Pervasive Developmental Disorder - Classification

Classification

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.