Classic autism

Classic autism—also known as childhood autism, autistic disorder, or Kanner's syndrome—is a formerly diagnosed neurodevelopmental disorder first described by Leo Kanner in 1943. It is characterized by atypical and impaired development in social interaction and communication as well as restricted and repetitive behaviors, activities, and interests. These symptoms first appear in early childhood and persist throughout life.

Classic autism was last recognized as a diagnosis in the DSM-IV and ICD-10, and has been superseded by autism-spectrum disorder in the DSM-5 (2013) and ICD-11 (2022). Globally, classic autism was estimated to affect 24.8 million people as of 2015.

Autism is likely caused by a combination of genetic and environmental factors, with genetic factors thought to heavily predominate. Certain proposed environmental causes of autism have been met with controversy, such as the fraudulent vaccine hypothesis that, although disproved, has negatively impacted vaccination rates among children.

Since the DSM-5/ICD-11, the term "autism" more commonly refers to the broader autism spectrum.