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.
The word autism first took its modern sense in German, when Asperger adopted Bleulers terminology autistic psychopaths in a 1938 lecture in German about child psychology. Asperger was investigating an ASD which was later known as Asperger syndrome, although it did not become widely recognized as a separate diagnosis until 1981. In English, Kanner first used autism in its modern sense when he introduced the label early infantile autism in a 1943 report of 11 children with striking behavioral similarities. Almost all the characteristics described in Kanners first paper on the subject, notably "autistic aloneness" and "insistence on sameness", are still regarded as typical of the autistic spectrum of disorders. It is not known whether Kanner derived the term independently of Asperger.Kanners reuse of autism led to decades of confused terminology like infantile schizophrenia, and child psychiatrys focus on maternal deprivation led to misconceptions of autism as an infants response to "refrigerator mothers". Starting in the late 1960s, autism was established as a separate syndrome. However, Kanner was the first person to describe ASD as a neurodevelopmental disorder in 1943 by calling it infantile autism and therefore rejected the refrigerator mother theory.The discussion of autism prior to the twentieth century is one that brings about much controversy. Without researchers being able to meet a consensus on the varying forms around the condition, there was a lack of research being conducted on the disorder. Discussing the syndrome and its complexity frustrated researchers. Controversies have surrounded various claims regarding the etiology of ASDs.