Autism spectrum

The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulties in social interaction, verbal and nonverbal communication, and the presence of repetitive behavior and restricted interests. Other common signs include unusual responses to sensory stimuli.

Autism is generally understood as a '' spectrum disorder'', which means that it can manifest differently in each person: any given autistic individual is likely to show some, but not all, of the characteristics associated with it, and the person may exhibit them to varying degrees. Some autistic people remain nonspeaking over the course of their lifespan, while others have relatively unimpaired spoken language. There is large variation in the level of support people require, and the same person may present differently at varying times. Historically, autism was divided into sub-categories, but there were persistent questions over the validity of these divisions, and the most recent editions of the main diagnostic manuals list ASD as a single disorder.

While psychiatry traditionally classifies autism as a neurodevelopmental disorder, many autistic people, most autistic advocates and a rapidly increasing number of researchers see autism as part of neurodiversity, the natural diversity in human thinking, and experience, with strengths, differences, and weaknesses. On this view, promoted by the autism rights movement, autism is not pathological, but this does not preclude autistic individuals from being disabled or having high support needs. This relatively positive and holistic view of autism has led to a certain degree of friction between autistic individuals, advocates, charities, researchers and practitioners.

Scientists are still trying to determine what causes autism; it is highly heritable and believed to be mainly genetic, but there are many genes involved, and environmental factors may also be relevant. It is unclear why autism frequently co-occurs with attention deficit hyperactivity disorder, epilepsy, intellectual disability, amongst other conditions. There are ongoing disagreements about what should be included as part of the autism diagnosis, whether meaningful sub-types of autism exist, and the significance of autism-associated traits in the wider population. The combination of broader criteria and increased awareness has led to a trend of steadily increasing estimates of autism prevalence, causing a common misconception that there is an autism epidemic and perpetuating the controversial myth that it is caused by vaccines. While autistic people remain autistic throughout their lives, various interventions can help them in different ways. Autistic people with high support needs often benefit from finding and learning other modes of communication and making their environments more accessible.

Classification

Spectrum model

It is now known that autism is a highly variable neurodevelopmental disorder which is generally thought to cover a broad and deep spectrum, manifesting very differently from one individual to another. Some have high support needs, may be non-speaking, and experience developmental delays; this is more likely with other co-existing diagnoses. Other individuals have relatively low support needs; they may have more typical speech-language and intellectual skills but atypical social/conversation skills, narrowly focused interests, and wordy, pedantic communication. They may still require significant support in some areas of their lives. The spectrum model should not be understood as a continuum running from mild to severe, but instead means that autism can present very differently in each individual. How a person presents can depend on context, and may vary over time.

ICD

The World Health Organization's 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:

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). There remain differences, for example Rett syndrome was included in ASD in the DSM-5 but in the ICD-11 it was excluded and placed in the chapter for Developmental Anomalies. Both the ICD and the DSM have been under revision and there has been collaborative work towards a convergence of the two since 1980 (when DSM-3 was published and ICD-9 was current), including more rigorous biological assessment - in place of historical experience - and a simplification of the system of classification.

DSM

The American Psychiatric Association's ''Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision'' ( DSM-5-TR), released in 2022, is the current version of the DSM. The fifth edition, DSM-5, released in May 2013, was the first to define ASD as a single diagnosis, which is continued in DSM-5-TR. ASD encompasses previous diagnoses which included Asperger syndrome, childhood disintegrative disorder, PDD-NOS, and the range of diagnoses which included the word ''autism''. Rather than distinguishing between these diagnoses, the DSM-5 and DSM-5-TR adopt a dimensional approach to diagnosing disorders that fall underneath the autism spectrum umbrella in one diagnostic category. Within this category, the DSM-5 and the DSM includes a framework that differentiates each individual by dimensions of symptom severity, as well as by associated features (i.e., the presence of other disorders or factors which likely contribute to the symptoms, other neurodevelopmental or mental disorders, intellectual disability, or language impairment). The symptom domains are social communication and restricted, repetitive behaviors, with the option of a separate severity - the negative impact of the symptoms on the individual - being specified for each domain, rather than an overall severity. Prior to the DSM-5, the DSM separated social deficits and communication deficits into two domains. Further, the DSM-5 changed to an onset age in the early developmental period, with a note that symptoms may manifest later when social demands exceed capabilities, rather than the previous, more restricted 3 years of age. These changes continue in the DSM-5-TR.

Features and characteristics

For many autistic individuals, characteristics usually first appear during infancy or childhood and generally follow a steady course without remission (different developmental timelines described in more detail below). Autistic people may be severely impaired in some respects but average, or even superior, in others.

Clinicians consider assessment for ASD when a patient shows:

* regular difficulties in social interaction or communication
* restricted or repetitive behaviors (often called " stimming")
* resistance to changes or restricted interests

These features are typically assessed with the following, when appropriate:

* problems in obtaining or sustaining employment or education
* difficulties in initiating or sustaining social relationships
* connections with mental health or learning disability services
* a history of neurodevelopmental conditions (including learning disabilities and ADHD) or mental health conditions.

There are many signs associated with ASD; the presentation varies widely:

:

Atypical eating is also common, but it does not need to be present to make a diagnosis. This paper represents a consensus of representatives from nine professional and four parent organizations in the US.

Some autistic people can exhibit notable ability, for example in mathematics, music or artistic reproduction, which in exceptional cases is usually referred to as savant syndrome. , volume = 70 , issue = 2 , pages = 201–210 , date = April 2018 , pmid = 29691585 More generally, autistic people tend to show a 'spiky skills profile', with strong abilities in some areas contrasting with much weaker abilities in others.

Developmental course

There are two possible developmental courses of ASD. One course of development is more gradual in nature, with symptoms appearing fairly early in life and persisting. A second course of development is characterized by normal or near-normal development before onset of regression or loss of skills, which is known as regressive autism.

Gradual autism development

Most parents report that the onset of autism features appear within the first or second year of life. This course of development is fairly gradual, in that parents typically report concerns in development over the first two years of life and diagnosis can be made around 3–4 years of age. Overt features gradually begin after the age of six months, become established by age two or three years, and tend to continue through adulthood, although often in more muted form. Some of the early signs of ASDs in this course include decreased attention at faces, failure to obviously respond when name is called, failure to show interests by showing or pointing, and delayed imaginative play.

Regressive autism development

Regressive autism occurs when a child appears to develop typically but then starts to lose speech and social skills and is subsequently diagnosed with AS