PDD - Classification

Classification

The pervasive developmental disorders are:

• Pervasive developmental disorder not otherwise specified (PDD-NOS), which includes atypical autism, and is the most common (47% of diagnoses);
• Autism, the best-known;
• Asperger syndrome (9% of autism diagnoses);
• 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.

The release of DSM-5 in May 2013 is expected to remove PDD and be replaced with Autism Spectrum Disorders, and will not include all of the previously included disorders.