There is no clear medical test to diagnose ASD. Diagnosis is limited as an assessment process because it relies on a child demonstrating a set of specific, observable behavioural symptoms, along with parental report and developmental history. The diagnostic criteria are determined by the Diagnostic & Statistical Manual of Mental Disorders (DSM), which is an authoritative handbook used by Allied Health and medical practitioners nationally and internationally in the diagnosis of mental health and neurodevelopmental conditions.
The current iteration(DSM-V) was released in 2013, and changed the way autism was conceptualised. Before then, autism was not ‘officially’ considered a spectrum but rather, several independent diagnoses, specifically: Autistic Disorder, Asperger’s Disorder, Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS), Childhood Disintegrative Disorder(CDD), or Rett Syndrome. With the release of the DSM-V, ‘Autism Spectrum Disorder’ became a single diagnosis encompassing everyone who would have previously received a diagnosis of any of the aforementioned independent diagnoses.
As mentioned earlier the broad areas of difficulty in ASD were re-conceptualised from three into two: difficulties and deficits in social-communication skills, and the presence of sensory, restrictive, and repetitive behaviours and interests. In addition, rather than individual diagnostic categories, the DSM-V describes three ‘functional levels’ of ASD. These levels describe the amount of support an individual requires to function in the general community and allow a diagnosis of ASD to capture the variability across the spectrum. Importantly, an individual, can function at different levels between the two broad areas of difficulty. The levels of ASD as outlined in the DSM-5 8 are as follows:
Level 3: Requiring Very Substantial Support
Severe deficits in verbal and nonverbal social communication skills causing severe impairments in functioning, very limited initiation of social interactions, and minimal response to social overtures from others. Inflexibility of behaviour, extreme difficulty coping with change, or other restricted/repetitive behaviours. Great distress/ difficulty changing focus or action.
Level 2: Requiring Substantial Support
Marked deficits in verbal and nonverbal social communication skills; social impairments apparent even with supports in place; limited initiation of social interactions; and reduced or abnormal responses to social overtures from others. Inflexibility of behaviour, difficulty coping with change, or other restricted or repetitive behaviours appear frequently enough to be obvious to the casual observer and interfere with functioning in a variety of contexts. Distress and/or difficulty changing focus or action.
Level 1: Requiring Support
Without supports in place, deficits in social communication cause noticeable impairments. Difficulty initiating social interactions and clear examples of a typical or unsuccessful responses to social overtures of others. There may appear to have decreased interest in social interactions. Inflexibility of behaviour causes significant interference with functioning in one or more contexts. Difficulty switching between activities. Problems of organisation and planning hamper independence.