Pervasive Developmental Disorders (PDDs) consists of five different disorders. This article has a brief overview of each Pervasive Developmental Disorder and what signs and symptoms to look for. Learn more about Rett Syndrome, Autistic Disorder, Asperger's Syndrome, and more.

The collection of five disorders known as the Pervasive Developmental Disorders (PDDs) are all characterized by delays in the development of communication and socialization skills. The symptoms or signs that often provide the first hints that a child may have a PDD include problems with using and understanding language, a lack of development of social relationships with both people and objects, notable discomfort with schedule changes, and repetitive body movements or behaviors.

The effects of the PDDs can be diminished by early intervention, but these disorders cannot be cured, which is why they are referred to as pervasive. The PDDs are usually evident by age three, although symptoms are sometimes noticeable in infancy.

The Pervasive Developmental Disorders are conceived of as having three categories, two of which are single disorders and one of which has three subsets of its own. Childhood Disintegrative Disorder (CDD; also called Heller's Syndrome), Rett Syndrome (also called Rett's Disorder), and Autism Spectrum Disorders (ASD) are the three categories of PDD, and Autism Spectrum Disorders is the one that has further subcategories. The three types of Autism Spectrum Disorder are Autistic Disorder, Asperger('s) Syndrome, and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS).

Childhood Disintegrative Disorder or Heller's Syndrome is manifested when a child who has previously exhibited normal development from age 2 to age 10 begins to regress in one or more areas  (this is the exception to the usual manifestation of PDDs in the first three years of life). The areas in which this regression occurs includes language capabilities, motor skills, and social interactions.

Rett Syndrome or Rett's Disorder only affects girls, who seem to develop normally until about six to eight months of age. At that point, the effects or Rett Syndrome on the gray matter of the brain begins to lead to behaviors that are sometimes characterized as "autistic," but also often includes the onset of seizures, dementia, and a loss of the use of the hands. The scientific name for this disorder is cerebroatrophic hyperammonemia.

Autistic Disorder—sometimes called Kanner's Syndrome, Infantile Autism, or Autism—affects boys three to four times as often as girls. It usually manifests by the time a child is three and affections communication, social skills, imaginative play, and the range of behaviors and interests that a child has. An autistic child may also have seizures, behavioral issues, and/or cognitive impairment.

Asperger's Syndrome is similar to Autistic Disorder in that a person who has it will have impaired social interactions and a limited range of behaviors and interests, but different from Autistic Disorder in that those with Asperger Syndrome do not also have cognitive and language impairments. Sometimes, in fact, people with Asperger's Syndrome may have above-average intelligence.

Pervasive Developmental Disorder Not Otherwise Specified  is also called Atypical Personality Development, Atypical Autism, or Atypical PDD.These names are used when some, but not all, features of one of the other PDDs are found.

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