• Parents often tell us their child has received several diagnoses in the pervasive developmental disorder spectrum. The differences between these diagnoses hinge on subtle differences in language development, degree of severity of symptoms, and age of onset as well as other clinical features. For instance, the diagnosis of Asperger disorder may be considered for children who show many of the features of autistic disorder, but do not have a history of language delay. PDD/NOS is a diagnosis often considered for children who show some signs of autistic disorder, but who do not meet the specific diagnostic criteria for the other PDDs. There is no medical "test" that can be used to diagnose PDDs.

  There are other terms that are used by parents, health care providers and researchers, but currently these are not "official" diagnostic terms. These terms include atypical autistic disorder, high-functioning autistic disorder, and autistic disorder spectrum condition.

  Because autistic disorder is a spectrum of disorders, and because differences between diagnoses may be subtle, clinicians sometimes disagree over which PDD diagnosis is most appropriate for an individual. As a result, some individuals receive multiple PDD diagnoses.

Asperger Disorder
Individuals with Asperger disorder do not have a delay in spoken language development, but can have serious deficits in social and communication skills.

Pervasive Developmental Disorder Not Otherwise Specified (PDD/NOS)
Is a diagnosis often considered for children who show some signs of autistic disorder, but who do not meet the specific diagnostic criteria for the other PDDs.

Rett Disorder
Rett disorder is among the most common genetic cause of profound intellectual and physical disability in girls, occurring more commonly than 1 in 10,000 female births.

Childhood Disintegrative Disorder
Children with childhood disintegrative disorder develop normally for a relatively prolonged period before developing a condition that resembles autistic disorder.