Diagnosis of autism spectrum disorder

Accurate early diagnosis of autism spectrum disorder (ASD) is important because early intervention can significantly improve outcomes. A functional assessment may facilitate access to the National Disability Insurance Scheme (NDIS) for funded early intervention in children under 7 years (see also Early childhood intervention services), and is useful to guide management in older children, young people and adults. Confirmation of formal diagnosis of autism spectrum disorder may be needed in children over 7 years to access funded supports.

To facilitate diagnosis in a person with suspected autism spectrum disorder:

  • be alert for ‘red flags’—see ‘Red flags’ for autism spectrum disorder in children and adults
  • perform a medical evaluation to exclude medical causes for the presenting problems (eg hearing impairment); see Initial assessment in general practice
  • refer the person to a health professional with expertise in the assessment of behavioural and neurodevelopmental conditions for more detailed health and medical assessments—in children, this may be a paediatrician; in adults this may be a psychiatrist or psychologist
  • support the individual, their family and carers through the diagnostic process.

There is no biological diagnostic test for autism spectrum disorder; however, the disorder can be associated with a number of genetic and developmental conditions that should be screened for by the specialist. Autism spectrum disorder is diagnosed by trained health professionals, who observe an individual for specific behaviours relating to social communication and restricted or repetitive behaviours and interests. The health professionals commonly involved in autism spectrum disorder diagnostic assessment are listed in Health professionals commonly involved in autism diagnostic assessment.

The National guideline for the assessment and diagnosis of autism spectrum disorders in Australia (see [URL]) recommends that assessment should include both a comprehensive needs assessment and diagnostic evaluation.

Figure 1. Health professionals commonly involved in autism diagnostic assessment

general practitioner—medical examination to exclude medical causes for the presenting problems (eg hearing impairment)

developmental paediatrician—comprehensive medical and developmental assessment, including consideration of physical investigations

child or adult psychiatrist—diagnostic assessment, including consideration of psychiatric differential diagnosis (especially in adulthood), and psychiatric comorbidity

speech and language therapist—standardised assessment, including pragmatic language assessment

psychologist—autism diagnostic assessment (eg Autism Diagnostic Observation Schedule [ADOS], Autism Diagnostic Interview–Revised [ADI-R], cognitive testing, sensory profile)

occupational therapist—sensory assessment, working memory assessment, functional assessment

neurologist—medical assessment, especially if possible epilepsy

physiotherapist—gait assessment

social worker—family assessment