© Angela WyliePatrick McGorry ... a formal complaint was lodged
The former Australian of the year Patrick McGorry has aborted a controversial trial of anti-psychotic drugs on children as young as 15 who are ''at risk'' of psychosis, amid complaints the study was unethical.

The Sun-Herald can reveal 13 international health experts lodged a formal complaint calling for the trial not to go ahead.

They were concerned children who had not yet been diagnosed with a psychotic illness would be unnecessarily given drugs with potentially dangerous side effects.

Quetiapine, sold as Seroquel, has been linked to weight gain and its manufacturer AstraZeneca, which was to fund the trial, last month paid US$647 million ($622 million) to settle a lawsuit in the US, alleging there was insufficient warning the drug may cause diabetes.

Professor McGorry, one of the Prime Minister's key mental health advisers, planned the trial at Orygen Youth Health in Melbourne, listing it on the Australian New Zealand Clinical Trials Registry last March.

It was to investigate whether the drug would decrease or delay the risk of people aged between 15 and 40 with early signs of mental illness, developing a psychotic disorder such as schizophrenia.

Last month, psychiatrists, psychologists and researchers from Australia, New Zealand, Canada, Britain and the US lodged a complaint with the ethics committee of Melbourne Health, the umbrella service which includes Orygen. They argued there was little evidence the onset of psychosis can be prevented and it was potentially dangerous to use anti-psychotics on those who merely had risk factors such as a family history or deterioration in mental health, with evidence showing up to 80 per cent will never develop a disorder.

Professor McGorry insists the decision to scrap the trial was made in June and is unrelated to the complaint, which he said he was only alerted to just over a week ago.

He said Orygen had to choose between the drug trial or pursuing another trial using fish oil - which had proven useful as an early intervention treatment for schizophrenia in a smaller study. It opted for fish oil because it had less potential for side effects.

Melbourne Health's research ethics committee will still consider the complaint in September.

The Sun-Herald recently revealed a growing backlash against the government's mental health reforms, with Professor McGorry's peers claiming his youth early intervention model had been ''massively oversold''.

Associate Professor Geoff Stuart from La Trobe University's school of psychological sciences, who signed the complaint, said serious questions about the aborted trial remain.

''He [Professor McGorry] was willing to endorse a trial which was exploring the use of anti-psychotic medication in an at-risk group,'' he said. ''There's a major ethical issue about medicating four people to supposedly save the fifth when you're not saving them anyway, you're just masking their symptoms.

''We're talking about kids as young as 15 who could get a full dose of anti-psychotics and they're not psychotic.''

Anti-psychotics are vital but should not be used without clear evidence of the benefits, experts say.

Professor McGorry admitted the evidence suggested anti-psychotics were not effective as a first-line treatment for the at-risk group. But he said the risks had been exaggerated and he would consider a similar trial on patients for whom other treatments had failed.