Victoria's beleaguered mental health system will face scrutiny from a coronial inquiry into the deadly rampage in Melbourne's CBD last week, amid claims the tragedy could have been avoided if Dimitrious Gargasoulas' apparent mental health issues had been treated earlier.

Several prominent psychiatrists have warned that inadequate funding combined with a surge in the number of young people presenting with drug-induced psychosis has placed enormous strain on the system, with many falling through the cracks.

"Acute mental health services in this state have been decimated and these types of things will happen more and more," said psychiatrist Dr Helen Schultz.

"This guy should have been treated way before it got to this. It's our duty as a society to get these people and help them before they become a risk to themselves or others," she said.

Dr Schultz said changes to Victoria's mental health laws had made it increasingly difficult to involuntarily commit those afflicted with serious mental health disorders, who are incapable of recognising their illnesses or providing consent for treatment.

"Someone like him (Mr Gargasoulas) will never present for help. He probably doesn't think he has a problem, he probably thinks the world has a problem. We need a more assertive model of care to help those who are unable to give consent, if we are to keep the community safe," she said.

Australia's most prominent mental health advocate Patrick McGorry said the state's mental health system was under siege following a 50 per cent increase in those seeking treatment without any significant funding increase.

Suicide is the leading cause of death for Australians aged between 15 and 44, with almost seven people taking their life every day. Professor McGorry warned there had also been an increase in the number of murders committed by sufferers of serious mental health disorders.

Professor McGorry said early intervention was crucial in treating young people with psychosis, but many were unable to find a bed in the public mental health system.

He said police should not be blamed for failing to identify Mr Gargasoulas' apparent mental health issues.

"It's the poor old police who have been left to carry the can. Even with the best training, they are not mental health experts or clinicians."

Last year, a review of Victoria's health system by Dr Stephen Duckett recommended significant investment in the state's mental health system, with more than 1.2 million Victorians requiring assistance.

Mental Health Minister Martin Foley responded to the report by announcing 130 new staff, along with plans to expand capacity for treatment of youth and high-security patients.

The Federal Government currently spends about $10 billion a year on mental health but Professor McGorry said about half of this was spent on welfare payments.

It is estimated that up to half of all Australians will suffer from mental illness at some point in their lives.

Despite the pervasiveness of mental illness, Professor McGorry said the issue had not resonated with politicians or the public until recently.

Donations for the immediate families of those killed can be made via the website www.vic.gov.au/bourkestreet.html.

For urgent support, call Lifeline on 13 11 14. Witnesses and victims requiring support can also call the Victims' Support Helpline on 1800 819 817.

A vigil is being planned from 5.30pm on Monday at Federation Square.