Autism spectrum disorders are diagnosed on the basis of criteria set out in manuals and the research literature. The main sources of diagnostic criteria are the Diagnostic and Statistical Manual of Mental Disorders, currently in a revised fourth edition and commonly known as the DSM-IV (pronounced "D S M 4"), and the International Classification of Diseases and Health Related Problems, in its tenth revision and commonly known as the ICD-10 (pronounced "I C D 10"). Versions of the DSM are produced by the American Psychiatric Association, while the ICD is published by the World Health Organisation. It is more common for clinicians in Australia to use DSM-IV criteria when assessing children for ASD, but this is not universally the case.
The DSM-IV includes a diagnostic category of "Autistic Disorder" in the section titled Pervasive Developmental Disorders. The diagnostic criteria for the DSM-IV and the ICD-10 for autism are almost identical, although in the ICD-10 it is known as "Childhood Autism". For a diagnosis of autism, at least two symptoms of impairment in social interaction, one symptom of impairment in communication, and one symptom of restricted and repetitive behaviour must be present.
The DSM-IV includes a diagnostic category of "Asperger's Disorder" in the section titled Pervasive Developmental Disorders. The diagnostic criteria for the DSM-IV and the ICD-10 for this condition are almost identical, although in the ICD-10 it is known as "Asperger's Syndrome". It is common in both the research literature and in clinical settings for the condition to be referred to as "Asperger syndrome", as well as the previous names. For a DSM-IV diagnosis of Asperger's Disorder, at least two symptoms of impairment in social interaction and one symptom of restricted and repetitive behaviour must be present. In addition, there must be no significant general delay in development of language, normal cognitive development, age-appropriate self-help skills, adaptive behaviour, and curiosity about the environment. There is a lot of debate as to whether Asperger syndrome should be a separate diagnostic category to autism, and this is discussed further below.
The DSM-IV includes a diagnostic category of "Pervasive Developmental Disorder Not Otherwise Specified (Including Atypical Autism)" in the section titled Pervasive Developmental Disorders. This diagnosis is used where there is a sever and pervasive impairment in one or more categories of the symptoms of autism, but where there are cases of late onset after 3 years of age, one or more diagnostic criteria are not met for Autistic Disorder or Asperger's Disorder, or symptoms are present but not severe enough for a diagnosis of another ASD.
Dr Larry Cashion for A4