The American Psychiatric Association has released the fifth edition of its Diagnostic and Statistical Manual, known as DSM-5.

The $25 million revision happens only once in a generation and comes after nearly two decades of debate, deliberation and change in clinical practice.

The manual is produced primarily as a diagnostic tool for American psychiatrists, helping them to diagnose and treat their patients - and bill them accordingly.

The revision is based on new insights from research since the last version of the manual was published in 1990.

Hoarding, gambling and marijuana withdrawal are among the newly expanded disorders contained in the fifth revision of the 947-page reference book.

Other categories have been redesigned, such as autism spectrum disorder (ASD), which is now the sole title for a range of previously separate diagnoses that used to include Asperger's, autistic disintegrative disorder, and childhood disintegrative disorder.

Aspergers causes problems with communication and socialisation, but unlike more severe forms of autism, it does not involve intellectual disability.

Major changes in DSM-5: Sole category for autism spectrum disorder (ASD)

Sole category for autism spectrum disorder (ASD) New category for disruptive mood dysregulation disorder

New category for disruptive mood dysregulation disorder Newly bereaved can now be diagnosed as depressed

Newly bereaved can now be diagnosed as depressed Gambling addiction included in substance use disorders

Gambling addiction included in substance use disorders Post-traumatic stress disorder classed under trauma and stressor-related disorders

Post-traumatic stress disorder classed under trauma and stressor-related disorders ADHD changed to include youths who show symptoms before age of 12

ADHD changed to include youths who show symptoms before age of 12 Obsessive-compulsive disorder has its own category for the first time - AFP

This makes a move under the autism banner uncomfortable for some who would prefer that it remain in a discrete category.

Children are being diagnosed with ASD at a rate of about one in 100, and while it has been acknowledged for a while that Asperger's is part of the autistic spectrum, it is more than a name change.

Autism Spectrum Australia (ASPECT) psychiatrist Vicki Gibbs says it is a step in the right direction clinically.

She is also in favour of ranking cases on the spectrum from least severe at one, to most severe at three, and attaching specific features to better define the diagnosis.

But the change might yet prove a double-edged sword, because it comes with a tougher set of criteria.

Dr Gibbs says ASPECT's research shows about 20 per cent of children in the future might not be able to jump the bar.

"A number of children with social and communications difficulties who would currently access support services will no longer be eligible," she said.

She says it will be several years before the full effect of the change is clear.

Shades of blue

The prohibition on diagnosing depression straight after bereavement has been lifted in the new manual.

Richard Bryant, a scientia professor in psychology at the University of New South Wales, says it was a hugely contentious debate.

"[There is concern] that we're going to be over-prescribing anti-depressants for example in people who may be grieving, understandably, after bereavement," he said.

On the other hand, a new classification was considered to describe people with grief so constant that it causes serious impairment, suicidal urges and mental illnesses.

Professor Bryant says it was rejected despite strong arguments in favour of a new disorder to support sufferers of persistent grief.

"They're often misdiagnosed, aren't getting the right kind of treatments, and yet that has not been recognised as a disorder," he said.

Battleground of the mind

The re-working of the definition of post-traumatic stress disorder (PTSD) is timely, given the return of many soldiers from Afghanistan and Iraq.

Professor Bryant says the definition has been widened from the traditional focus on fear and anxiety.

Troops from Afghanistan and Iraq are now coming back with a lot of anger, guilt, and shame and it was felt that this needed to be encompassed.

Professor Bryant supports the change because more people will fit under the umbrella of PTSD, but also thinks the broader definition will make research harder.

"In the previous edition, we had 70,000 different ways that that disorder could actually present itself," he said.

"In the new edition, there's 600,000 ways that the disorder can present."

Mixed reviews

Professor Preminder Sachdev from the School of Psychiatry at the University of New South Wales says the influence of the DSM-5 has spread.

"It has been used by insurance companies, sometimes for disability pensions. It has been used by courts for certain determinations and research as well," he said.

But Professor Sachdev, who revised part of the new edition as a member of the Neurocognitive Disorders Work Group, thinks it would be better if its influence was confined.

"It's quite inappropriate sometimes to use the DSM for forensic purposes and [things like] disability insurance, and perhaps we need different versions of the manual for those things."

Others are more strident in their assessment of the manual's worth.

Youth Mental Health advocate Patrick McGorry has described the revision as little more than incremental and desultory change.

"It's a bit of fine tuning around the edges of a classification system that's been in place for a hundred years in some respects," he said.

Professor McGorry, a former Australian of the Year, says while definitions are necessary, real advances in treatment will only come from a new approach such as clinical staging.

"Just a label like schizophrenia or bipolar disorder is not sufficient to actually define treatment selections, so we've got to know what stage the illness is at," he said.

Professor Sachdev also acknowledges the manual's shortcomings as a reflection on psychiatric science in general.

"There are no definitive tests for mental disorders, psychiatrists still rely on signs and symptoms," he said.

However, he says it is the best manual psychiatrists are likely to have for some time.

ABC/AFP