Abstract
The pervasive developmental disorders are a group of neurodevelopmental disorders that include autistic disorder, Asperger's disorder, pervasive developmental disorder - not otherwise specified (PDD-NOS), childhood disintegrative disorder (CDD), and Rett's disorder. All feature childhood onset with a constellation of symptoms spanning social interaction and communication and including atypical behavior patterns. The first three disorders (autistic disorder, Asperger's disorder, and PDD-NOS) are currently referred to as autism spectrum disorders, reflecting divergent phenotypic and etiological characteristics compared to Rett's disorder and CDD. This chapter reviews research and clinical information to appropriate medical diagnosis and treatment.