Dr Youlden, who founded the multi-disciplinary, allied health organisation Educare 20 years ago, said while her private practice had received employment inquiries from psychologists skilled at working with adults, the same could not be said of her peers who had experience working with children.

"Further there is a massive shortage of psychologists who are trained and experienced to do diagnostic assessment of children with developmental and cognitive difficulties - that is, Autism Spectrum Disorder, Attention Deficit Hyperactivity Disorder, learning difficulties," she said.

Dr Youlden said the lack of affordable services for families also remained a challenge in her sector.

"There should be more government supported family support services, where [organisations such as Educare] can refer people to them, for families who need regular fortnightly to monthly appointments, so there is no cost involved," she said.

"In the private sector we need to have a gap payment over and above the Medicare rebate, across the board."

Dr Youlden believes families should be linked to a family support service from the moment a child is born, pointing to the reportings of the Productivity Commission's inquiry into mental illness highlighting the importance of early intervention.

"Whether it is family therapy or counselling, it would be so there would be someone the family could contact. In an ideal world, someone could see the family at least every six months, maybe every three months," she says.

"That way the problems can be picked up early and the necessary intervention provided. Also, parenting strategies work best when they are implemented with children from a very young age."

In 2018, Autism Spectrum Australia revised its autism prevalence rates from 1 in 100 to an estimated 1 in 70 people in Australia on the autism spectrum. This led to an increase of 40 per cent in prevalence, with about 353,880 people nation-wide formally diagnosed on the spectrum.

The Australian Psychological Society could not confirm or deny Dr Youlden's concerns, saying factors impacting on the availability of psychologists included desired employment location, working hours, area of interest or specialisation and lifestyle.

In its response to the Productivity Commission, the APS urged the federal government to develop a national benchmark for school-based psychologist to student ratios.

APS recommends a ratio of one psychologist to 500 students, in line with the 2010 recommendation of the NSW Coroner in response to a student suicide at school and the ratio that was implemented in NSW in July this year.

"While the APS welcomes the [commission's] recommendation of a 'wellbeing leader' in every school, we maintain our position that a psychologist should also be placed in every government school," APS president Ros Knight said.

"A raft of mental health issues are common in children and young people, and qualified psychologists are urgently needed in all Australian schools to address the crisis."

Ms Knight said psychologists employed in schools were able to work at a whole-of-school level on programs to prevent mental health disorders.

"They are also able to identify children at risk of mental health issues and intervene early to prevent serious problems developing," she said.

"Psychologists are also trained to assess children for learning difficulties or intellectual disability, and work with teachers and families to support children with behavioural issues."

Ms Knight said psychologists could support teachers and principals, particularly during challenging times.

APS data shows one in seven children and young people aged four to 17 are affected by mental health issues and 50 per cent of lifelong mental health issues start before the age of 14 years.

"School is the appropriate setting to catch early signs and provide early intervention - evidence shows the link between mental health and student outcomes," Ms Knight said.

"More psychologists in schools will mean children who need extra help will get it, and won't be left behind."