3 Mapping the autistic spectrum
3.1 History of the spectrum concept
Many individuals have autistic-like symptoms that do not meet the requisite number or profile of features for a diagnosis of classic autism. In Section 3 we will consider the background to the spectrum concept and some different interpretations of the variations that it includes. The section concludes by setting these ideas in a developmental context: different patterns of symptoms in infancy may result in qualitatively different outcomes for individuals later.
An intriguing fact in the history of autism research is that while Kanner's work in America led him to introduce ‘early infantile autism’ as a clinical entity in 1943, another doctor, Hans Asperger, working at the same time in Vienna, described a very similar syndrome, which he called ‘autistic psychopathy’ (Asperger, 1944). Asperger described children with unusual or impoverished use of gesture, strangely formal or pedantic use of language, and difficult relations with their peers, parents and teachers. Quite often these children had been referred to Asperger because of their ‘anti-social’ or unfeeling behaviour towards others. But some of them were exceptionally able academically. Asperger worked with a number of his patients into adulthood. Here is an extract from one of his cases studies:
It was as if he never took any notice of other people. He behaved so absent-mindedly that he often did not recognise his closest acquaintances. He was extremely clumsy and gauche, and there were all the difficulties we described earlier in learning to deal with the practical chores of everyday life. He remained awkward and socially unconcerned with his demeanour … When he was at school there were constant serious difficulties … For languages he had no talent at all. In secondary school … he was able to get by only on the basis of his other abilities … Even as a toddler, one could see in him a most unusual and spontaneous mathematical talent. Through persistent questioning of adults he acquired all the necessary knowledge from which he then worked independently … Not long after the start of his university studies, reading theoretical astronomy, he proved a mathematical error in Newton's work … In an exceptionally short time he became an assistant professor at the Department of Astronomy …
(Asperger, 1944. Translated by Frith, 1991, pp. 88–9)
Not all of Asperger's patients fitted the pattern of milder social disability and outstanding intellectual talents represented by this case study. However, his observations indicated that autism might be a heterogeneous category, and this variability was further documented in 1979 by Lorna Wing and Judith Gould (see Box 3).
Box 3: The incidence of autistic spectrum disorders
Wing and Gould carried out an epidemiological study in which they screened 35,000 children under the age of 15 for the presence of one or more symptoms within the main autistic triad. Of all these children, 17 (or just under five children in 10,000) matched accepted criteria for ‘classic’ autism. However, a considerably larger group had some difficulties in reciprocal social interaction, usually coupled with communication problems and an impoverished range/scope of activities. Including this wider group, the overall estimate of prevalence was more like 21 children in 10,000 (equivalent to 0.2 per cent). Wing and Gould's conclusion – that the autistic syndrome embraces a core set of symptoms and variations on this core pattern – established the spectrum concept.
More recent studies have suggested even higher rates of incidence for the broad spectrum: between 0.6 and 1 per cent of all school-age children. A likely explanation is that diagnostic practices have changed since the Wing and Gould study to include more borderline cases. However, some researchers have recently argued that there is an increase in the actual incidence of autistic spectrum disorders, claiming that it is diagnoses of classic cases that have increased. The evidence for this claim is currently unclear.
Epidemiological study: Large-scale study of the incidence and distribution of a disorder within a population.