Autism Spectrum Disorder (ASD): Condition Information

What is ASD?

ASD is a complex neurological and developmental disorder that affects how a person acts and interacts with others, communicates, and learns. ASD affects the structure and function of the brain and nervous system. Because it affects development, ASD is called a developmental disorder. ASD can last throughout a person's life. People with this disorder have problems with:

• Communication
• Interactions with other people (social skills)
• Restricted interests and repetitive behaviors

Autism Is a Spectrum Disorder

Different people with autism can have different symptoms. For this reason, autism is known as a spectrum disorder - a group of disorders with a range of similar features. ^1,2,3,4

What conditions are included in the ASD category?

ASD includes: ^5,6,7,8,9

• Autistic disorder ("classic" autism). Autistic disorder is often what people think of when they think of autism.
• Asperger syndrome. This ASD usually involves milder symptoms, mostly related to social behaviors.
• Pervasive developmental disorder not otherwise specified (PDD-NOS, or "atypical" autism). PDD-NOS includes some, but not all, of the features of classic autism and/or Asperger syndrome.

This website uses "ASD" and "autism" to mean the same thing.

In some cases, health care providers use a broader term-pervasive developmental disorders (PDD)-to describe autism. The PDD category includes the ASDs mentioned above. It also includes childhood disintegrative disorder and Rett syndrome, two conditions in which a child develops normally for several months or years, then loses skills related to language, movement and coordination, and other brain functions.

Depending on his or her specific symptoms, a person with autism may fall into the ASD or the PDD category. Sometimes the terms "ASD" and "PDD" are used to mean the same thing because both categories include "classic" autism.

1. Diagnostic and Statistics Manual, 4th Edition. (1994). American Psychiatric Association: Washington, DC. [top]
2. Diagnostic and Statistics Manual, 4th Edition Text Revision. (2000). American Psychiatric Association: Washington, DC. [top]
3. Filipek, P. A., Accardo, P. J., Ashwal, S., Baranek, G. T., Cook, E. H. Jr., Dawson, G., et al. (2000). Practice parameter: Screening and diagnosis of autism-Report of the Quality Standards Subcommittee of the American Academy of Neurology and the Child Neurology Society. Neurology, 55, 468-479. [top]
4. Johnson, C. P., & Myers, S. M.; American Academy of Pediatrics Council on Children with Disabilities. (2007). Identification and evaluation of children with autism spectrum disorders. Pediatrics, 120(5), 1183-1215. [top]
5. Diagnostic and Statistics Manual, 4th Edition. (1994). American Psychiatric Association: Washington, DC. [top]
6. Diagnostic and Statistics Manual, 4th Edition Text Revision. (2000). American Psychiatric Association: Washington, DC. [top]
7. Filipek, P. A., Accardo, P. J., Ashwal, S., Baranek, G. T., Cook, E. H. Jr., Dawson, G., et al (2000). Practice parameter: Screening and diagnosis of autism-Report of the Quality Standards Subcommittee of the American Academy of Neurology and the Child Neurology Society. Neurology, 55, 468-479. [top]
8. Johnson, C. P., & Myers, S. M.; American Academy of Pediatrics Council on Children with Disabilities. (2007). Identification and evaluation of children with autism spectrum disorders. Pediatrics, 120(5), 1183-1215. [top]
9. Diagnostic and Statistical Manuel of Mental Disorders, 5th edition. (2013). American Psychiatric Association: Washington, DC. [top]