October 01, 2022
Autism and Pervasive Developmental Disorder

October  2011
What is Autism / PDD?

Autism/Pervasive Developmental Disorder (PDD) is a neurological disorder that affects a child’s ability to communicate, understand language, play, and relate to others. PDD represents a distinct category of developmental disabilities that share many of the same characteristics.

The different diagnostic terms that fall within the broad meaning of PDD, include:

  • Autistic Disorder,
  • Asperger’s Disorder,
  • Rett’s Disorder,
  • Childhood Disintegrative Disorder, and
  • Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS).
    While there are subtle differences and degrees of severity among these conditions, treatment and educational needs can be very similar for all of them.

In the diagnostic manual used to classify mental disorders, the DSM-IV-TR (American Psychiatric Association, 2000), “Autistic Disorder” is listed under the heading of “Pervasive Developmental Disorders.” A diagnosis of autistic disorder is made when an individual displays 6 or more of 12 symptoms across three major areas: (a) social interaction, (b) communication, and (c) behavior. When children display similar behaviors but do not meet the specific criteria for autistic disorder (or the other disorders listed above), they may receive a diagnosis of Pervasive Developmental Disorder Not Otherwise Specified, or PDD-NOS.

Autism is one of the disabilities specifically defined in the Individuals with Disabilities Education Act (IDEA), the federal legislation under which infants, toddlers, children, and youth with disabilities receive early intervention, special education and related services. IDEA defines the disorder as “a developmental disability significantly affecting verbal and nonverbal communication and social interaction, generally evident before age 3, that adversely affects a child’s educational performance. Other characteristics often associated with autism are engagement in repetitive activities and stereotyped movements, resistance to environmental change or change in daily routines, and unusual responses to sensory experiences.

How Common is Autism / PDD?

Information from the National Institute of Mental Health and the Center for Disease Control and Prevention (CDC) indicates that between 2 to 6 per 1,000 children (from 1 in 500 to 1 in 150) have some form of autism/PDD. These disorders are four times more common in boys than in girls, although Rett’s Disorder has only been reported and diagnosed in girls.

The causes of autism or PDD are unknown. Currently, researchers are investigating areas such as brain development, structure, genetic factors and biochemical imbalance in the brain as possible causes. These disorders are not caused by psychological factors.

What are the Signs of Autism / PDD?
Some or all of the following characteristics may be observed in mild to severe forms:
  • Communication problems (e.g., using and understanding language);
  • Difficulty relating to people, objects, and events;
  • Unusual play with toys and other objects;
  • Difficulty with changes in routine or familiar surroundings; and
  • Repetitive body movements or behavior patterns.
Children with autism or PDD vary widely in abilities, intelligence, and behaviors. Some children do not speak; others have language that often includes repeated phrases or conversations. Children with more advanced language skills tend to use a small range of topics and have difficulty with abstract concepts. Repetitive play skills, a limited range of interests, and impaired social skills are generally evident as well. Unusual responses to sensory information —for example, loud noises, lights, certain textures of food


Richman, S. (2000). Raising a child with autism: A guide to applied behavior analysis for parents. London: Jessica Kingsley Publishers. (www.jkp.com/ )

Tsai, L.Y. (1998). Pervasive developmental disorders. Washington, DC: NICHCY. (Available online at: www.nichcy.org/pubs/factshe/fs20txt.htm )

Wiseman, N.D. (2006). Could it be autism? New York: Broadway Books. (http://www.broadwaybooks.com/ )

For more information, books, and videos on autism spectrum disorders, the Autism Society of North Carolina Bookstore has over 400 titles in their collection. (919-743-0204; http://www.autismbookstore.com/ )

or fabrics—are also common.

Beytien, A. (2004). Family to family: A guide to living life when a child is diagnosed with an autism spectrum disorder [Video]. Higganum, CT: Starfish Specialty Press. (877-782-7347; http://www.starfishpress.com/ )

DuCharme, R., & Gullotta, T.P. (Eds.) (2004). Asperger syndrome: A guide for professionals and families. New York: Springer Publishers. (800-777-4643; http://www.springeronline.com/ )

O’Brien, M., & Daggett, J.A. (2006). Beyond the autism diagnosis: A professional’s guide to helping families. Baltimore, MD: Brookes Publishing (800-638-3775; http://www.brookespublishing.com/ )