Study: Extra-Potent Weed Linked to Psychotic Mental Conditions

As reported in The Times (London): Quarter of psychotic cases linked to skunk cannabis.

    Smoking extra-strong varieties of cannabis could be the cause of a quarter of  all new cases of psychotic mental conditions such as schizophrenia, a  six-year study concludes.

    Researchers found that about 60,000 people in Britain suffered hallucinations  and paranoid episodes brought on by the use of high-potency skunk. Daily  users of skunk were five times as likely to suffer psychosis as those who  never used it.

    The findings prompted claims that smoking cannabis was like playing “Russian  roulette with your mental health”. Psychiatrists said that there was now an  “urgent need” to educate the public about the risks.

    The report comes amid warnings that even newer varieties, some of them more  than twice as potent as those available on British streets, have been  developed in the Netherlands.

    The study, by researchers from the Institute of Psychiatry, Psychology &  Neuroscience at King’s College London, is due to be published in The Lancet Psychiatry journal this week.

    The research looked at almost 800 working-age adults from one area of south  London, half of whom had recently been treated for a psychotic episode for  the first time. Incidence of schizophrenia in the area has doubled since the  mid-1960s, a trend thought to be linked to drug use.

    Cannabis use in the UK overall has fallen by about 40 per cent in the past  decade, but the drug’s potency has increased sharply in that time. Levels of  tetrahydrocannabinol, the main psychoactive compound, are about 15 per cent  in skunk, compared with about 4 per cent in traditional “hash” cannabis.

    The study noted: “Compared with those who never used cannabis, individuals who  mostly used skunk-like cannabis were nearly twice as likely to be diagnosed  with a psychotic disorder if they used it less than once per week, almost  three times as likely if they used it at weekends, and more than five times  as likely if they were daily users.”

    It found that skunk use was the “strongest predictor” of psychotic illness in  those studied and that 24 per cent of new cases in the area could be  attributed to it.

    The study said: “The worldwide trend of liberalisation of the legal  constraints on the use of cannabis further emphasises the urgent need to  develop public education to inform young people about the risks of  high-potency cannabis.”

    Mark Winstanley, chief executive of the charity Rethink Mental Illness, said:  “Essentially, smoking cannabis is like playing a very real game of Russian  roulette with your mental health.”