This year, 4 million Australians will experience mental ill-health. In our lifetimes, as many as half of us will encounter it. There are more people in Australia today with depression than there are suffering a common cold. And even more - one in seven Australians - will have an anxiety disorder this year.

The cost to the economy is estimated at $30 billion a year. This includes care and treatment and welfare payments, as well as countless lost hours of work.

Mental ill-health often begins in the young, and so the effects can be profound, restricting people at the very time they are exploring their potential and entering some of their most productive years.

Mental health is a massive matter for Australia, not just economically but in terms of widespread suffering, yet it is receiving little attention in this election campaign.

Today's guest in the Election Zone, former Australian of the Year Professor Patrick McGorry, is here to argue mental health is the ''poor relative'' in the health system. He believes ''root and branch'' reform is needed, and that political parties have lost their appetite for improving services, even though there are so many citizens in need.

The full transcript of our interview as well as a short video statement by McGorry are at theage.com.au/federal-politics/the-zone. He will be online for an hour from 1pm today to respond to audience questions and comments.

McGorry was Australian of the Year in 2010 after almost three decades as a researcher, clinician and mental health advocate. He has been particularly interested in young people, and is executive director of Orygen Youth Health, an organisation globally recognised for its innovative work in early intervention and in the prevention and treatment of mental illness. He is also a director of the National Youth Mental Health Foundation (headspace).

McGorry says our politicians are ignoring a ''sleeping giant''. He argues it would be in Australia's interest to significantly increase funding to mental health services. Such an investment would not only prevent suffering but would save the nation billions of dollars.

''It would strengthen the country immeasurably in terms of productivity.''

Of the $30 billion cost of mental health each year, about three-quarters is associated with lost productivity, rather than the direct cost of care and treatment. A report last year by the World Economic Forum found mental illness is now equal to cardiovascular disease as the biggest health threat to the economy in the next 20 years.

McGorry says the mental health budget needs to be doubled in the next decade from about $6 billion a year now spent, a figure that accounts for only about 6 per cent of the total health budget.

''The burden of disease flowing from mental ill-health is about 13 per cent of the total burden of disease, so we're spending about half as much as we should. I would say at least doubling that is what we should aim for.

''Now, I don't think that should necessarily happen in the first year. You would have to build that up slowly over a five to 10-year period, which would be quite reasonable to do. You would see benefits within the first year if we started to do that.''

McGorry's push for reform is not only based on his argument that more spending would yield a rapid and huge return on investment. Ever since his medical studies in the 1970s, he has been motivated by human rights, empathy and compassion.

''I was worried about the raw deal mental health patients were getting, and I suppose that is still what's motivating me. I still see the raw deal that people get, that all of us get. I identify very strongly with the people affected by mental ill-health. It is in all our families or our friends.''

On the day of our interview, a damning study, to which McGorry contributed, of Australian mental health policy for the past 30 years was released.

The study, Obsessive Hope Disorder, was co-ordinated by Adjunct Professor John Mendoza, the former chief executive of the Mental Health Council of Australia and the inaugural chairman of the National Advisory Council on Mental Health.

Launched by former Human Rights and Equal Opportunity Commissioner Brian Burdekin, the study found that, despite 30 years of reform, ''people with a mental illness are still treated like second-class citizens''.

Mendoza said: ''Australia talks a good game when it comes to mental health reform, but in practice what we see repeatedly is inadequate planning, poor implementation and constraints in our system of government.

''It is an outrage that neither major party seems to think mental health is an election issue. Labor said it was their second-term priority, but they have failed to deliver on their promise. The Coalition has been silent on mental health. It is a national shame that our political leaders seem prepared to let people with a mental illness fall by the wayside and suffer.''

McGorry argues Australia has made important progress in the past 30 years, but that the momentum has died. The main changes have been closing asylums and bringing the treatment of mental illness into the mainstream health system.

''This landmark report shows that for the last 30 years we have had momentum behind reform, we have had some initial change and investment, but then it has just gone back to sleep again each time.

''We have replaced the 19th-century models of care with a seriously underdone, under-funded and actually quite stagnant first pass at mainstreaming mental health care within general health care.''

The report found that access to treatment depends on ''your postcode, your income and your determination to find care''.

McGorry has long championed early intervention, an initiative that has put Australia at the forefront of mental health treatment. But, he says, the overall system is failing because mental health patients do not receive the same level or quality of care as patients with physical ailments.

The system struck him as almost ''apartheid'' when he heard of one woman's experience. She found a lump in her breast and went to her doctor. He reacted immediately, ordering a biopsy. She was treated effectively and quickly in an immaculate hospital, and woke surrounded by loved ones and flowers.

''And then about a year or two later she described having the experience of developing quite a severe depressive episode and getting the run-around by the triage system in the same hospital where she was treated for breast cancer, and eventually being admitted after a very distressing series of events into a very sparse and spartan environment. So the contrast between those two was great. She was the same person, but she got completely different access and quality of care.''

A terrible added cost of mental illness is its effect on life expectancy; people with serious mental illness die up to 25 years younger than the average, a gap similar to that experienced by indigenous Australians.

McGorry does not blame clinicians for the failings of the mental health system. He says they have been given a ''mission impossible'', and are struggling in ''a beleaguered and under-funded system with poor morale which is weak politically within the health system''.

But McGorry is optimistic. He believes the stigma of mental illness has been massively reduced, in part through the efforts of beyondblue, a national organisation working to create awareness of depression and anxiety. This greater understanding and acceptance has helped create public demand for better mental health services. But, he says, the situation will not improve unless politicians make it a priority.

''The kind of serious intent for a sea change in reform has not occurred. I compare that with what has happened with disability care and with the education reforms, where tens of billions of dollars have been found to bring those areas up to scratch.

''Mental health in the health system has always been the poor relation. It's funded by about half the amount compared to burden of disease that it really needs,'' McGorry says.

''That is not the case with the rest of the health system. Cancer, diabetes and cardiovascular health are well funded proportionate to the burden of disease and that's a good thing, but mental health needs to have the same sort of support.

''Ordinary Australians are suffering on a daily basis and there is a massive level of public discontent around this issue.''