2.1 Definitions and diagnosis
There is now
'a high degree of consensus on the diagnostic criteria for autism and consistency in the evidence on the validation of autism as a diagnostic category.'
(Rutter, 1996, p. 257).
Kanner (1943) first identified a condition in eleven cases that he felt had sufficient in common, and were sufficiently different from other conditions, to merit a separate syndrome.
He referred to this disorder as a disorder of affective contact and identified criteria in terms of interpersonal development, communication and imagination deficits that have largely stood the test of time. Wing and Gould (1979) established the fact that the condition often cooccurred with learning difficulties. The two major diagnostic systems now have common criteria for a diagnosis of autism based on a triad of impairments in social interaction, communication and a lack of flexibility in thinking and behaviour (DSM IV: American
Psychiatric Association, 1994; ICD 10: World Health Organisation, 1992). This same triad of impairments underpins other autistic like conditions said to form 'autistic spectrum disorders'
(Wing, 1996) or 'pervasive developmental disorders'. The spectrum may contain a number of different medical conditions with different diagnostic criteria, but sharing those common developmental difficulties.
2.2 Asperger syndrome
Asperger, in 1944, first wrote about children having characteristics similar to those identified by Kanner, but with at least average levels of intellectual ability and good structural language skills; these individuals are now said to have Asperger syndrome. Some have maintained that
Asperger syndrome is a distinct syndrome (Trevarthen, Aitken, Papoudi and Robarts, 1996) 15 and this is supported by current diagnostic formulations (DSM-IV: APA, 1994; ICD-10:
WHO, 1992). When reviewing