Autism Diagnostic Research Centre
Tel: 023 8020 2631

Diagnosis assessment


Using standardised, replicable measures, the Diagnostic Assessment involves looking at:

  • developmental history
  • motor skills
  • language development
  • areas of specialist interest
  • social development

ADRC uses the International Classification of Diseases – 10th edition (ICD-10) criteria to make a formal diagnosis.

A diagnosis of Autism Spectrum Disorder may be given where there is evidence of qualitative impairments in social interaction and in verbal and nonverbal communication, and restricted, repetitive and/or stereotypic behaviours, present from at least the age of three years.

For this reason, the patient will be asked to attend, whenever possible, with someone who knows them well – such as a parent or other relative. This is an important part of the diagnostic assessment.

A careful history is obtained, including information related to pregnancy and neonatal period, early development and characteristics of development, a history of the onset and recognition of difficulties plus any relevant medical and family history.

The Diagnostic Assessment will also include observation in structured and unstructured times during the day e.g. during the lunch break.

Autism and adults

Autistic adults face a range of challenges distinct from those encountered by children. These include issues relating to living without a diagnosis, as well as barriers to assessment and support. The film below outlines some of these issues, including those encountered by GPs, the most common point of referral for adult assessments. In this section, Dr. Stacey Munro, a GP who has referred a number of patients to ADRC, discusses these challenges.

Read the transcript of the video

"Autism spectrum conditions, are neurodevelopment conditions, affecting social, communicative and sensory experience and function. While the majority of people are diagnosed in childhood, many continue into adulthood, without a diagnosis. This group face a range of barriers to effective diagnosis and support, including lack of recognition by non-specialist professionals. For adults in particular, getting the right diagnosis and support can have a significant impact on wellbeing. The Autism diagnostic research centre offers a service designed specifically for this group." >Dr. Stacey Munro (General Practitioner) "As a GP I have come across several patients who have not been diagnosed with autism as a child, and have reached adulthood without having a diagnosis established. For those patients life has been very difficult. Some of them have been mislabeled as having depression or psychotic illness, and therefore have been given treatment that isn't going to be effective, and could potentially be harmful. In addition, people that care for them, their family and friends, and any carers that they may have, have also not been given guidance on how to approach any challenges that their behaviour may cause. I've seen the differences that having a diagnosis can make to patients. It enables them to access interventions and services, in order for them to have a more fulfilled and productive life. For me as a GP, my role is to be able to refer my patients for something that's going to make a difference to them. One of the barriers to diagnosis is the lack of recognition of the condition, particularly among adults who don't have an associated learning disablility. A specialist service, and having access to a specialist service, can only help us to recognise that this condition exists, and to help to provide us with information about how to recognise it."

Dr. Stacey Munro, GP

Overview of the diagnostic process for adults

For adults, diagnosis presents a number of issues distinct from those typically involved in child assessments. In the video below, Dr. Tony Brown (Consultant Clinical Psychologist) describes the measures used in the assessment, and how these relate to the particularities of adult assessment.

Read the transcript of the video

"One of the measures that we use is the Autism Diagnostic Interview Revised (ADI-R), and this is made up of several components. One of these is a measure of the developmental history, which is essential, given that autism is a pervasive developmental disorder. The other main components are measures of qualitative impairments in communication, social interaction, and the presence of repetitive, ritualistic and stereotypic patterns of behaviour.

We are able to generate this information from informants, and preferrably from parents. On occasions that is not possible, when individuals are of an age where parents are not around anymore, or when individuals do not want their parents to be involved. However, further information can be generated through the use of the Autism Diagnostic Observation Schedule. This is a tool that has been used with children but also adults, to allow for environmental manipulation, in that prompts and presses can be put into place, to allow for certain areas to be picked up, i.e. being social interaction, communication, and the presence of repetitive, ritualistic and stereotypic patterns of behaviour.

These measures are collated, and the team work as a whole to critique and look at the data, for the purposes of determining whether there is a positive diagnosis to be confirmed, whether there is a differential diagnosis, or whether there is a dual diagnosis. Overall, diagnosing autism is relatively easy, but it is cosiderably easier to get it wrong. That was the reason for working in the way that I've described, and the way in which the team works."

Dr. Tony Brown, Consultant Clinical Psychologist