ICD
The World Health Organizations International Classification of Diseases (11th Revision) ICD-11, regarded as the global standard, was released in June 2018 and came into full effect as of January 2022. It describes ASD as follows:
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 individuals 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 individuals 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. ICD-11 was produced by professionals from 55 countries out of the 90 countries involved and is the most widely used reference worldwide. Clinicians use the ICD as a reference for diagnosis and reporting but researchers, particularly in the US, continue to use the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR from 2022, DSM-5 from 2013, or their predecessors) as some material is not included in the ICD (the ICD is broader in scope, covering general as well as mental health).
The autism spectrum is a range of neurodevelopmental conditions generally characterized by difficulties in social interactions and communication, repetitive behaviors, intense interests, and unusual responses to sensory stimuli. It is commonly referred to as autism or, in the context of a professional diagnosis, autism spectrum disorder (ASD), but the latter term remains controversial among neurodiversity advocates, neurodiversity researchers, and many autistic people due to the use of the word disorder and due to questions about its utility outside of diagnostic contexts.A spectrum disorder is one that can manifest very differently from person to person: any given person with the disorder is likely to show some but not all of the characteristics associated with it, and may show them to very different degrees. Different autistic people might show strikingly different characteristics, and the same person might also present differently at different times. Historically, the autism spectrum was divided into sub-categories, but questions persisted over the validity of these divisions. The most recent editions of the major English-language diagnostic manuals, Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR, published in 2022) and International Classification of Diseases (ICD-11, released in 2021) both list ASD as a single disorder.Given concerns about the appropriateness of the term disorder, many sources prefer to use the word "autism" without any additional words, on the basis that this is the least controversial term among people with different perspectives or (in the United Kingdom) autism spectrum conditions (ASC) rather than ASD.