Prof Fiona Stanley, of Perth, said she was "incredibly worried" by trends which showed policy makers failed to find the cause of youth issues but rather just poured money into ineffective treatment.
Prof Stanley was in Dunedin yesterday as a part of the New Zealand International Science Festival.
She has spent her career researching the causes of major childhood diseases.
The diseases affecting today's young people were far more complex than those suffered by earlier generations, as factors such as environment, lifestyle and genetic makeup weighed heavily in a child's chance of getting a disease.
The likes of obesity, asthma, diabetes and mental health and behavioural issues were plaguing our societies, especially in "at risk" communities, she said.
Most had become issues in the past 20 to 30 years, although obesity had had a rapid rise in the past 15 years, she said.
"The growth of childhood obesity has caught us napping."
Mental health problems had also increased significantly, with the number of Australian boys committing suicide four times higher than it was in 1980, even though it was starting to plateau.
Such problems could take up to two generations to reverse, she said.
Maori and Aboriginal communities remained the most at risk, although Maori were significantly better off than Australian indigenous people, she said.
Both groups tended to have multiple problems affecting them and these problems were often compounded by lower living standards and poor access to vital services.
Both countries failed to deliver effective health services for those who were marginalised and by failing to involve indigenous people in these problems they continued to grow.
A solution was to empower communities to help themselves rather than rely on government funds to treat the problems when they arose.
"It is a huge waste spending money on programmes that are too late or totally inappropriate," Prof Stanley said.
"People have got to understand that investing in children and the early parts of life and the early parts of pathways is the best investment we can make."
Local government also needed to have a bigger hand in making decisions and creating child-friendly environments as much of their power had been emasculated by central government which did not know the local issues.
Prof Stanley used the case of sudden infant death syndrome where Aboriginal women were reporting an incidence 10 times higher than non-Aboriginal women until they became involved in educating their own people and the toll was drastically reduced.
Prof Stanley will give a public lecture on whose responsibility it is to improve health today, from 7.30pm, at the College of Education Auditorium.
Tickets can be bought via the sci-fest website (www.scifest.org.nz).
