Illustration: Matt Golding.

Illustration: Matt Golding.

THREE-YEAR-OLDS will be screened for early signs of mental illness in a new federal government program that uses behaviours such as sleeping with the light on, having temper tantrums or extreme shyness as signs of possible psychological problems.

The ''Healthy Kids Check'' will be predominantly conducted by GPs, with children who show troubling behaviour referred to psychologists or paediatricians.

The program is expected to identify more than 27,000 children who the government claims may benefit from additional support, but who some doctors claim may be wrongly labelled as having a mental illness. While the aim is to prevent mental disorders - 50 per cent of which start in childhood - the Australian Medical Association and some mental health experts fear children may be misdiagnosed or given psychiatric drugs unnecessarily.

''We have to be careful we don't medicalise normal behaviour and that's a real caution with children,'' AMA president Steve Hambleton told The Sunday Age. ''There are genuine kids who need extra support to help them integrate into normal kindergartens and classrooms, and a lot of the funding for that is driven by diagnoses, so there's a perverse incentive to diagnose conditions like autism. There are kids who need it but we don't want to make normal kids abnormal.''

However, Frank Oberklaid, director of the Centre for Community Child Health at Melbourne's Royal Children's Hospital and chairman of the expert committee appointed by Minister for Mental Health Mark Butler to develop the check, said their priority was to ''first do no harm''.

''The critics are worried that we're going to slap diagnoses on three-year-olds and treat them with drugs, but this is not the point of the exercise,'' Professor Oberklaid said.

''Many parents and preschool teachers face behaviours in children that are challenging and cause stress and distress. Thankfully many of these are transient, but we can't predict in a particular child which ones are going to disappear and which ones are going to go on and cause mental health problems. What we're really doing is having a more systematic way of finding out those kids who are causing difficulties and doing something about it.''

The test, although not compulsory, will form part of a physical check for developmental problems such as hearing, eyesight and allergies. Previously it was conducted on four-year-olds but has been brought forward a year and, for the first time, will include social and emotional wellbeing screening.

Doctors will receive extra training before the check is introduced in the next financial year.

Announced as part of last year's budget, The Sunday Age has obtained the first details of the $11 million four-year program.

A checklist of potentially troubling behaviours for GPs to screen for is being finalised and Professor Oberklaid said it would likely include ''externalising'' behaviours such as aggression, difficulty with impulse control and frustration, and trouble interacting with other children.

''We'll also look at internalising disorders. Three and four-year-olds can get anxious as well. Children who have persistent fears, extreme levels of shyness, won't go to bed without the light on, won't sleep in their own bed … We want to begin a narrative that says Johnny or Jane is exhibiting these behaviours that cause concern to parents and then put in place strategies to help parents and early childhood professionals deal with them, and if they disappear that's terrific. If they don't, then at least those kids will have been picked up by the system,'' he said.

Professor Allen Frances, a visiting American psychiatrist who chaired the last edition of the ''bible of psychiatry'' - the Diagnostic and Statistical Manual of Mental Disorders - said childhood epidemics of autism, bipolar disorder and attention deficit disorder had begun with well-intentioned doctors intervening early, but led to widespread mislabelling and medicating.

''Many kids have developmental problems that disappear by themselves and it's very difficult to evaluate in any given child whether the improvement resulted from treatment or just growing up. Before you have a mass national experiment like this, it needs to be carefully piloted to make sure that the harms are not going to be greater than the risks,'' Professor Frances said.

Anna Sexton from East Brunswick has children aged three, five and six who all sleep with the hallway light on. She said she was concerned this behaviour would be viewed as abnormal under the tests. ''I can appreciate the benefit of early intervention if it's warranted but my gut reaction is one of concern for over-diagnosis,'' she said.

However, Chris Tanti, chief executive of headspace, the youth national mental health foundation, which supports 12 to 25-year-olds, said early intervention did not automatically lead to children being labelled. While 83 per cent of the 43,000 young people who visited headspace between 2009-10 and 2010-11 displayed signs of mental illness, only 19 per cent went on to receive a diagnosis.