What Is Pervasive Developmental Disorder -- Not Otherwise Specified (PDD-NOS)?

Question: What is pervasive developmental disorder -- not otherwise specified (PDD-NOS)?

Answer: Pervasive developmental disorder -- not otherwise specified, or PDD-NOS, is one of the five autism spectrum or pervasive developmental disorders as listed in the diagnostic and statistical manual of mental disorders. This particular autism spectrum disorder is considered to be among the least severe of the autism spectrum disorders.