Autism spectrum disorder (ASD) is the name for a range of similar conditions, including Asperger syndrome, that affect a person's social interaction, communication, interests and behaviour.
In children with ASD, the symptoms are present before three years of age, although a diagnosis can sometimes be made after the age of three.
It's estimated that about 1 in every 100 people in the UK has ASD. More boys are diagnosed with the condition than girls.
There's no "cure" for ASD, but speech and language therapy, occupational therapy, educational support, plus a number of other interventions are available to help children and parents.
Read about help and support available for people with ASD.
Signs and symptoms
People with ASD tend to have problems with social interaction and communication.
In early infancy, some children with ASD don't babble or use other vocal sounds. Older children have problems using non-verbal behaviours to interact with others - for example, they have difficulty with eye contact, facial expressions, body language and gestures. They may give no or brief eye contact and ignore familiar or unfamiliar people.
Children with ASD may also lack awareness of and interest in other children. They'll often either gravitate to older or younger children, rather than interacting with children of the same age. They tend to play alone.
They can find it hard to understand other people's emotions and feelings, and have difficulty starting conversations or taking part in them properly. Language development may be delayed, and a child with ASD won't compensate their lack of language or delayed language skills by using gestures (body language) or facial expressions.
Children with ASD will tend to repeat words or phrases spoken by others (either immediately or later) without formulating their own language, or in parallel to developing their language skills. Some children don't demonstrate imaginative or pretend play, while others will continually repeat the same pretend play.
Some children with ASD like to stick to the same routine and little changes may trigger tantrums. Some children may flap their hand or twist or flick their fingers when they're excited or upset. Others may engage in repetitive activity, such as turning light switches on and off, opening and closing doors, or lining things up.
Children and young people with ASD frequently experience a range of cognitive (thinking), learning, emotional and behavioural problems. For example, they may also have attention deficit hyperactivity disorder (ADHD), anxiety, or depression.
About 70% of children with ASD have a non-verbal IQ below 70. Of these, 50% have a non-verbal IQ below 50. Overall, up to 50% of people with "severe learning difficulties" have an ASD.
Read more about the symptoms of ASD.
Getting a diagnosis
The main features of ASD - problems with social communication and interaction - can often be recognised during early childhood.
Some features of ASD may not become noticeable until a change of situation, such as when the child starts nursery or school.
See your GP or health visitor if you notice any of the signs and symptoms of ASD in your child, or if you're concerned about your child's development. It can also be helpful to discuss your concerns with your child's nursery or school.
Read more about diagnosing ASD.
Caring for someone with ASD
Being a carer isn't an easy role. When you're busy responding to the needs of others, it can affect your emotional and physical energy, and make it easy to forget your own health and mental wellbeing.
If you're caring for someone else, it's important to look after yourself and get as much help as possible. It's in your best interests and those of the person you care for.
Read more about care and support, including information on:
You can also call the Carers Direct helpline on 0300 123 1053.
What causes ASD?
The exact cause of ASD is unknown, but it's thought that several complex genetic and environmental factors are involved.
In the past, some people believed the MMR vaccine caused ASD, but this has been investigated extensively in a number of major studies around the world, involving millions of children, and researchers have found no evidence of a link between MMR and ASD.
Read more about the causes of ASD.
Autism in adults
Some people with ASD had features of the condition as a child, but enter adulthood without ever being diagnosed.
However, getting a diagnosis as an adult can often help a person with ASD and their families understand the condition, and work out what type of advice and support they need.
For example, a number of autism-specific services are available that provide adults with ASD with the help and support they need to live independently and find a job that matches their skills and abilities.
Read more about adults with ASD.
Article provided by NHS Choices