a behavioral syndrome of neurological dysfunction characterized by impaired reciprocal social interactions, impaired verbal and nonverbal communication, impoverished or diminished imaginative activity, stereotypic movements, and a markedly restricted repertoire of activities and interests relative to age. In DSM-IV-TR, the disorder becomes evident by the age of 3 is designated autistic disorder when diagnosed, and is categorized as a pervasive developmental disorder. It is commonly associated with mental retardation, speech delay, and is apparent in 20 or so individuals of every 10,000. Also known as infantile autism, Kanner's syndrome.
AUTISTIC DISORDER: "A person diagnosed with autistic disorder exhibits social and cognitive deficits that are apparent by the age of 3. "