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Autism spectrum disorder: Terminology, epidemiology, and pathogenesis

Marilyn Augustyn, MD
Section Editors
Marc C Patterson, MD, FRACP
Carolyn Bridgemohan, MD
Deputy Editor
Mary M Torchia, MD


Autism spectrum disorder (ASD) is a biologically based neurodevelopmental disorder characterized by impairments in two major domains: 1) deficits in social communication and social interaction and 2) restricted repetitive patterns of behavior, interests, and activities [1]. ASD encompasses disorders previously known as autistic disorder (classic autism, sometimes called early infantile autism, childhood autism, or Kanner's autism), childhood disintegrative disorder, pervasive developmental disorder-not otherwise specified, and Asperger disorder (also known as Asperger syndrome). (See "Autism spectrum disorder: Diagnosis", section on 'Diagnostic criteria'.)

The terminology, epidemiology, and pathogenesis of ASD will be reviewed here. The impact of these changes is expected to evolve over several months to years as multiple systems of diagnosis and treatment are adjusted accordingly. Surveillance and screening, clinical features, diagnosis, and management of ASD are discussed separately. (See "Autism spectrum disorder: Surveillance and screening in primary care" and "Autism spectrum disorder: Clinical features" and "Autism spectrum disorder: Diagnosis" and "Autism spectrum disorder in children and adolescents: Overview of management".)


Overview — The terminology and diagnostic criteria for ASD varies geographically. The Diagnostic and Statistical Manual of Mental Disorders (DSM) is used predominantly in the United States, and was updated in 2013 (DSM-5) [1]. The World Health Organization International Classification of Diseases, 10th revision (ICD-10) is used in other countries throughout the world [2]. The 11th revision of the ICD is expected in 2017 [3].

Before the publication of DSM-5, the diagnostic criteria and categories were relatively similar between the two systems in clinical use, though the nomenclature of "ASD," which was widely used, was not officially in the DSM IV. However, with DSM-5, a single diagnosis, "autism spectrum disorder" has replaced previous subtypes (eg, Asperger syndrome, "pervasive developmental disorder-not otherwise specified") and the clinical heterogeneity is indicated with specifiers for severity and associated conditions (eg, intellectual impairment, language impairment) [1]. Specific changes in the DSM diagnostic criteria are discussed separately. (See "Autism spectrum disorder: Diagnosis", section on 'Diagnostic criteria'.)

The effects of the updated DSM-5 terminology on the epidemiology, identification, diagnosis, and management of ASD, as well as the day-to-day lives of individuals with ASD, have yet to be determined.

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Literature review current through: Sep 2017. | This topic last updated: Mar 07, 2017.
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