There is an increased risk of serious violence and homicide during a patient's first episode of psychosis, according to UNSW-led research.
The study, which has been published in the Medical Journal of Australia, shows that 8.8 percent of a total of 1052 homicides in NSW between 1993 and 2002 were commited during a psychotic illness.
Of the 88 people charged with homicide and having the defence of mental illness, 54 of them (61 percent) committed the act during their first episode of psychosis.
The study now means it is possible to estimate the risk of lethal assault during different phases of mental illness.
"Of particular concern is the finding that 40 percent of the patients saw a doctor or mental health worker in the fortnight before the lethal assault," said Dr Olav Nielssen, the chief investigator of the research and a UNSW conjoint academic at St Vincent's Hospital. "Health professionals should be made aware of the increased risk of serious violence in the first episode of psychosis
"The first episode of psychotic illness should be considered as a psychiatric emergency. They should be considered to be at a greater risk of serious violence than those in subsequent episodes."
Conversely, the risk of homicide by patients with established illness is very low, estimated to be about one in 8,800 patients per annum. This would appear to indicate that the public can be reassured about the relative safety of patients with chronic mental health illness living in the community.
The victims of homicide in the study were mostly family members or close associates.
"This should lead to better understanding of the first episode of illness and in turn better treatment," said Dr Nielssen.
The full report is on the MJA website