May, 2002

A report out of Australia suggests that amphetamines and cannabis use is contributing significantly in causing schizophrenia in young people.

Psychiatrist Maryanne O'Donnell directs the mental health outpatients unit of the Prince of Wales Hospital Kiloh Centre in Sydney.

In a recent interview Dr O'Donnell said there was evidence that at least 50 per cent of people with psychotic illnesses used substances.

She said based on both her own clinical experience and wider anecdotal evidence, the use of drugs was causing young people to have more severe schizophrenic episodes or bringing episodes on at an earlier stage of their lives.

"The real concern for us at the moment is that ... the prevalence of substance abuse by young people is actually making the way in which the illness presents and the type of symptoms that people present with much more serious," she told AAP.

"We often have people presenting in a very much more disturbed way because of the fact that they are using substances in association with the psychotic symptoms that they are experiencing."

The worst drugs were psychostimulants such as amphetamines and the most common culprit was cannabis, she said.

"Where there is repeated and frequent use from a very early age we have real concerns that that is exacerbating the illness and bringing it on earlier," Dr O'Donnell said.

"Certainly (there has been) an increase in the severity of the presentations that we are seeing."
Dr O'Donnell said current research indicated that some people are born with a vulnerability to developing schizophrenia. The illness may then develop in later life as a reaction to certain life experiences.

The onset of schizophrenia usually occurred between 15 and 25. "We think it's a neurodevelopmental illness," she said.

"As the brain is maturing, as the individual is maturing ... with all the stresses of adolescence, it's in that final maturing of the brain before adulthood that this illness manifests itself.

"What happens through their lives makes a difference whether the predisposition manifests itself as the full blown illness."