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Diagnostic Assessments for Autism

What is autism ?

Autism is a lifelong developmental condition that affects how people understand and interact with the world around them. It is referred to as a spectrum condition because of the wide range of presentations seen in autistic individuals; for example, some people may also have a co-occurring learning disability. However, all people who are considered to be autistic will share common difficulties, although these difficulties may affect them in different ways.  The broad areas in which all autistic people will experience difficulties in are: social interaction and social communication; and routines, repetitive behaviours and intense interests.

Diagnostic assessments

In order to be diagnosed as autistic, people need to be assessed by professionals with specialist training in assessing for autism. The assessments usually include a detailed history, observations, and gathering information from one or more people who know the person being assessed (e.g., a parent). Many people are diagnosed as autistic in childhood, but more people are seeking assessments as adults, partly due to increased awareness of the autism spectrum.

If you are considering self-referring for a diagnostic assessment of autism, or if you are a professional considering making a referral on behalf of someone, please read the following information. The information tells you about the diagnostic criteria of autism and the assessment process.

Diagnostic criteria:

  • For a diagnosis of autism to be made a person needs to have significant difficulties in social interaction & communication and restricted and repetitive behaviours, interests or activities – see table below for examples of the kinds of difficulties people may experience.
  • These difficulties have to be lifelong. This means that they will have started in childhood.
  • These difficulties need to be having an impact on multiple aspects of your life (not just creating problems in one situation).
  • These are some examples. You do not need to experience all of these difficulties, but you do need to experience differences across both columns:  


Social interaction and social communication
Restricted and repetitive behaviours, interests or activities

Difficulties in making and/or maintaining relationships

Highly focused, all-encompassing interests

Difficulties in understanding and managing emotions

Excessive adherence to routines to an unusual degree

Problems understanding how other people think or feel

Inflexible thinking (black and white thinking)

Difficulties understanding social rules

Difficulties coping with change

Unusual speech

Repetitive behaviour or rituals

Repetitive speech

Strong adherence to rules

Difficulties with eye contact

Repetitive or stereotyped movements

Reduced facial expression or gesturing

Over or under-sensitivity to sensory aspects of the environment

Difficulties communicating with others

Noticing small details, patterns or sounds that other people do not notice

Problems in understanding, such as taking things literally

Difficulties being able to read other people’s non-verbal communication


Process information:

  • We are currently seeing people on our main waiting list who were referred 24 months ago (September 2023). However, due to significant demand for assessments and insufficient resource to meet the demand, the waiting times are increasing so the wait may be longer than 24 months.
  • Prior to the full assessment, two pre-assessment questionnaires will be sent out to be completed by the person being assessed and by someone who knows them well.
  • The assessment includes 1 -2 appointments with two Clinicians. The full assessment may take up to 5 hours.
  • Many people referred for assessment do not meet the diagnostic criteria despite presenting with traits/ behaviours that overlap with autism. We recognise that it can be very disappointing for some people when they do not receive a diagnosis.

Triage Clinic

From the 1st September 2022, all individuals who have new referrals accepted by the service for autism diagnostic assessments will be invited to attend our triage clinic. 

Information for people attending a triage appointment:

  • Prior to being offered a triage appointment, you will be asked to return a questionnaire. 
  • You will then be seen at the triage clinic by two experienced clinicians who will determine whether a full diagnostic assessment of autism is indicated. 
  • If further assessment is indicated, you will be added to the waiting list for a full diagnostic assessment. 
  • If further assessment is not indicated, you will be discharged from the Integrated Autism Service and directed to other services or resources, as required. 

Please note, the triage clinic will offer rapid access to the service; however, should individuals need further assessment the waiting time is still likely to be around 24 months at the present time.  We are hopeful that the triage clinic will reduce the waiting times in the long term. 

After reading this information if you wish to request an assessment of autism, please complete this referral form with as much information as you are able to and return it to the IAS. If you need help to complete the form then please let us know. For professionals considering referring to the Integrated Autism Service, please also refer to our diagnostic pathway for more information.

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