Although Bleuler [6] first coined the term autism, our understanding
of the disorder with its various subtypes comes from
the pioneering works of Kanner [7] and Asperger [8]. Today,
the DSM-IV-TR [9] provides the most widely used definition
of autism. It is based on twelve diagnostic criteria categorized
under three areas describing autism as a disorder of neural
development characterized by impaired social interaction and
communication, and by restricted and repetitive behavior.
Overt symptoms from the age of six months are manifested by
age two or three. These symptoms tend to continue through
adulthood, though often in a muted form. As said, autism
is distinguished not by a single symptom, but by a characteristic
triad of symptoms. Autism is also a highly variable
neurodevelopmental disorder first appearing during infancy
or childhood. Generally, it follows a steady course without
remission. The DSM-IV-TR has classified autism as one of the
five pervasive developmental disorders. The current diagnosis
of autism is based on the manifested behavior as described in
the DSM-IV-TR, not the cause or the mechanism.