Eight out of ten people who suffer the onset of serious mental illness are heavy cannabis users, claims a scathing report on the effects of the drug. The report found that the huge majority of those undergoing a first episode of psychiatric disorder, schizophrenia or similar mental breakdowns are habitual users of the drug. The overwhelming evidence of a connection between cannabis and schizophrenia was confirmed in a report delivered to Tory chiefs as part of leader David Cameron's review of party policies. It listed no fewer than 400 different scientific studies that point to links between use of cannabis, illness and destructive behaviour. The findings will pile pressure on Mr Cameron to tie his party to a pledge to reclassify cannabis as a seriously dangerous drug. The report was prepared for the Tories' social justice policy review in the wake of growing criticism of the Government's decision to downgrade the criminal seriousness of cannabis from Class B to Class C in 2004.This means that police officers no longer regularly arrest adults found with the drug, and critics say it has encouraged young people to believe that cannabis is no longer officially regarded as dangerous. But the new study said that the risks 'demand that cannabis now receives the level of health attention that has been devoted to Britain's other two most favourite drugs, tobacco and alcohol.' Among authorities cited by the report is Professor Peter Jones of Cambridge University, who found that 80 per cent of first episode pyschiatric disorders occurred in those who were heavy users of cannabis. It quoted Professor Jones: 'Cannabis is a huge issue for psychiatric services at the moment. I work in a first-contact schizophrenia service and it might as well be a cannabis dependency unit.' Professor Jones estimated that children who start smoking cannabis at the ages of 10 or 11 may have treble the risk of developing schizophrenia of other children. He added: 'I think this is an iceberg effect. If you were able to measure the toll on GCSE results, A level results, training and social development, we were have a much bigger number of deleterious effects.' Professor Robin Murray of the Institute of Psychiatry told the inquiry: 'Five years ago, 95 per cent of psychiatrists whould have said that cannabis does not cause psychosis. Now, I would estimate that 95 per cent say it does. It is a quiet epidemic.' The report said that 1.75 million people are thought to use cannabis in Britain each month, that more than a quarter of 14- and 15-year-olds have used it, and that it ranks behind only alcohol and tobacco as the country's most popular drug. It listed research which identified links between cannabis and damage to the cardiovascular system; cannabis and damage to the immune system; and smoking cannabis and cancer. The report also explored scientific literature linking cannabis to depression and aggression; to driving risks; to impaired educational performance and ability to reason; and the likelihood that heavy users will become dependent on the drug. It pointed to the 'gateway effect' under which users of the most harmful and addictive drugs like heroin began their illegal drug habits smoking cannabis. Using cannabis is also associated with problems for pregnant women including lower birth weights and increased likelihood of premature birth, the report said. Mary Brett, the researcher who prepared the study, said she was angered to hear Tony Blair's remark last year that downgrading cannabis was justifiable because 'it was worth seeing what happened.' She said: 'Was this just some huge experiment conducted primarily on our vulnerable young people? How many of them would, prior to down-classification, ever have been tempted to try the drug? And how many now find themselves with a psychiatric problem, perhaps for life?'
