Specifying PDD-NOS: a comparison of PDD-NOS, Asperger syndrome, and autism.

Objective: To describe the clinical characteristics of children given a diagnosis of pervasive developmental disorder-not otherwise specified (PDD-NOS) by expert clinicians and to compare these to the clinical characteristics of children given a diagnosis of autism and Asperger syndrome (AS).

Method: Two hundred sixteen children with autism, 33 with AS, and 21 with PDD-NOS were compared on measures of level of functioning (communication, daily living and social skills, IQ, and age of acquisition of language) and on various symptoms of autism (impaired communication and reciprocal social interaction and a preference for repetitive and stereotyped activities).

Results: In terms of level of functioning measures, the PDD-NOS children had scores that were between those of the children with autism and those of the children with AS.