Psychosis and Marijuana - Study in Australia

BRISBANE, Australia, May 8, 1997 - A psychiatrist today cautioned against decriminalising cannabis following a study showing its use may hamper recovery in young people suffering early psychosis. Dr Tim Rolfe, of Dandenong Hospital, said he had observed high levels of cannabis use among young people treated for a first episode of schizophrenia-like illness. A study of 60 young adults researched at the Centre for Young People's Mental Health in Parkville, Victoria, found 30 per cent used cannabis at least daily and a further 35 per cent at least weekly. Dr Rolfe told the Royal Australian and New Zealand College of Psychiatrists' 32nd annual congress in Sydney that the figures were higher than those for the average population and greater than previously reported for people with a mental illness.

He could not say whether they indicated cannabis may precipitate psychosis, or whether people with psychiatric conditions were more likely to turn to cannabis. "In this study I looked at whether cannabis use affects the nature of the presentation and symptoms and so far I have seen a greater level of depression in people who are cannabis users," Dr Rolfe told AAP. The young people, aged 16 to 30 years, were assessed again after two months of pharmacological treatment. "The trend is for those people who were previously cannabis users and then gave up to recover to a greater extent," Dr Rolfe said. Improvement was measured using standard psychiatric assessments of attention-span and ability to experience pleasure. Dr Rolfe said after minor intervention for their psychosis, half of the cannabis users gave up, many citing their own suspicions "it might be harmful". Dr Rolfe said the study was important in view of the ongoing debate in Australia on decriminalising cannabis. "I would be guarded about it (decriminalisation) in view of these results," he said. Dr Rolfe said wider availability may be associated with poorer outcomes in the long term. However benefits could include the fact that young people would not hide their use from doctors, and, if it was less expensive, may direct their funds to more useful ends, "such as housing".