Australia's flagship youth mental health program Headspace is only providing a "small" benefit to clients, a major study has revealed, while the wellbeing of about one in 10 of its patients is going significantly backwards.

Key points: Less than a quarter of Headspace clients significantly improved, report shows

Less than a quarter of Headspace clients significantly improved, report shows Average cost of subsidised session $339

Average cost of subsidised session $339 Results are an average effect over range of different people: Headspace chief

Results are an average effect over range of different people: Headspace chief Averaging results fails to identify which centres perform well: expert

The independent report showed less than a quarter of young people significantly improved, while the cost per visit varied wildly between centres.

Taxpayers subsidised sessions by more than $500 each at some locations, and the average cost per treatment nationwide was $339.

The high-profile network, which celebrated its 10th birthday in October, will have about 110 facilities by 2019.

The University of New South Wales evaluation concluded "Headspace has a small program effect", saying results were marginally better than people getting no treatment or being treated privately.

"While some evaluation findings are mixed, results show that there are small improvements in the mental health of Headspace clients relative to two matched control groups," it said.

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Headspace chief scientific adviser Debra Rickwood said the results were not surprising.

"It's an average effect and an average effect over a large number of young people with a very, very diverse range of presentations," she said.

"So it's not surprising, but obviously you want stronger effects and that's something that will continue to clearly to be worked on and there's a lot of work to be done in this area."

Mixed report card for program

Rachael Laidler says Headspace was a driver for positive change. ( ABC News: David Collins )

Sydney woman Rachael Laidler, 24, had tried to overcome mental health problems — including depression, anxiety and bipolar disorder — since her teenage years.

"I'd been experiencing a lot of really distressing things that I was a bit afraid of and didn't know how to explain," she said.

"And in dealing with that I started drinking really heavily."

Three years ago, a friend recommended she visit a Headspace centre.

"[There were] really fantastic clinicians and some support services who really listened to what I needed," she said.

"That was a phenomenal driver for me in developing my own confidence and my own self-worth."

The report praised the organisation for substantially reducing suicidal thoughts and self-harm by clients.

Service not meeting the needs of everyone

Debra Rickwood says Headspace needs to work on its treatment for drug and alcohol issues. ( ABC News: Steve Ritchie )

But it said the mental health of about one in 10 patients significantly deteriorated during treatment.

It also found there were no "consistent patterns of improvement" in drug and alcohol use, social inclusion or physical health.

"Alcohol and other drugs is a really challenging area and an area that Headspace is very aware that it needs to do more work on," Professor Rickwood said.

The UNSW assessment also warned Headspace was "not yet meeting" the needs of culturally diverse young people.

Each local centre needs its own data: expert

The University of New South Wales study examined the program's effect and cost in the 2013/14 financial year.

It showed the average cost per visit was $339, which included a Headspace grant of nearly $50 million and more than $10 million in Medicare Benefits Scheme (MBS) rebates.

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It said there was a "great diversity" in cost per treatment, suggesting "that more efficient use of government funds may be achievable".

The evaluation said having centres in regional areas with tiny youth populations "may be defensible ... [but] allocation of a centre to areas with very small youth populations is inefficient and results in very high costs per occasion of service".

Sorry, this video has expired Professor questions if youth mental health centre Headspace performing

The Medicare rebate to GPs is $37 per visit while an hour long session with a psychologist attracts $84.40 in MBS funding.

Professor Ian Hickie, co-director of Sydney's Brain and Mind institute which runs the Camperdown Headspace, said more data about Headspace centres was needed so people knew if their local one was performing.

"The danger of averaging things up is you can hide the fact that some centres are doing well but others are not really performing," he said.

"Australians need to know, is this working in the Gippsland, is this working in western Sydney, is it working in northern Queensland?"

During the election campaign, the Coalition promised the funding of existing centres was secure and pledged $20 million for 10 new Headspaces.