A Canadian meta-analysis from 2019 confirmed these effects as the profiles of people diagnosed with autism became less and less different from the profiles of the general population. In the US, the rates for diagnosed ASD have been steadily increasing since 2000 when records began being kept. While it remains unclear whether this trend represents a true rise in incidence, it likely reflects changes in ASD diagnostic criteria, improved detection, and increased public awareness of autism. In 2012, the NHS estimated that the overall prevalence of autism among adults aged 18 years and over in the UK was 1.1%.A 2016 survey in the United States reported a rate of 25 per 1,000 children for ASD. It is important to note that rates of autism are poorly understood in many low- and middle-income countries, which affects the accuracy of global ASD prevalence estimates, but it is thought that most autistic individuals live in low- and middle-income countries.In the UK, from 1998 to 2018, the autism diagnoses increased by 787%. This increase is largely attributable to changes in diagnostic practices, referral patterns, availability of services, age at diagnosis, and public awareness (particularly among women), though unidentified environmental risk factors cannot be ruled out. The available evidence does not rule out the possibility that autisms true prevalence has increased; a real increase would suggest directing more attention and funding toward psychosocial factors and changing environmental factors instead of continuing to focus on genetics.
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.