What is autism spectrum disorder (ASD)?

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General information about autism spectrum disorder, its possible causes, and how it is diagnosed. Also discusses related conditions such as pervasive developmental disorder and Asperger's syndrome.

Key points

  • Autism spectrum disorder (also called ASD) refers to a specific set of behavioural and developmental issues affecting your child's communication, social and play skills.
  • Every child with ASD is unique and has their own combination of characteristics.
  • A diagnosis of ASD is based on what a medical doctor or psychologist observes and learns about your child’s behaviour and development in the early years.
  • ASD is not a mental illness.
  • No one specific cause of ASD is known.
  • There is no medical cure for the difference in the brain that cause ASD, but with the right treatment, some behaviours can be changed.

Autism spectrum disorder affects your child's social behaviour, communication, and play behaviour and interests. This page explains general characteristics of ASD, how ASD is diagnosed, and common misconceptions about its causes.

What is autism spectrum disorder?

Autism spectrum disorder, also called ASD, is the name used for a specific set of behavioural and developmental problems and the challenges that go with them. A diagnosis of ASD means that your child’s communication, social, and play skills are affected in some way.

The word spectrum in ASD means that every child is unique and has their own combination of characteristics. These combine to give them a distinct social communication and behaviour profile.

As your child grows and develops, the nature or expression of these problems and challenges may change based on their biology and environmental experience. Usually a person with ASD will have some form of social and/or behavioural differences for the whole of their life.

A diagnosis of ASD is based on what a medical doctor or psychologist observes and learns about your child’s behaviour and development in the early years. That person needs to find out about your child’s history, particularly the early years, by talking to you and anyone else who knows them well.

Other names for ASD

Often different professionals use different names to describe ASD and in the beginning this can cause confusion. Some names you may hear used to describe your child are:

  • Pervasive developmental disorder (PDD)
  • Pervasive developmental disorder-not otherwise specified (PDD-NOS)
  • Asperger syndrome
  • High functioning autism

All of these names fall under the term ASD. We use the terms autism, autism spectrum disorder, or ASD in this resource centre.

The diagnosis of ASD

Parents, family, teachers, and the general public are often confused by a diagnosis of ASD. Many parents say, “My child can’t be autistic because they are affectionate, makes eye contact, likes to be hugged, doesn’t bang their head, etc.”

Some children with ASD may not make any eye contact; other children may make eye contact some of the time while other children may seem to stare. Some children with ASD like to be hugged but others do not. As much as children with ASD share similar characteristics they also can be very different from each other. Like all children, children with ASD have different likes and dislikes.

A diagnosis of ASD means that your child’s development will look different in three main areas:

  • social behaviour
  • communication
  • play: behaviour and interests are repetitive or limited

How common is ASD?

ASD is the most common developmental condition. Based on Canadian research by Fombonne and colleagues from 2006, one out of every 165 people have ASD. More recent US data (from the Centers for Disease Control, 2009) show that this incidence may be closer to one in 100. Four out of five people with ASD are male. ASD affects people from all parts of the world. It affects people of every social economic background and race.

What causes ASD?

There are many studies looking at the causes of ASD. Although no one specific cause is known, current studies suggest that ASD may be related to differences in the brain.

In some families, there appears to be a pattern of ASD or related differences in more than one member of the family. This suggests there is a genetic basis to the disorder. At this time, no single gene has been directly linked to ASD. In fact, ASD is most likely the result of a complex interaction of several genes. Research in this area is ongoing.

Several older ideas about the cause of ASD have now been proven NOT to be true. At one time, parents were blamed for their child’s difficulties. For example,

  • Children with ASD were believed to have a difficult time forming relationships with others because their parents were not loving enough.
  • Mothers were particularly thought to be at fault. They were called “refrigerator mothers.”

For many years, such ideas stopped us from understanding ASD.

We now know that the brain of a child with ASD develops differently from conception. We know that:

  • ASD is not a mental illness.
  • Children with ASD are not unruly kids who choose to misbehave.
  • Bad parenting does not cause ASD.

Is there a cure for ASD?

There is no medical cure for the differences in the brain that cause ASD. However, because we understand the brain and ASD so much better now, we may be able to influence how the brain develops and works.

Slowly we are finding ways to help people deal with different characteristics of ASD. With the right treatment, some behaviours can be changed. But most children and adults with ASD will always have some characteristics of ASD for the rest of their lives.

What does the future hold for your child?

Parents of children with ASD often ask about their child’s future. They wonder if their child will date or marry, have a job, or live on their own independently.

We cannot predict the future for any child. But the stories of adults with ASD offer hope that many people with ASD can have full and satisfying lives.

Last updated: March 9th 2009