ICD-11

Autism spectrum disorder is characterised by persistent deficits in the ability to initiate and to sustain reciprocal social interaction and social communication, and by a range of restricted, repetitive, and inflexible patterns of behaviour, interests or activities that are clearly atypical or excessive for the individual’s age and sociocultural context. The onset of the disorder occurs during the developmental period, typically in early childhood, but symptoms may not become fully manifest until later, when social demands exceed limited capacities. Deficits are sufficiently severe to cause impairment in personal, family, social, educational, occupational or other important areas of functioning and are usually a pervasive feature of the individual’s functioning observable in all settings, although they may vary according to social, educational, or other context. Individuals along the spectrum exhibit a full range of intellectual functioning and language abilities.

All definitional requirements for both autism spectrum disorder and disorder of intellectual development are met and there is marked impairment in functional language (spoken or signed) relative to the individual’s age, with the individual not able to use more than single words or simple phrases for instrumental purposes, such as to express personal needs and desires.

All definitional requirements for both autism spectrum disorder and disorder of intellectual development are met and there is marked impairment in or complete absence of ability relative to the individual’s age to use functional language for instrumental purposes (e.g., to express personal needs and desires). The co-occurring Disorder of intellectual development should be classified separately, using the appropriate category to designate severity (i.e., mild, moderate, severe, profound, provisional). Because autism spectrum disorder inherently involves social deficits, assessment of a co-occurring Disorder of intellectual development should place greater emphasis on intellectual, conceptual, and practical domains than on social adaptation