Cannabis violence claims are \u2018misinformed and reckless.\u2019 A new book from US journalist Alex Berenson claims that increasing\u00a0cannabis use is causing violence in America.<\/p>\n
In the publication; Tell Your Children: The Truth About Marijuana, Mental Illness and Violence he goes on to say that a \u2018rise in cannabis induced violence will worsen\u2019 as global consumption grows.<\/p>\n
Closer to home, claims have been made in the Sunday Times newspaper that cannabis use is linked to some of Scotland\u2019s most notorious teenage killers in the wake of the conviction of a 16-year-old boy for the murder of Alesha MacPhail on the island of Bute, last year.<\/p>\n
Aaron Campbell told police he was \u2018really stoned\u2019 after being found guilty of creeping into the six-year-old\u2019s family home, taking her from her bed, raping and suffocating Alesha and leaving her with 117 injuries.<\/p>\n
In February this year the paper highlighted a further two teenage Scottish murderers in which cannabis use was said to play a role, as well as similar crimes elsewhere in the UK. However two prominent US scientists have described these claims as \u2018misinformed and reckless\u2019. Carl Hart is the chairman and Ziff professor of psychology and psychiatry at Columbia University and Charles Ksir is professor emeritus of psychology and Neuroscience at the University of Wyoming.<\/p>\n
Writing in The Guardian they say the evidence from their research is that \u2018aggression and violence are highly unlikely outcomes of marijuana use\u2019.<\/p>\n
\u201cBased on our own laboratory research, during which we have given thousands of doses of marijuana to people \u2013 carefully studying their brain, behavioural, cognitive and social responses \u2013 we have never seen a research participant become violent or aggressive while under the influence of the drug, as Berenson alleges.\u201d So, are the Cannabis violence claims are \u2018misinformed and reckless”<\/p>\n
They also compare Mr Berenson\u2019s book to a re-run of the US \u2018Reefer Madness\u2019 rhetoric in the 1930s. This narrative prompted by Drugs Czar Harry Anslinger – that cannabis use prompts violence – was partially responsible for the global outlawing of a drug which have previously been viewed as beneficial, and, at worst benign.<\/p>\n
Consultant Psychiatrist Prof Adam Winstock, the founder of the annual Global Drug Survey – in which 60,000 cannabis users detail their habits and use – does have concerns on the impact of early, onset cannabis usage.<\/p>\n
He says: \u201cAs someone who has worked with people who use cannabis for over 20 years my experience is that the relationship between cannabis and psychosis is limited to vulnerable groups, and those people who use it early in life.<\/p>\n
\u201cThe idea that cannabis use is not generally helpful in young people should not really be challenged. Most people agree that this is the time you have optimal brain and emotional development, and when you\u2019re developing it\u2019s best not to be chucking loads of chemicals in; whether it\u2019s alcohol, or weed, or anything else.\u201d<\/p>\n
Prof Winstock, of University College London, says today\u2019s street cannabis is much more potent than it has been in the past.<\/p>\n
Most research shows that cannabis with a high THC (Tetrahydrocannabinol – the cannabinoid which gets people \u2018high\u2019) content tends to have more psychoactive side-effects. Commonly coming with a 15% or greater THC content \u2018recreational\u2019 cannabis resin is over three times stronger than the strains available 20 years ago.<\/p>\n
Prof Winstock says: \u201cThis is now an issue because it so difficult to get anything else. For people, who don\u2019t want a high potency strain it\u2019s now almost impossible.\u201d<\/p>\n
Canada was one of the first countries to legalise medical cannabis usage and initially it was was not prescribed to anyone under 25, and while most states now have an age limit of 18, or 19 there is talk of raising the limit to 21 in some jurisdictions.<\/p>\n
But Prof Winstock is sceptical of the widely held view that cannabis causes depression: \u201cEarly onset cannabis use is more a marker of things going wrong in your life and those people have an elevated risk of depression. Heavy use leads to complications in home lives and relationships.\u201d<\/p>\n
As a supporter of the recent changes to UK legislation Prof Winstock added: \u201cI don\u2019t think the medical use of cannabis will complicate this issue. A regulated market will be able to address potency and change issues, and delay the onset of early cannabis use.\u201d<\/p>\n
The All Party Parliamentary Group (APPG) for Drug Policy Reform\u2019s official report, concludes that most literature supports a causal hypothesis between cannabis use and psychosis, particularly if usage starts at an early age and if the individual has a genetic predisposition to psychosis.<\/p>\n
But the report says \u2018it is unlikely that any one environmental factor – such as cannabis use – or any one gene can cause schizophrenia on its own\u2019.The author of this report, neurologist Prof Mike Barnes, dismissed links between cannabis use and violence as \u2018deluded wishful thinking\u2019 by its \u2018ill-informed opponents\u2019.<\/p>\n
He says: \u201cThe majority of good quality studies do confirm that there is a link between cannabis use and onset of schizophrenia or psychotic symptoms. The overall evidence suggests that cannabis can make symptoms worse in individuals already suffering from psychosis. \u201cAlso, it is likely that cannabis use in young people reduces the age of onset of psychosis.<\/p>\n