Pervasive Development Disorders

Autism is classified as one of the pervasive developmental disorders. Researchers and therapists have developed several sets of diagnostic criteria for autism. Some frequently used criteria include:

• Absence or impairment of imaginative and social play
• Impaired ability to make friends with peers
• Impaired ability to initiate or sustain a conversation with others
• Stereotyped, repetitive, or unusual use of language
• Restricted patterns of interests that are abnormal in intensity or focus
• Apparently inflexible adherence to specific routines or rituals
• Preoccupation with parts of objects

Children with some symptoms of autism, but not enough to be diagnosed with the classical form of the disorder, are often diagnosed with pervasive developmental disorder–not otherwise specified (PDD–NOS).

People with autistic behavior but well-developed language skills are often diagnosed with Asperger syndrome. Children who appear normal in their first several years, then lose skills and begin showing autistic behavior, may be diagnosed with childhood disintegrative disorder (CDD). Girls with Rett syndrome, a sex-linked genetic disorder characterized by inadequate brain growth, seizures, and other neurological problems, also may show autistic behavior. PDD– NOS, Asperger syndrome, CDD, and Rett syndrome are referred to as autism spectrum disorders.

These disorders are all outlined in the Diagnostic and Statistical Manual DSM-IV (PDF) of the American Psychiatric Association.