Asperger syndrome is one of the autism spectrum disorders (ASD) or pervasive developmental disorders (PDD), which are a spectrum of psychological conditions that are characterized by abnormalities of social interaction and communication that pervade the individual's functioning, and by restricted and repetitive interests and behavior. Like other psychological development disorders, ASD begins in infancy or childhood, has a steady course without remission or relapse, and has impairments that result from maturation-related changes in various systems of the brain.^[8] ASD, in turn, is a subset of the broader autism phenotype (BAP), which describes individuals who may not have ASD but do have autistic-like traits, such as social deficits.^[9] Of the other four ASD forms, autism is the most similar to AS in signs and likely causes but its diagnosis requires impaired communication and allows delay in cognitive development, Rett syndrome and childhood disintegrative disorder share several signs with autism but may have unrelated causes, and pervasive developmental disorder not otherwise specified (PDD-NOS) is diagnosed when the criteria for a more specific disorder are unmet.^[10] The extent of the overlap between AS and high-functioning autism (HFA—autism unaccompanied by mental retardation) is unclear.^[5][11][12] The current ASD classification may not reflect the true nature of the spectrum.^[13] A panel session at a 2008 diagnosis-related autism research planning conference noted problems with the classification of AS as a distinct subgroup of ASD, and two of three breakout groups recommended eliminating AS as a separate diagnosis.

from: http://en.wikipedia.org/wiki/Aspergers (3/17/09)