Autism spectrum disorder (ASD): overview

About autism spectrum disorder

Autism spectrum disorder (ASD) is a brain-based condition – that is, where the brain hasn’t developed in a typical way.

Although no two children with ASD are the same, they all have:

trouble interacting and communicating with others – for example, they might not use eye contact to get someone’s attention, or they can be confused by language and take things literally
narrow interests – for example, they might collect only sticks or play only with cars
repetitive behaviour – for example, they might make repetitive noises like grunts, throat-clearing or squealing, or do things like flicking a light switch repeatedly.

Also, children with ASD are often under-sensitive or over-sensitive to taste, touch, sight and sounds. For example, they might be easily upset by certain sounds, or will eat only foods with a certain texture, or they might seek vibrating objects like the washing machine or flutter fingers to the side of their eyes to watch the light flicker.

What causes autism spectrum disorder?

We don’t know exactly what causes autism spectrum disorder (ASD).

In children with ASD, there might be early brain overgrowth. This means that the brain grows faster than average so that different parts of the brain don’t communicate with each other in a typical way.

Evidence also strongly suggests a genetic basis to ASD. But it’s unlikely that one specific gene is responsible for ASD. It’s more likely that several genes combine and act together. Researchers have found many possible genes that might play a role in the development of ASD.

There’s no one answer to the question of what causes ASD. But it’s clear that what parents do or don’t do doesn’t cause ASD in their child.

Autism spectrum disorder: signs

It’s common to see early signs of autism spectrum disorder (ASD) in a child’s first two years. And in these years, it’s especially important to watch children’s social communication development.

For example, in the first year of life, parents of babies later diagnosed with ASD notice their child’s lack of interest in other people. Many of these babies don’t make eye contact with their parents while being held or during nappy changes. The lack of other behaviour like smiling and gestures is also a sign that a child isn’t developing in a typical way.

In the first two years, other signs might be a child not responding to his name, or focusing narrowly on activities like lining up toys.

Signs of ASD become more noticeable in the toddler years, as children are expected to start talking and playing with other children. Children with ASD might not be interested in playing with other children, or might speak in an unusual way – for example, in a monotone.

Signs of ASD in older children and teenagers might become noticeable when a child has difficulty adjusting to new social situations in a school environment – for example, staying on task, understanding and following instructions, making friends, and having age-appropriate interests.

Autism spectrum disorder diagnosis

Autism spectrum disorder (ASD) can be diagnosed from two years of age.

Diagnosis usually involves many specialists and professionals testing and assessing a child – this is called a multidisciplinary assessment.

A multidisciplinary team usually includes a paediatrician or child psychiatrist, a psychologist and a speech pathologist. It might also include other professionals like an occupational therapist.

There’s no single test for ASD. Instead, ASD diagnosis is based on:

watching how a child plays and interacts with others – that is, how a child is developing now
interviewing parents
reviewing a child’s developmental history – that is, how a child has developed in the past.

Children who are diagnosed with ASD get a description of how severe their symptoms are and the amount of support they need. This ranges from ‘needing support’ to ‘needing very substantial support’.

Health professionals will also assess children’s language and cognitive abilities.

Children who show difficulties only in social communication might be diagnosed with social communication disorder, rather than ASD.

Concerned about your child’s development: what to do

If you’re concerned about your child’s development, talk to your child and family health nurse or GP about a developmental assessment. Getting an assessment and diagnosis is the first step to helping your child and getting services and programs suited to your child’s needs.

It’s important to get help and support as soon as possible. The sooner children get early intervention services, the more effective these services can be.

I wish I’d known that autism looks different in every child. A friend’s little boy was diagnosed with autism but he was very different from my son – her boy had no language and lost all eye contact with others. Although I knew something was wrong with my son, I didn’t think it was autism because not only did he have some words, he would look at me and smile.
– Jenny, mother of Alexander, aged five

Different types of autism spectrum disorder

In May 2013, the criteria that health professionals use to diagnose autism spectrum disorder (ASD) changed. This was when the 5th edition of the Diagnostic and statistical manual of mental disorders, or DSM-5, was published.

Before 2013, professionals diagnosed different types of ASD – autistic disorder, Asperger’s disorder (also called Asperger’s syndrome), and pervasive developmental disorder – not otherwise specified (PDD–NOS).

Under the DSM-5, there’s just ASD.