Smoking just one cannabis joint raises danger of mental illness by 40%

Daily Mail 26 July 2007
A single joint of cannabis raises the risk of schizophrenia by more than 40 per cent, a disturbing study warns. The Government-commissioned report has also found that taking the drug regularly more than doubles the risk of serious mental illness. Overall, cannabis could be to blame for one in seven cases of schizophrenia and other life-shattering mental illness, the Lancet reports. The analysis does not look at the age at which schizophrenia is likely to develop. However, previous studies have shown that smoking the drug as a teenager raises the risk of developing schizophrenia in one’s twenties or thirties.The researchers, from four British universities, analysed the results of 35 studies into cannabis use from around the world. This suggested that trying cannabis only once was enough to raise the risk of schizophrenia by 41 per cent. At greatest risk, however, were heavy users, with those who took cannabis over 100 times having more than double the risk of those who never touched the drug. With up to 40 per cent of teenagers and young adults in the UK believed to have tried cannabis, the researchers estimate that the drug could be behind 14 per cent of cases of schizophrenia and other psychotic illnesses.

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