And So Has Potency

I have never taken any illegal drug, yet I still have all and sundry wrong with me. Hey ho, having supported William Hague for Leader, under that Leadership the Daily Telegraph supported the legalisation of cannabis, along with same-sex marriage and a fully elected second chamber, all three of which were fiercely ruled out by the Labour Government of the day. But now, Sarah Knapton writes:

Cannabis users are twice as likely to carry out violent acts, a review by King’s College London has found. An analysis of 63 studies, involving more than 265,000 people, found a strong link between violence and cannabis, with users both more likely to physically harm others and suffer abuse themselves. The research showed that cannabis users were also three to four times more likely to have committed violence that led to a criminal conviction compared with non-users.

Experts said the Government should be aware of the drug’s links to violence in light of ongoing pressure to legalise cannabis, including support from Lord Khan, the Mayor of London, and Zack Polanski, the Green Party leader. Although the review cannot prove that cannabis is the definite cause of the increased violence, experts from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) said the drug may induce paranoia, which could lead to feelings of anxiety and threat.

Prof Sir Robin Murray, of the IoPPN at King’s, said: “If cannabis does play a causal role, the most likely mechanism is that, as we know, heavy use of cannabis is associated with paranoia. Users are therefore more likely to misinterpret the actions or speech of others and conclude that they have bad intentions towards them. They may then attack people, believing they are protecting themselves. As cannabis becomes more commercialised and legalised around the world, the conversation about its risks has focused mostly on the person using it. This review shows that violence, both committing it and experiencing it, needs to be part of that conversation too.”

Lord Khan, Mr Polanski and Ed Davey, the leader of the Liberal Democrats, have all backed the decriminalisation of cannabis for personal use. Countries including Canada, Austria, Italy, Belgium, Brazil, Chile, Estonia, Germany, Israel, South Africa, Switzerland, Malta, have all legalised, or decriminalised, cannabis for personal use, as well as 31 states of the United States. Many believe legalisation disrupts the criminal market, allows the drug to be taxed and encourages greater regulation and safety, while freeing up the police. However, opponents warn that there is little evidence that making cannabis legal stops black market suppliers and argue it tends to lead to stronger drugs, which can trigger mental health issues, including psychosis and schizophrenia.

Legalisation ‘makes drug stronger’

In parts of the US where cannabis has been legalised, it is now possible to obtain the drug with more than 80 per cent tetrahydrocannabinol (THC) – the active ingredient. In the UK, average street cannabis has about 16 per cent. “My personal view is that wherever cannabis has been legalised in the Western world, use has increased, and so has potency,” added Sir Robin. The new research showed that people who used cannabis were also around one and a half times as likely to be victims of violence. The link was stronger for women than for men. The team’s definition of violence included physical, sexual and psychological violence towards another person, both within relationships and outside them.

For those in psychiatric care, cannabis users were around two and a half times as likely to be violent as other psychiatric patients who did not use cannabis. Dr Marta Di Forti, co-author of the study, said: “As a clinician, I’ve seen how heavy cannabis use can be a factor in violence. We’ve been cautious for a long time about how far we could go in describing this link, but a review of this size lets us speak with more confidence about the risks, while being careful not to stigmatise people who use cannabis more broadly.” 

Britain allows the legal use of cannabis on medical prescription for certain conditions. Some experts warned that the link between cannabis and violence may be caused by the environment that users often lived in, rather than the drug itself. Prof Simon Moore, director of the violence research group at Cardiff University, said: “The review cannot say whether cannabis itself or the environments in which it is used explain the violence. Because cannabis remains illegal in most jurisdictions, and illegal markets bring users into contact with people and places where violence is more likely, this omission is notable.” The research was published in the journal Psychological Medicine.