Cannabis and mental health – to B or not to B (again)

Welcome to a new feature on UKCIA as we enter the world of blogs – the UKCIA newsblog

The debate over whether cannabis should be re-reclassified back to class B is one of those issues deeply interesting to politicians, but about which most cannabis users really couldn’t care less. However, the British government has dug a deep hole for themselves over it.

When Mr Brown was appointed last year, he immediately announced yet another review of the classification of cannabis. He then went on to say he wanted to reclassify anyway, no matter what advice he had from the experts, something he repeated again this week. The “experts” are, of course, not just any old experts, they are experts appointed by the government, so ignoring them is hard to explain with any logic.

The body charged with doing the review – the ACMD – has apparently recommended there be no change. So Mr Brown is now in a difficult position of his own making, either he accepts the advice of his own experts, or chooses to ignore that advice which would be the first time such advice has been ignored. If he does this, it would prove beyond all doubt that UK drugs policy is not evidence based.

The real bombshell however concerns the claims that cannabis – particularly the “new” strains which are claimed to be so much stronger than cannabis of old – have lead to an increase in mental illness, in particular schizophrenia. UKCIA has been following this debate over the past few years with interest. However, research at Keele University is reported to show a decrease in the rates of such illness over the past 10 years. If true, this blows the ‘cannabis causes mental illness’ argument out of the water. The research has been done for the Home Office and when asked Keele university refused to comment on it, saying only that it was “confidential”.

As this research from Keele has been leaked to the media it should now be published and the full results made public, but don’t expect Gordon to do that any time soon.

There are many reasons to have expected a rise in severe mental illness anyway, never mind any effect cannabis might have had. Increased use of other drugs such as speed and cocaine, increases in family breakdowns, the stress of urban living and soldiers returning home from wars would all be added risk factors. However, demonstrating a rise in the rates of severe mental illness is central to the debate as to whether cannabis is indeed a causal factor. If the reports of this research are true and there has actually been a fall in rates of illness, the debate is, frankly, over.

So what of the claims that cannabis makes mental illness worse and delays recovery? Of course that is still probably true and the advice that children need to be protected from the cannabis trade is still good advice. Returning cannabis to class B would do nothing to solve that of course.

Guardian article Friday 4th April 2008
“The Guardian understands that at the ACMD meeting, the 23 medical and drug experts heard a personal presentation on the possible mental health impacts of higher potency cannabis from psychologist Dr Martin Frisher, of Keele University pharmacy school. The presentation used unpublished data from a confidential report he has drawn up for the Home Office.

He and his colleague Professor Illana Crome, of Keele’s academic psychiatry unit, used data from 183 GP practices across Britain between 1996 and 2005 to work out whether schizophrenia is on the rise, and whether it can be linked to the increase in cannabis use since the 1970s.

Their confidential paper found that between 1996 and 2005 there had been significant reductions in the incidence and prevalence of schizophrenia. From 2000 onwards there were also significant reductions in the prevalence of psychoses.”

Times article Friday 4th April 2008:
“The council’s decision came after a discussion of research from Keele University on trends in schizophrenia. The study found nothing to support a theory that rising cannabis use over the past three decades had led to increases in the incidence of schizophrenia in later years. Instead, the research by Martin Frisher, of the school of pharmacy, and Ilana Crone, of the academic psychiatry unit, said that between 1996 and 2005 there were significant reductions in the prevalence of schizophrenia and from 2000 onwards in the prevalence of psychoses.

“The data are not consistent with the hypothesis that increasing cannabis use in earlier decades is associated with increasing schizophrenia or psychoses from the mid1990s onwards,” the report said.”



UKCIA is a cannabis law reform site dedicated to ending the prohibition of cannabis. As an illegal drug, cannabis is not a controlled substance - it varies greatly in strength and purity, it's sold by unaccountable people from unknown venues with no over sight by the authorities. There is no recourse to the law for users and the most vulnerable are therefore placed at the greatest risk. There can be no measures such as age limits on sales and no way to properly monitor or study the trade, let alone introduce proper regulation. Cannabis must be legalised, as an illegal substance it is very dangerous to the users and society at large.