BMJ 2019; 364 doi: https://doi.org/10.1136/bmj.l417 (Published 25 January 2019)Cite this as: BMJ 2019;364:l417
A debate on whether criminalising people who use cannabis protects against mental ill health did not take place because no one agreed to argue that current UK law protects the health of people who take the drug.
Instead, only David Nutt, professor of neuropsychopharmacology at Imperial College London, spoke on 23 January at the Royal College of Psychiatrists in London.
The motion to have been debated was: “Decriminalising cannabis use will lead to higher rates of mental illness.”
Wendy Burn, the college’s president, told The BMJ, “The concern, for psychiatrists, is the link between cannabis and mental illness. Later this year, the college will be thoroughly reviewing the evidence on the effects of cannabis use on mental health.”
Nutt, opposing the motion, told the audience that despite a 20-fold increase in cannabis use over the past 50 years, prevalence and incidence of schizophrenia and psychoses had not increased anywhere near in step.
He was highly critical of UK governments and the judiciary, alleging that they had often favoured policies of prohibition only for political reasons and that it was “indefensible” that patients were being punished for taking cannabis.
Such policies, he said, were responsible for increased recreational use of stronger and more harmful drugs, such as spice, methamphetamine, and crack cocaine.
“The British government has been lying about cannabis,” he said. “We’ve done exactly the wrong thing. Everything the government has done has confounded the problem.”
He said that prohibition impedes research into cannabis as a medicine. There is evidence that the plant can help in several indications including in psychiatry, he said.
The law is disproportionately used to punish non-white people, he said, and has created an underclass of people with criminal records.
During questions after Nutt’s talk, the audience, almost all psychiatrists, seemed not to object to much of what Nutt had said, at least out loud, although some wanted sources for his data and questioned his numbers.
On Twitter, some psychiatrists expressed concerns that cannabis can precipitate and worsen psychoses. “What about those folks who are teetering on the edge of psychosis and cannabis pushes them over? In clinic—EIS [early intervention service] especially—[it] often feels like a narrative of genetics→ stressors–> cannabis–> positive symptoms,” tweeted Rebecca McKnight (@Mcknight_DrR).
Nutt chaired the UK government’s independent advisers, the Advisory Council on the Misuse of Drugs, until he was sacked in 2009 for criticising UK legal drug classification as not reflecting the evidence on relative harms of different substances.1
The council recommended decriminalising personal possession of all illicit drugs in 2011, which the government immediately rejected.
Possession of cannabis, class B under the Misuse of Drugs Act, can be punished by up to five years in prison and an unlimited fine, although penalties often are not applied.2
Many international health authorities, such as the World Health Organization and UNAIDS, say that drug taking should be considered a health rather than a criminal justice matter.
They say that criminalising non-violent drug taking stigmatises people with drug use disorders and drives people who need help away from health and education services while obstructing evidence based activities that can reduce harm.
In April 2018 the Royal College of Physicians called for the decriminalisation of all use of currently illegal drugs such as cannabis, cocaine, and heroin3 in line with the Faculty of Public Health and the Royal Society for Public Health. The BMA has also called for decriminalisation of illicit drug use.
The BMJ has called for drug use to be decriminalised and for legally regulated drug supply markets.4
