Autism spectrum disorder

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Autism spectrum disorder (ASD) is a brain-based condition – where the brain hasn’t developed in a typical way. Although no two children with ASD are the same, they all face challenges in interacting and communicating with others.

• What causes autism spectrum disorder (ASD)?
• ASD: difficulties and abilities
• Different types of ASD
• Diagnosis
• Other ASD facts

What causes autism spectrum disorder (ASD)?

We don’t know exactly what causes ASD. But the latest research shows that in children with ASD:

• There is early brain overgrowth (the brain grows faster than average).
• Different parts of the brain aren’t communicating with each other in a typical way.

Also, evidence strongly suggests a genetic basis to ASD. That is, the condition may come from the complex interaction of several genes involved in brain development.

Read more about what causes autism.

ASD: difficulties and abilities

Children with ASD have a wide range of difficulties and abilities. In fact, some have very impressive skills and strengths. One child with ASD might know lots of words and have a very good memory. Other children might respond mostly to things they can see, making them good at completing puzzles and sorting objects by shape and colour.

By about the age of three, however, all children with ASD will show difficulties in three main areas.

Social interaction and relationships
Children with ASD will appear to be uninterested in social contact with others. They:

• might not respond when people speak or gesture towards them, even when their names are called out
• often make little eye contact with others and usually won’t copy other people’s actions, like clapping or waving
• usually don’t share interests with others, rarely pointing at anything or showing interest in giving or sharing
• are not very interested in chatting or playing, especially with other children.

Communication and language
Children with ASD usually take longer than the average child to learn language. That means knowing fewer words, not using their words to communicate with others, or not speaking at all.

Children with ASD will find it hard to comprehend language, so understanding simple instructions and social norms can be difficult.

When children with ASD do have language skills, they:

• will talk about their own special interests, and rarely use language skills to communicate with others
• might focus on categorising everything around them, such as labelling all their toy trains
• might echo what they hear, repeating patterns of words without attaching any meaning to them
• rarely use non-verbal gestures, like nodding their heads or hand gestures, to communicate.

Repetitive behaviour and routines
Even from a young age, children with ASD will often prefer the same routines – feeding, sleeping or leaving the house needs to be done the same way every time. They might be upset by changes like moving furniture or altering the usual familiar travel route.

Many children with ASD also like to repeat behaviour, sometimes in an obsessive way, like lining their toys up in a particular way over and over again. Younger children might like to collect things like twigs, string or balls. They will clutch tightly to their favourite objects and become upset if they are removed.

Older children with ASD might have very narrow and intense interests. For example, they might be interested in trains, always choosing a toy train over other toys, labelling every train in their surroundings, and insisting on watching cartoon train videos over and over. If they have strong verbal skills, they might talk only about trains.

Different types of ASD

Autistic disorder (or autism)
Children with this diagnosis show that they have difficulties with social relationships, verbal and nonverbal communication and repetitive behaviour. They might also have associated developmental delays – this means they haven’t reached certain milestones for their age.

Read more on autistic disorder.

Asperger’s disorder
Children diagnosed with Asperger’s disorder generally don’t have developmental delays, and might have good language skills. They might have:

• unusual language patterns (such as speaking in a very formal way with a monotone voice)
• difficulties with social relationships
• narrow interests (so they can become easily fixated on a favourite topic).

Read more on Asperger’s disorder.

Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS)
Children are diagnosed with PDD–NOS when they have some but not all of the symptoms needed for a diagnosis of autistic disorder or Asperger’s disorder.

Read more on PDD–NOS.

Diagnosis

Diagnosis of ASD is based on a child not reaching certain age-based developmental milestones, because there are no other physical characteristics of the condition. The first sign of ASD that parents overwhelmingly notice is their child’s lack of interest in what is going on around. If you're concerned about your child’s development, talk to your health care provider about a developmental assessment. Finding out for sure is the first step to helping your child and accessing services and programs suited to your child’s needs.

A paediatrician, psychiatrist, psychologist, or other trained professional in ASD, can diagnose ASD in a child using a combination of behavioural tests (watching the child play and interact) and parent interviews about their child’s development.

Read more about diagnosis.

Other ASD facts

The prevalence of ASD has risen since the 1990s. Research suggests that the apparent increase is at least partly because of:

• increased awareness about ASD, so more cases are identified
• changes in the criteria when diagnosing ASD.

Most studies focus on measuring the prevalence of ASD in general or of autistic disorder – fewer focus on Asperger’s disorder or PDD–NOS.

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