Schizophrenia boosts crime likelihood

By MARTIN JOHNSTON health reporter

People with schizophrenia are three to five times more likely to commit crimes than those without the mental illness, the largest study yet of the link has found.

Australian researcher Professor Paul Mullen told a psychiatrists' conference in Christchurch that his study compared records of about 2800 people with schizophrenia to a similar number without it over a span of 25 years.

It found that convictions rose at the same rate in both groups, discounting the theory that moving most of the mentally ill out of institutions has led to more crime by them - a conclusion already established by New Zealand research.

But the Australian study also found that 8.2 per cent of the schizophrenic group had been convicted of a violent offence - a rate 4.5 times the 1.8 per cent of the other group.

The research director at the Mason Clinic in Auckland, Dr Sandy Simpson, found New Zealand's rate of homicide by the severely mentally ill was similar to the Australian study's.

But while the proportion of violent crime by schizophrenics was static over time in the Australian study, the percentage of homicides by the mentally unwell in New Zealand declined.

Dr Simpson said both studies showed that violence by people with severe mental illnesses was an issue. "As a contribution to total societal risk, people with schizophrenia, although slightly higher risk, do not present a major or overwhelming risk. Less than 0.2 per cent of the people with schizophrenia committed homicide over a 13-year period."

Mental Health Commission chairwoman Jan Dowland said most people with mental illness were no more likely to commit a violent crime than anyone else. Young men posed a greater risk of being violent. Professor Mullen said most schizophrenics committing crimes had drug and alcohol problems, which were a relevant factor but not the whole answer.

"Other research in Scandinavia recently has strongly suggested that it's to do with personality problems which are found particularly in those with schizophrenia.

"The other thing our research suggests is important is the social conditions under which many people disabled by schizophrenia live; they live in disadvantaged situations."

They were more likely than others to be unemployed, to live in high-crime neighbourhoods and in inadequate housing.

He urged addressing these problems for schizophrenics, offering therapy for personality difficulties such as insensitivity to others, helping them into jobs or at least providing structured activities and support. "If you do these things you could probably reduce crime by 5 to 10 per cent."

Dr Simpson agreed and said NZ's mental health services needed to expand to match this standard.

"Quite a lot of emphasis on service development does need to go on safe and secure housing and employment opportunities," he said, "as well as the standard treatment and access to drug and alcohol assessment and psycho-social treatment."


Crime rates

* People with schizophrenia are 4.5 times more likely to have been convicted of a violent crime than those without the illness.

* Those with the illness are an estimated 0.7 per cent of the population.

* They commit 7 per cent of homicides in Australia.

* People with severe mental illness commit 7.7 per cent of homicides in New Zealand, a smaller proportion than 30 years ago.