what is asd disorder
Autism, Autistic Spectrum Disorders (ASD) and Pervasive Developmental Disorders (PDD) What are the autistic spectrum disorders (ASD)? Autism spectrum disorders, or ASD, are also called pervasive developmental disorders (PDD) because they involve delay in many areas of development. PDD or ASD is a category that includes five different disorders of development, each with differing severities and patterns: Autistic Disorder.