMD were quick to express their misgivings. Politicians were ‘pandering to the media’ said Lord Adebowale, a non-scientist ACMD member. He was not convinced there was fresh evidence. Sir Michael Rawlins (then Chairman) also seemed to have closed his mind. At a conference in the April of that year he confirmed he would not be ‘confused’ by the new data. True to his word only 5 pages of the 36 page response dealt with the massive output on the effects of cannabis on mental health, described as a ‘biologically fraught hypothesis’. Cannabis could lead to short lived panic attacks and worsen the symptoms of schizophrenia, it conceded. It could ameliorate them too. It was not a necessary, nor a sufficient, cause for the development of schizophrenia. The evidence for consumption of more potent cannabis was lacking. That was the medicine doled out to the Home Secretary. He took it.
So when Jacqui Smith asked them to look at the evidence again the ACMD were visibly affronted. Sir Michael Rawlins made his discontent public, the 10 minutes slot for cannabis on the agenda collapsed to two. He devoted them to grumbling – saying that he wished they had not been asked. One (non scientific) Council member said afterwards he had no intention of ploughing through the evidence again.
In the meantime the ACMD’s deputy chair had already queered the pitch for a dispassionate review. In full media glare Professor David Nutt had published an article in the Lancet in which he set out to demonstrate, through delphically derived but incomplete polling, a new classification of harms in which alcohol and tobacco emerged more harmful than cannabis and ecstasy. His intention was clear – to invalidate the distinction between licit and illicit substances.
What he ignored (or perhaps pandered to) was the fact that while the excess mortality and healthcare costs associated with the use of tobacco and alcohol are well known, those for cannabis remain largely unknown. He took the lack of comparable definitive evidence on cannabis concerning the population as a lack of evidence of its harm for either individuals or society.
At 56 pages long, the ACMD’s final report referred to more scientific papers than before. But if a precautionary principle was applied it was to the data itself, not to its implications or to their classification recommendation. So cautious were they that they completely ignored the key published British longitudinal data on cannabis use and schizophrenia. They relied instead on a GP data base survey they decided to commission from one of their own members
The analysis they so bizarrely ‘ostracized’ was of a South East London longitudinal cohort covering the period between 1966 and 99 which uniquely allowed for the examination of trends in cannabis use prior to first presentation with schizophrenia. It demonstrated a continuous and statistically significant rise in the incidence of schizophrenia between 1965 and 1997, one which had doubled over the last 3 decades, with the greatest increase in people under 35. It suggested that up to 20% of schizophrenia cases could be cannabis attributable.
The ACMD’s decision to rely exclusively on a survey of its own commissioning which did not specifically look at cannabis use was curious. Presented by one of its own members, Professor Ilana Crome, as unpublished evidence, she reported the annual incidence of diagnosed schizophrenia and psychoses had fallen between 1996 and 2005. Professor Murray dismissed this as invalid: “I have known about this study since its inception and advised the authors that they were unlikely to be able to come up with meaningful results. Firstly, a major problem concerns the diagnoses. In my experience GP diagnoses of psychiatric disorders are not very accurate. Secondly, we do not know how many cases of psychosis are dealt with exclusively by psychiatrists and GPs don’t know.”
His contention is that there is no significant or well done study that has not shown early onset of cannabis use to be associated with psychosis. Since 2002 he points to no less than eight cohort studies all of which show the risk of psychosis to be higher in those that smoke cannabis – a risk that increases by 6 to 7 times for heavy smokers, risks that for adolescents are disturbingly high and that show early users run into greatest problems. Starting by 15 the risk is 4 times higher than starting at 18 – a data trend which suggests the risk multiplies for each year younger.
Yet the ACMD remained adamant that these studies did not meet their bar of ‘proof beyond reasonable doubt’ and that more research was required. Others scientists begged to differ saying the persistent association was robust to methodological challenges.
Whether recently published findings which confirm that THC induces a transient, acute psychotic reaction in psychiatrically well individuals would have persuaded them, is anyone’s guess. Meanwhile the ‘Cannabis Dependency Units’ as psychiatrists describe their first contact schizophrenia wards, continue to take their toll. And while Holland finds its three dedicated residential rehabs for their severest adolescent (13 – 20) cannabis dependents to be insufficient and is building more, to create 600 places, we, in the UK, have none. We leave our stoned and de-motivated youngsters on the streets. For that we can thank the ACMD’s lassitude.
Source: by Kathy Gyngell, UK Centre for Policy Studies 29th November 2009

Filed under: Social Affairs :

Back to top of page

Powered by WordPress