Autism spectrum disorder

Mary Hardimon · Published 20 May 2018 · Updated 2 November 2026

Clinical

Since being first described by Dr. Leo Kanner of John Hopkins University in 1943, the terminology used in the diagnosis and reference to autism spectrum disorder has changed multiple times, making it confusing for families and clinicians.

Autism or autism spectrum disorder?

Kanner described eleven children in his article Autistic Disturbances of Affective Contact who displayed “a need for sameness” and lacked social instinct to interact with others. He coined the disorder infantile autism, borrowing the term from Eugene Bleuler, who had used the term autism about adult patients with schizophrenia (although he did not suggest that these disorders were aetiologically related).

Subsequently, in 1944, Hans Asperger (psychologist) published an article, Die Autistischen Psychopathen im Kindesalter (Autistic Psychopathy in Childhood). Some argue that Hans was therefore rewarded with an eponymous disorder (which some countries have since removed). In 1926, a Russian neurological assistant (Eva Sucharewa) wrote a paper on the Schizoid Personality of Childhood, thought to describe Asperger’s Disorder.

Since its original description and subsequent registration with the International Classification of Diseases and the Diseases and Statistical Manual, autism spectrum disorder has encompassed many names, including but not limited to:

Which one is correct?

This is dependent on whether the ICD (International Classification of Diseases) or DSM (Diagnostic and Statistical Manual) is used, with the majority favouring DSM due to it being regularly revised and including diagnostic criteria (as well as being the nomenclature used by other government services such as Centrelink!)

You have been referred Charlie, a 2yo boy, by his general practitioner, who suspects that he has autism.

He attends your room with his mother, who feels helpless surrounding this potential “label” being considered for her son. She has a list of questions. However, her first one is, “why is this happening to me?” 

How common is autism?

https://the-riotact.com/increasing-numbers-of-canberra-residents-diagnosed-with-autism/199989

Sibling rate: 3–20%; the risk doesn’t vary by the gender of the affected child or their sibling. There is, however, difficulty in truly commenting on the sibling risk currently, as studies were at the time when Aspergers were generally included (MZ twin rate 36 – 96%)

Most common associated genetic disorders:

Other chromosomal “hotspots” include chromosomes 1, 2, 3q, 5p, 7q, 11q, 12q, 13q, 16p, 17, 18q, 21p, 22q, and X.

There is contention surrounding the very significant increase in the number of persons with autism spectrum disorder and whether this represents a true increase which has occurred through either increased overall incidence or increased recognition of the disorder, or whether this represents over-diagnosis. Because there is no sensitive and specific diagnostic test, this is difficult to determine.

Symptoms are typically noted at 12–24 months but may be noted earlier when there are associated severe developmental delays; delayed diagnosis may occur when the child can learn and compensate for their deficits.

What causes autism?

The aetiology and pathogenesis remain unclear, although multiple theories exist. It should be emphasised that immunisation has no association with autism spectrum disorder.­ A good fact sheet for families with this question in particular can be found at:

Pathophysiology

Autism is multifactorial, and despite advances over the last 75 years, exact pathogenesis is not determined and may indeed vary amongst children. Whilst genetic associations have been found, these are not sufficient alone and likely require an interplay of environmental stressors/triggers in order to result in the clinical condition of autism.

Suggested genetic, environmental and biological mechanisms in the development of autism

Four main accepted aetiological mechanisms (outside of genetics) include:

  1. Oxidative stress
  2. Environmental toxicants
  3. Mitochondrial dysfunction
  4. Immunology/Inflammation

It is okay to admit to our patients/families that we don’t have all the answers and don’t know the exact mechanisms surrounding aetiology/pathophysiology! 

Charlie sits in the corner of your room and refuses to look at or speak to you. He has no interest in you or your room. Mum wants to know…is he just naughty, or is this autism? 

What are the DSM diagnostic criteria for autism?

1. Persistent deficits in social communication and social interaction across multiple contexts, as manifested by the following, currently or by history (examples are illustrative, not exhaustive; see text):

2. Restricted, repetitive patterns of behaviour, interests, or activities, as manifested by at least two of the following, currently or by history:

3. Symptoms must be present in the early developmental period (but may not become fully manifest until social demands exceed limited capacities or may be masked by learned strategies in later life).

4. Symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning.

5. These disturbances are not better explained by intellectual disability (intellectual developmental disorder) or global developmental delay. Intellectual disability and autism spectrum disorder frequently co-occur; to make comorbid diagnoses of autism spectrum disorder and intellectual disability, social communication should be below that expected for the general developmental level.

If a diagnosis is established, it is important – from a prognostication and funding point of view – to determine the severity of the diagnosis, which is assessed based on social/communication and behaviours separately.

Severity of autism spectrum disorder

Specify if:

What are some red flags?

How do we make the diagnosis of autism?

Each state in Australia has different legislation on who can make a diagnosis, be it a general paediatrician, a developmental paediatrician, a child psychiatrist or a multidisciplinary panel. Regardless, unless the child has severe level 3 autism, the diagnosis should not be made in a one-off visit. It should involve input not only from the medical assessment but also from the family and the child’s school/childcare environment. Consider other mimics that may produce an autism-like picture.

They may benefit from different supports for the family, e.g., a history of trauma/attachment disorder that may result in poor eye contact similar to an autism diagnosis. The “Coventry Grid” can be useful for helping clinicians to recognise some of the subtle differences. 

Diagnosis should include the following:

Tools that may be useful include:

The most useful test is a thorough history with the caregiver and their childcare/school provider. When unsure regarding diagnosis, referral to specifically trained personnel is encouraged due to the inherent stigma associated with the lifelong diagnosis of autism.

After meeting with Charlie and his family multiple times and getting further history from his daycare, you determine that Charlie does indeed have autism. You remember that early intervention programs have been shown to improve overall outcomes but aren’t sure where to start.

What tests do we need to do?

Autism is a clinical diagnosis; medical investigations may help identify causal conditions or known complications/associations.

Audiological and vision evaluation

Genetics: Microarray + Fragile X

Baseline bloods:

EEG, MRI and metabolic studies are not recommended routinely, although they can be considered in subset populations. These tests have low therapeutic yield.

Treatment

Two features of therapy are of utmost importance:

  1. Multidisciplinary (speech, occupational therapy +/- psychology)
  2. Early and timely interventions

Therapy supports the child best when it is available in multiple environments (home and school).

But what can I do as a doctor?

Nationwide, Australia is transitioning to the National Disability Insurance Scheme, which requires both the family and medical professionals to advocate for the young person to ensure a financial package that will support the child in all domains that are affected, including but not limited to:

Other financial supports that the family may be eligible for include:

Parents should be encouraged to notify the school to coordinate services in this environment and, where appropriate, develop an individualised education plan.

What about medication?

Medication itself will not “treat” autism; however, it may be used for the associated diagnoses or difficulties seen. “Common” medications that may be seen being used by children with autism include:

Medication is not required for all children and should be considered on a case-by-case basis.

Surveillance

Primary care providers should provide surveillance for:

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