autism spectrum disorder

autism spectrum disorder (ASD), any of a group of neurobiological disorders that are characterized by deficits in social interaction and communication and by atypical behaviors, interests, and activities.

In 1911 Swiss psychiatrist Eugen Bleuler coined the term autism (from the Greek autos, meaning “self”), using it to describe the withdrawal into the self that he observed in patients affected by schizophrenic disorders. However, in 1943 Austrian-born American psychiatrist Leo Kanner recognized autism as a disorder distinct from schizophrenia and gave autism its modern description. In subsequent decades, several autism-like disorders also were identified, resulting in the group of conditions known as autism spectrum disorders, or ASDs.

In the Diagnostic and Statistical Manual of Mental Disorders-IV (1994; DSM-IV), ASDs included distinct neurobiological disorders, such as autism (or classic autism), Asperger syndrome, Rett syndrome, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified (PDD-NOS). All five of these disorders were historically included under the broad classification of pervasive developmental disorders (PDDs), a group of conditions characterized by early-childhood onset and impairment of language acquisition, communication, social behavior, and motor function. With the release of DSM-5 (2013), however, the PDD grouping was disbanded, and conditions previously considered to be PDDs were reclassified as ASDs.