Atypical Autism

Atypical autism can be seen as the official, diagnostic equivalent of terms such as ‘Autistic Tendencies’ of ‘Autistic Traits’ and is another example of the importance of a concept of a spectrum of disorders. People who are diagnosed as having atypical autism are those who nearly meet the criteria but do not conform completely. Even among individuals who are diagnosed with autism according to the DSM or ICD criteria there is room for variation between more ‘classic’ forms of the condition and less overt examples42.

Atypical autism might apply to individuals who generally appear to have autism but who differ from the criteria in terms of age of onset or presentation of characteristics43. Where onset of autistic impairments and delays of development are in evidence only after 36 months but the ‘symptoms’ of autism are fulfilled a diagnosis of atypical autism might be used. This recognises both the possibility that autism might, in some rare cases, effect development after 36 months to a degree at which the child is effectively autistic, and that it may be hard to identify autism among come children under three years of age, especially if they have a severe or profound learning disability. Due to the heterogeneity of autism, and because of the complex neurological causes of autism it is possible that the condition could still be caused by specific selective damage after the age of 36 months, or that damage and impairments could be caused over a length of time and not be fully evident until after four months. The concept of atypical autism also allows for an official diagnosis for individuals who require appropriate interventions but who might not fulfil all the diagnostic criteria. Conversely there is a risk that a diagnosis be made where it is inappropriate. This is largely dependent on the competence of the person diagnosing.

Atypical autism might also refer to atypicallity of characteristics. This can apply where there is evidence of impairments in all the three areas of autism (impairments in social interaction, in language and communication, and in stereotyped and repetitive behaviours and interests), but where examples of such impairment does not meet the required number for diagnosis (six symptoms out of a possible twelve, with at least two from the social interaction criteria, and one each from the other two areas). Like autism, atypical autism must be differentiated from other similar conditions such as Rett’s Syndrome and Heller’s Syndrome. In practice atypical autism should be considered in the same way as autism and Asperger’s syndrome with specific recognition for common characteristics of autism which might not be so impaired. Both atypical autism and Asperger’s syndrome are conditions which should be treated as central to the autistic spectrum and not peripherally.