CHAPTER 4
Autistic Spectrum Disorders
Childhood autism, also known as ‘infantile autism’ or simply ‘autism’ is the
best known and best researched of a group of disorders that are variously
referred to asautistic spectrum disorders (ASDs)orpervasive developmental
disorders (PDDs). The other disorders in the group can be thought of as
milder variations on the same theme – meeting some but not all of the
diagnostic criteria for childhood autism. When people talk of an autistic
spectrum, they can mean a variety of things. In a narrow sense, they
can be referring simply to autism and related disorders, that is, a set
of conditions, all of which are significantly distressing or disabling for
the affected individual. In a broader sense, however, the spectrum can
refer to a dimension ranging from ‘classical’ autism at one extreme to
‘typically developing children’ at the other end – or perhaps extending
in the opposite direction to a group of children who have unusually
well-developed empathy, mind-reading skills and flexibility. In this broad
sense, everyone is somewhere on the autistic spectrum, just as everyone is
somewhere on the height spectrum. Having some of the features of autism
is not necessarily a disadvantage (unless society makes it so) and may have
advantages.
Epidemiology
As the recognition of ASDs has improved, the reported prevalence has
increased, with several recent good quality studies suggesting a rate of
around 1%. ‘Classical’ autism accounts for between 25% and 60% of
all ASDs. The male:female ratio is approximately 4:1. There is no clear
relation to socio-economic status; the links with high socio-economic
status reported by early studies were probably due to ascertainment bias.
Whereas autism was formerly viewed as an extremely rare condition
with a unique combination of the three characteristic features described
below, it is increasingly being realised that each of these features is itself a
spectrum, present to a greater or lesser extent. Some individuals have just
one or two of these features to a marked degree. Studies are underway to
Child and Adolescent Psychiatry, Third Edition. Robert Goodman and Stephen Scott.
©c2012 Robert Goodman and Stephen Scott. Published 2012 by John Wiley & Sons, Ltd.
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