Diagnosing autism spectrum disorder 

In most cases, parents notice the symptoms of autism spectrum disorder (ASD) when their child is around two or three years old.

In some instances, mild cases may not be detected until adulthood.

Diagnosing ASD in children

If you are worried about your child's development, visit your GP. If appropriate, they can refer you to a health professional or team who may specialise in diagnosing ASD, or someone who has access to such a team. They will make a more in-depth assessment.

This health professional may be:

  • a psychologist – a health professional with a psychology degree, plus further training and qualifications in psychology
  • a psychiatrist – a medically qualified doctor with further training in psychiatry
  • a paediatrician – a doctor who specialises in treating children
  • a speech and language therapist – a specialist in recognising and treating communication problems

Some local health authorities now use multidisciplinary teams. These are made up of a combination of professionals who work together to make an assessment.


There are no individual tests to confirm a diagnosis of ASD, a diagnosis is instead based on the range of features your child is showing.

The type of assessment carried out often depends on things such as access to additional information (for example nursery or school records) and the skills of the professional or team seeing your child.

A detailed assessment for ASD may or may not be required. If one is carried out, this will involve a number of steps, which are explained below.

For most children:

  • Any existing information about your child's development, health and behaviour may be sought from relevant people, such as your GP, nursery or school staff.
  • A detailed physical examination will be carried out to rule out possible physical causes of your child's symptoms, and some children may be referred for further tests, such as testing their blood for genetic conditions with similar features to ASD.

In addition, for some children:

  • You may be asked to attend a series of interviews so a detailed family history and the history of your child's development can be drawn up.
  • Your child may be asked to attend a series of appointments so that specific skills and activities can be observed and assessed. This is known as a focused observation. Focused observation looks at language, behaviour, the pattern of your child's thinking (known as their cognitive ability) and how they interact with others.

Once this process is complete, a diagnosis of ASD may be confirmed. If a diagnosis of ASD is not confirmed during an assessment, but your child later develops more significant signs of the condition, a re-assessment may be carried out.

After diagnosis

Parents may react in different ways when ASD has been confirmed. Some parents feel relieved because they now understand the reasons behind their child's behaviour and can begin to treat them.

Other parents feel an immense sense of shock and disbelief, as they are naturally worried about what the diagnosis means for their child's future.

However, the diagnosis offers an insight into your child's individuality and personality. In turn, it gives you a chance to guide their development and growth.

When a child is diagnosed with ASD, many parents are keen to find out as much as they can about the condition. The National Autistic Society has an excellent range of resources and advice on its website.

You can also the read the National Institute for Health and Care Excellence (NICE) guidelines on diagnosing autism in children and young people and managing autism in children and young people.

Diagnosis of ASD in adults

Some people with ASD grow up without their condition being recognised. But it's never too late to get a diagnosis. Some people may be scared of being diagnosed because they feel it will 'label' them and lower other people's expectations of them. But there are several advantages.

Getting a diagnosis of ASD will help people with the condition and their families understand ASD and decide what sort of support they need. A diagnosis may also make it easier to access autism-specific services and claim benefits.

See your GP if you think you may have ASD and ask them to refer you to a psychiatrist or clinical psychologist. The National Autistic Society website has information on the process of being diagnosed with ASD for adults.

If you're already seeing a specialist for other reasons, you may want to ask them for a referral instead. However, some local NHS authorities do not provide NHS funding for diagnosing ASD in adults.

Read more about diagnosing autism spectrum disorder in adults and advice for adults with autism spectrum disorder. You can also read the NICE guidelines on the recognition, referral, diagnosis and management of adults on the autism spectrum.

Autism spectrum disorder: Graeme’s story

Graeme took a dyslexia test at the age of 24, which showed he had signs of autism. He describes how he was finally diagnosed with Asperger syndrome and what the diagnosis meant to him.

Media last reviewed: 31/03/2014

Next review due: 31/03/2016

Page last reviewed: 18/12/2013

Next review due: 18/12/2015