I am often asked the question “if cannabis was as freely available as alcohol would more use it and would its harms increase?. Of course the answer is yes to both. However as about half of young people use cannabis, the increase from removing criminal sanctions would be relatively modest unless it was actively marketed as is alcohol. Certainly the Dutch coffee shop model of regulated but not legalised cannabis access appears not to have increased use since young people in the Netherlands have some of the lowest rates of cannabis use in Europe.
Perhaps the more interesting question is in this circumstance would be what would the net effect on population harms be? Would liberalising access to cannabis reduce alcohol use to an extent that might reduce the sum total of harms? This issue is touched on in my new paper in the Journal of Psychopharmacology [Weissenborn and Nutt 2011, Popular intoxicants: what lessons can be learned from the last 40 years of alcohol and cannabis regulation? (PMID:21926420)]. The key points of this paper are briefly outlined below.
A good measure of harm is the costs to the NHS. Hospital admissions for cannabis number less than 1000 per year whereas alcohol now accounts for 1000x as many – over a million last year of which 13,000 were aged under 18yrs. The role of cannabis in causation of schizophrenia is still controversial – the ACMD in their 3rd cannabis review estimated that to stop one case of schizophrenia one would have to stop 5000 young men or 7000 young women from ever smoking cannabis. Some studies are now suggesting cannabis may help patients with schizophrenia. In contrast, that alcohol causes liver disease is as incontrovertable as is its contribution to the massively accelerating death rates from liver disease in the UK. The frightening contribution that alcohol use makes to domestic violence, child abuse and road traffic accidents were some of the reasons why alcohol scored as the most harmful drug to UK society today in the ISCD scale of drug harms, published in the Lancet last year.
Until the last government induced them to think otherwise by making cannabis a target, the police have always taken the view that cannabis users were much less prone to violence than those intoxicated with alcohol. Indeed the police were strong supporters of the ACMD recommendation to downgrade cannabis to Class C in 2004. It seems likely that the recent rise in alcohol intake in the UK may have been in part due to the pressure of anti-cannabis policing leading to young people switching their preferred intoxicant to alcohol.
Estimating the true relative harms of alcohol and cannabis is not easy as there are no societies today where the two drugs are equally available. However where neither are legal – as in some Islamic states – alcohol appears to cause more dependence than cannabis, even in Morocco a traditional cannabis growing country.
Taken together we estimate that alcohol is at least twice as harmful to users than cannabis and 5 times more harmful to society. The obvious conclusion is that the current legislation criminalising cannabis users is illogical as well as inhumane and may be causing much more harm than it does good. Time for a rational intervention Mr Cameron?
The full paper can be found in the Journal of Psychopharmacology http://jop.sagepub.com/content/early/2011/09/03/0269881111414751