PDD

The diagnostic category pervasive developmental disorders (PDD), as opposed to specific developmental disorders (SDD), refers to a group of five disorders characterized by delays in the development of multiple basic functions including socialization and communication. The pervasive developmental disorders are:

• Pervasive developmental disorder not otherwise specified (PDD-NOS), which includes atypical autism, and is the most common;
• Autism, the best-known;
• Asperger syndrome;
• Rett syndrome; and
• Childhood disintegrative disorder (CDD).

The first three of these disorders are commonly called the autism spectrum disorders; the last two disorders are much rarer, and are sometimes placed in the autism spectrum and sometimes not.

Parents may note symptoms of PDD as early as infancy and typically onset is prior to three years of age. PDD itself does not affect life expectancy.

There is a division among doctors on the use of the term PDD. Many use the term PDD as a short way of saying PDD-NOS. Others use the general category label of PDD because they are hesitant to diagnose very young children with a specific type of PDD, such as autism. Both approaches contribute to confusion about the term, because the term PDD actually refers to a category of disorders and is not a diagnostic label.