When a rewrite of psychiatry's diagnostic guide is released in San Francisco later this month, it will include a revised definition of autism, expanding it into a full spectrum disorder that can range from mild to heartbreakingly severe.

This new and already controversial fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) will add the term "autism spectrum disorder," which is currently used by many experts.

Asperger's disorder or syndrome — a condition where people often have high intelligence and vast knowledge of narrow subjects but lack social skills — will be dropped and incorporated under the umbrella austism-spectrum diagnosis.

The new definition will incorporate a wide range of symptoms that range from mild to severe, psychiatrists say.

In a child, the signs can include ritualistic physical activity like spinning or flapping arms wildly in the air, expressing frustration by pushing a teacher or teacher's aide aside, or retreating into playing computer games instead of spending time with other children.

Autism is now felt to be a common neurological disorder. Estimates of the number of people afffected by it range from one in 200 to one in 300, according to a study by the National Epidemiological Database for the Study of Autism in Canada.

In the U.S., the Centres for Disease Control and Prevention estimated last year that one in 88 children has been identified with autism spectrum disorder (ASD). That represents a 23 per cent increase since 2009 and a 78 per cent rise since 2007.

"Some of the increase is due to the way children are identified, diagnosed and served in their local communities, although exactly how much is due to these factors is unknown," the CDC said.

ASDs are nearly five times more common in boys than in girls, the CDC noted.

When was autism identified?

Autism was first described in the early 1940s by two doctors who were working independently of each other. Leo Kanner and Hans Asperger identified a common set of symptoms they found among the children they were studying.

Both used the word autism — from the Greek word for self — to describe these children, who seemed enclosed in their own solitary worlds.

Kanner was a child psychologist at Johns Hopkins Hospital in Baltimore, Md. Asperger, whose work was published a year after Kanner's, was a pediatrician in Vienna.

Since Asperger (unlike Kanner) included people who had average to high IQs in his definition, the scientific community reserved "Asperger syndrome" to describe prodigies and certain high-functioning people with an autistic disorder.

It has been suggested by some that Microsoft founder Bill Gates exhibits the characteristics of Asperger syndrome. He has often been seen rocking and tends to speak in monotones — both habits acknowledged to be symptoms.

What is autism?

The term has been used in two ways:

  • To refer specifically to autistic disorder (classic autism)
  • To refer to five autism spectrum disorders described under the diagnostic category of pervasive developmental disorders (PDD) that appear in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) of the American Psychiatric Association.

Debating a label

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, due out at the 2013 annual meeting of the American Psychiatric Association in San Francisco from May 18 to 22, will eliminate Asperger disorder as a separate condition.

Psychologists who advocated for the change said there is a range in autism, and that the umbrella term —autism spectrum disorder —is appropriate to cover the range from high-functioning to profoundly disabling.

Some critics likened the proposal to lumping all cancers together, when each type of the disease is diagnosed, assessed and treated differently. They worried that including Asperger's under ASD could mean people with the syndrome will fall through the cracks.

Autism spectrum disorder is considered a neurological condition that affects the way the brain functions and results in difficulties with communication and social interaction. People with the disorder also exhibit unusual patterns of behaviour, activities and interests.

People with ASD could share certain behavioural, social and communication characteristics, but they can vary widely in the effect it has on their day-to-day lives.

Some people can function well, others are locked in a world of their own.

At its most severe, people with autism can exhibit extremely repetitive and unusual behaviours like self-injury and aggression. If untreated, the symptoms can be very persistent and difficult to change.

But in its mildest forms, autism is more like a personality difference linked to difficulties in understanding social conventions.

What are some of the symptoms of ASD?

There is no single symptom that would lead to a diagnosis of autism. But someone who shows a number of the following characteristics and behaviours would likely be diagnosed with an ASD:

  • Shows no interest in other people
  • May be interested in people, but does not know how to talk, interact with or relate to them
  • Has difficulty initiating and maintaining a conversation.
  • Is slow developing speech and language skills, which may begin to develop and then be lost, or may never develop fully.
  • Has difficulty interpreting non-verbal communication such as social distance cues, or the use of gestures and facial cues, like smiles, that most of us take for granted.
  • Repeats ritualistic actions such as spinning, rocking, staring, finger flapping, and hitting oneself.
  • Has restricted interests and seemingly odd habits, like focusing obsessively on only one thing, idea or activity.

As well, people with ASD may have secondary problems such as:

  • Neurological disorders including epilepsy.
  • Gastro-intestinal problems.
  • Fine and gross motor deficits.
  • Anxiety and depression.

Children with ASD develop motor, language, cognitive and social skills at different rates from other children their age. For instance, they may be very good at solving math problems but have great difficulty making friends or talking.

How is ASD diagnosed?

There is no single test that will confirm that someone has an ASD. A diagnosis is based on the number and pattern of typical characteristics and on the observation of specific behaviours and disabilities.

Someone with a mild case could go undiagnosed for years, and it might only be detected when the person goes through a crisis that brings contact with professionals who are able to recognize the disorder.

What causes ASD?

Nobody's certain. It's generally accepted that autism is a neurological disorder. Research is focusing on genetics, differences in brain function, environmental factors, viral infections and immune responses and deficiencies.

How is autism treated?

Some people with mild forms of autism may never need treatment. They function well and may even excel in life.

However, those with severe forms of the disorder are unable to function and may benefit from active therapy. There are several ways people with autism are treated and there is plenty of debate over what kinds of treatments offer the most success.

Applied Behavioural Analysis (ABA) and Intensive Behavioural Intervention (IBI) are designed to actively engage children with communication, socialization, learning and behavioural problems.

ABA can be extremely expensive as it involves one-on-one teaching for up to 40 hours a week. Costs range from $30,000 to $80,000 a year, according to the Autism Society Canada.

IBI is also an intensive program that can involve either one-on-one therapy or sessions with small groups. Other types of therapy can combine elements of physiotherapy, counselling, development of motor and language skills, diet and medication.