Autism

Autism, also known as autism spectrum disorder (ASD),^{[lower-alpha 1]} is a condition characterized by differences or difficulties in social communication and interaction, a need or strong preference for predictability and routine, sensory processing differences, focused interests, and repetitive behaviors.^[1] Characteristics of autism are present from early childhood and the condition typically persists throughout life.^[2][3] Autism is classified as a neurodevelopmental disorder,^[4] and a formal diagnosis requires professional assessment that these characteristics cause significant challenges in daily life beyond what would be expected given a person's age and social environment.^[5][6][7][8] Because autism is a spectrum disorder, presentations vary and support needs range from minimal to being non-speaking or needing 24-hour care.^{[9][5][6][10]}

Autism diagnoses have risen since the 1990s, largely because of broader diagnostic criteria, greater awareness, and wider access to assessment.^[11] Changing social demands may also play a role.^[12][13] The World Health Organization estimates that about 1 in 100 children were diagnosed between 2012 and 2021, noting an increasing trend.^{[lower-alpha 2][11][14]} Surveillance studies suggest a similar share of the adult population would meet diagnostic criteria if formally assessed.^[15] This rise has fueled anti-vaccine activists' disproven claim that vaccines cause autism,^[16] based on a fraudulent 1998 study that was later retracted.^[17] Autism is highly heritable and involves many genes, while environmental factors appear to play a smaller,^[18] mainly prenatal role.^[19][20][21] Boys are diagnosed several times more often than girls,^[11][22] and conditions such as anxiety, depression, attention deficit hyperactivity disorder (ADHD), epilepsy, and intellectual disability are more common among autistic people.^[23][24][25]

There is no cure for autism.^[26] Several autism therapies aim to improve self-care, social, and language skills.^[27] Reducing environmental and social barriers helps autistic people participate more fully in education, employment, and other aspects of life.^[28][29][30] No medication addresses the core features of autism, but some are used to help manage commonly co-occurring conditions, such as anxiety, depression, irritability, ADHD, and epilepsy.^[31][32]

Autistic people are found in every demographic group and, with appropriate supports that promote independence and self-determination, can participate fully in their communities and lead meaningful, productive lives.^[33][34] The idea of autism as a disorder has been challenged by the neurodiversity framework, which frames autistic traits as a healthy variation of the human condition.^[35] This perspective, promoted by the autism rights movement, has attracted increasing research attention,^[36] but remains a subject of debate and controversy among autistic people, advocacy groups, healthcare providers, and charities.^[37][38]

The DSM-5 and ICD-11 are the two main diagnostic manuals in use today, and both define autism as a neurodevelopmental disorder with a spectrum of highly varied presentations.^[39][40] The spectrum concept signals diversity rather than a simplistic range from mild to severe.^[41] Before the DSM-5 (2013) and ICD-11/ICD-11 CDDR (2019/2024),^[39][42] autism fell within a broader pervasive developmental disorder category that included labels such as Asperger syndrome and classic autism (also called childhood autism or Kanner syndrome). Because these diagnoses overlapped, the manuals unified them under autism spectrum disorder (ASD).^[43]

Since 1980, the committees behind both manuals have aimed for greater convergence, incorporating biological research while keeping behavior-based criteria.^{[44][45][46][47]} DSM-5 specifies three levels of support needs, from level 1 to level 3.^[48] ICD-11 instead records whether the person has co-occurring intellectual disability or language impairment.^[49]

Some researchers have questioned whether existing criteria capture the full phenomenon, prompting proposals for prototype descriptions, transdiagnostic biological markers, or distinctions between common behavioral traits and rarer genetic or environmental factors.^[50] Others have proposed alternatives to the disorder-focused spectrum model that deconstruct autism into separate phenomena: a non-pathological spectrum of behavioral traits in the general population,^[51] and rare genetic mutations or environmental factors influencing neurodevelopmental and psychological conditions.^[51] Clinical and policy guidance in Australia, the United States, and the United Kingdom now promote neurodiversity-affirming language—for example, using "characteristics" instead of "symptoms" and avoiding words such as "cure".^[52][53][54]

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.^[55] Its fifth edition – DSM-5, released in May 2013 – was the first to define ASD as a single diagnosis,^[56][57] combining the previously distinct diagnoses of classic autism, Asperger syndrome, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified (PDD-NOS).^[57][58] This is still the case in the DSM-5-TR.^{[59][non-primary source needed]}

The DSM-5 and DSM-5-TR adopt a dimensional approach, with one diagnostic category for disorders that fall under the autism spectrum umbrella. Within that category, the DSM-5 has a framework that differentiates individuals by dimensions of symptom severity and by associated features (i.e., the presence of other conditions or factors that may contribute to the symptoms, other neurodevelopmental or mental conditions, intellectual disability, or language impairment).^[59] The two core symptom domains are (a) social communication and (b) restricted, repetitive behaviors. Clinicians may specify separate severity levels for each domain based on the degree to which symptoms affect daily functioning, rather than providing a single overall severity rating.^[60]

Prior to the DSM-5, the DSM separated social deficits and communication deficits into two domains.^[61] The DSM-5 also revised the onset criteria to specify that symptoms appear in the early developmental period, noting that symptoms may manifest later when social demands exceed capabilities; the previous edition had required onset before age three.^[62] These revisions remain in the DSM-5-TR.^[59]

The World Health Organization's International Classification of Diseases (11th revision), ICD-11, was released in June 2018 and came into full effect in January 2022.^[63][44] It describes autism spectrum disorder (6A02) as follows:^[39]

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.

Autism is primarily characterized by differences and difficulties in social interaction and communication, alongside restricted or repetitive patterns of interests, activities, or behaviors (stimming), and, in many cases, distinctive reactions to sensory input. The specific presentation varies widely.^[64][65] Clinicians often consider assessment for autism when these characteristics are present, especially if they are associated with difficulty obtaining or sustaining employment or education, difficulty initiating or maintaining social relationships, involvement with mental health or learning disability services, or a history of neurodevelopmental conditions (including learning disabilities and ADHD) or mental health conditions.^[66][67] In most cases, signs of autism are first observable in infancy or early childhood and remain throughout life.^[68] Autistic people may be significantly disabled in some respects, but average—or, in some cases, superior—in others.^[69][70][71]

Autistic people may have differences in social communication and interaction, which can lead to challenges in environments structured around non-autistic norms. Current diagnostic criteria for autism require difficulties across three social domains: social-emotional reciprocity, nonverbal communication, and developing and maintaining relationships.^[59]

Common early signs of autism include little or no babbling in infancy.^[64] Difficulties may also be apparent in traditional forms of reciprocal social interaction, such as games like peek-a-boo^[64] or pat-a-cake,^[72] as well as in shared attention to objects of interest.^[64] Historically, autistic children were said to be delayed in developing a theory of mind, and the empathizing–systemizing theory proposed that while autistic people may have compassion (affective empathy) for others with similar autistic traits, they often have limited, though not necessarily absent, cognitive empathy.^[73] This may present as social naïvety,^[74] lower-than-average intuitive perception of the meaning or utility of body language, social reciprocity,^[75] or social expectations, including the habitus, social cues, and certain aspects of sarcasm,^[40] which to some degree may be influenced by co-occurring alexithymia.^[76]

Recent research has increasingly questioned these earlier interpretations,^[77] as the double empathy problem theory (2012) proposes that misunderstandings arise mutually between autistic and non-autistic people, rather than solely from autistic deficits in empathy or social cognition.^[78][79] This perspective has contributed to a growing recognition that autistic behavior and communication may reflect different, rather than deficient, social behavior and communication styles.^[77][79] Autistic interests and conversational styles are often characterized by a strong focus in specific topics, a phenomenon known as monotropism.^[80][81]

Autistic people often display atypical behaviors or differences in nonverbal communication. Some may make infrequent eye contact, even when called by name, or avoid it altogether because they find it uncomfortable, distracting, or overstimulating.^[82] They may recognize fewer emotions or interpret facial expressions differently, and may not respond with expressions expected by their non-autistic peers.^[83][84] They can also have difficulty inferring social context or subtext in conversation or text, resulting in different interpretations of meaning.^[85] Speech characteristics such as volume, rhythm, and intonation (prosody) can vary,^[86] and atypical prosody is estimated to occur in at least half of autistic children.^[86]

Signs of autism in childhood include less apparent interest in other children or caregivers, possibly with more interest in objects.^[64] Behaviors that may appear as indifference to non-autistic people often reflect autistic differences in recognizing others' personalities, perspectives, and interests.^[85] Most research has focused on interpersonal relationship difficulties between autistic and non-autistic people and on teaching social skills to address these gaps. However, newer studies indicate that autistic people often form satisfying relationships with other autistic people, which can enhance quality of life.^[87]

Children on the autism spectrum are more likely than their non-autistic peers to be involved in bullying, most often as victims rather than perpetrators or victim-perpetrators.^[88] Among autistic individuals who seek friendships, reduced friendship quantity and quality are often associated with increased loneliness.^[89] Autistic people also face greater challenges in developing romantic relationships than non-autistic people.^[90]

Over time, many autistic people learn to observe and form models of social patterns, and develop coping strategies, such as "masking".^[91] Masking is associated with poorer mental health outcomes as well as delayed diagnosis, which can limit access to appropriate supports.^[91]

The second core feature of autism is a pattern of restricted and repetitive behaviors, activities, and interests. To be diagnosed with autism under the DSM-5-TR, a person must exhibit at least two of the following behaviors:^[59][92]

• Repetitive behaviors: actions such as rocking, hand flapping, finger flicking, head banging, or repeating phrases or sounds (including echolalia^[72]).^[93] These behaviors may occur consistently or primarily when the person is stressed, anxious, or upset. They are also known as stimming. Other examples include playing with toys in ways others might consider limited or unusual^[64] (e.g., arranging toys in a row^[72]).
• Resistance to change: a strong preference for routine, such as performing daily tasks in a specific order or showing distress in response to changes others may consider minor.^[94] The person may become distressed if their routine changes or is disrupted.^[94]
• Focused interests: intense interest in a particular activity, topic, or hobby, often accompanied by sustained attention and deep knowledge; for example, a strong attachment to certain objects^[59] or frequent discussion of a specific topic.^[95]
• Sensory reactivity: atypical responses to certain sensory inputs, such as aversion to specific sounds or textures, fascination with lights or movement, or apparent indifference to pain or temperature.^[96]

It is increasingly argued that these characteristics should be accepted, which is supported by their recognized functions, such as self-regulation.^[97] Focused interests can also provide personal fulfillment and contribute to the development of specialized knowledge.^[98] A distinction should be made between these features and those of obsessive–compulsive disorder, which can co-occur with autism and involves compulsions or obsessions aimed at preventing feared outcomes.^[99]

Differences in verbal communication become noticeable in childhood, as many autistic children develop language skills at an uneven pace. Verbal communication may develop later or never (non-speaking autism), while reading ability may be present before school age (hyperlexia).^[84] Less joint attention may distinguish autistic from non-autistic infants.^[100] Infants may show later onset of babbling, unusual gestures, lower responsiveness, and vocal patterns that are not synchronized with the caregiver. In their second and third years, autistic children may have less frequent and less diverse babbling, consonants, words, and word combinations, and their gestures may be less often integrated with words. Autistic children are less likely to make requests or share experiences and more likely to simply repeat others' words (echolalia).^[101] Around 25–35% of autistic school-age children are non-speaking or minimally speaking.^[102] The age at which a child acquires speech and the complexity of their early language development are significant predictors of their verbal communication abilities in later life.^[102]

Self-harm is approximately three times more common in autistic people than non-autistic people.^[103] This behavior includes head-banging, hand-biting, and skin-picking, and can lead to serious injury or, in rare cases, death.^[104] Multiple theories explore the development and persistence of self-harm within developmental conditions, including autism.^[105] Explanations include communication difficulties, leading people to use self-injury as a way to express needs, distress, or other messages.^[104] Additionally, self-harm may be linked to efforts to regulate sensory input^[106] or modulate pain perception, particularly for those experiencing chronic discomfort or medical conditions.^[105] Neurological factors are also under investigation, with anomalies in basal ganglia connectivity suggested as a potential biological predisposition in some autistic people.^[105]

Several models that are not formal medical diagnoses have been used to describe and conceptualize challenges that autistic people face in their daily lives.^[107] They lack formal diagnostic criteria, but are described by autistic people.^[107][108]

Autistic fatigue or an autistic burnout is a prolonged state of intense mental and physical symptoms, notably exhaustion.^{[109][108][107][110]} It is described as distinct from but similar to occupational burnout, resulting from pressure to camouflage or mask autistic traits in social interactions.^[108][109] The term "autistic burnout" was first used in 2008, with research into the phenomenon undertaken in the 2020s.^[109] Several researchers have made characterizations of autistic burnout, but there is no consensus on the definition criteria. Depression can be misattributed to autistic burnout, as they have several overlapping criteria. Solutions used to overcome burnout include reduced masking, increased stimming, engaging in special interests and in familiar activities, and getting relief from stress. Some affected people temporarily withdraw from social contacts as a recovery strategy; while providing relief, interpersonal withdrawal can also result in loneliness and worsening mental health. There is little data on professional solutions.^[109]

Autistic inertia is a difficulty experienced among autistic people with initiating, transitioning between, or stopping activities or mental states.^[108] It can manifest as a feeling of being "stuck", where people find it challenging to begin a task, shift focus to a different activity, or disengage from an action, even when they want to.^[107]

A meltdown may arise if, upon processing large amounts of information, an autistic person experiences anxiety or feels overwhelmed.^[111] Triggers may be sensory or social, and include unpredictability, unmet basic needs, and emotional situations, and often accumulate.^[111] A meltdown can be expressed audibly (e.g., screaming or crying) or physically.^[111] The person often shows signs of distress beforehand, such as pacing, asking repetitive questions, trembling, or sweating.^[111] An autistic shutdown is similar, but inward, and the autistic person is often unable to speak or withdraws completely.^[111] Meltdown or shutdown can be prevented by eliminating the distressing factors.^[111] They may be ameliorated by avoiding further questions or pressure, showing the person that one is there to help, and allowing the person to calm down by leaving the situation or breathing slowly.^[111]

Autistic people may exhibit traits or characteristics that are not part of the formal diagnostic criteria but can nonetheless affect their personal well-being or family dynamics.^[112]

• An estimated 60–80% of autistic people have motor signs that include poor muscle tone, poor motor planning, and toe walking;^[113][114] difficulties in motor coordination are pervasive across the autism spectrum.^[115][116]
• Unusual or atypical eating behavior occurs in about 70% of children on the autism spectrum,^[117] to the extent that it was formerly a diagnostic indicator.^[112] Selectivity is the most common characteristic, although eating rituals and food refusal also occur.^[117]
• Most studies report moderate correlations between autism, Internet addiction disorder, and video game addiction.^[118]

Autistic people tend to show a "spiky skills profile", with strong abilities in some areas and much weaker abilities in others.^[119] Some autistic people show unusual or notable abilities, ranging from splinter skills (such as memorization of trivia) to rare talents in mathematics, music, or artistic reproduction, which in exceptional cases are considered a part of the savant syndrome.^[120][121] Some autistic people demonstrate superior skills in perception and attention relative to the general population.^[122]

Families who care for an autistic child face greater stress.^[123] Parents may struggle to understand their child and to find appropriate care options. Affiliate stigma also decreases quality of life, where negative attitudes toward the autistic child are extended to those close to the child.^[124] Family members who are themselves autistic are often better able to understand the autistic child.^[87]

The exact causes of autism are unknown,^{[125][126][127][128]} with genetics likely being the largest contributing factor. It was long presumed a single cause at the genetic, cognitive, and neural levels underpinned the social and non-social features.^[129] Increasingly, autism is assumed to be a complex condition with distinct, often co-occurring, causes for its core aspects.^[129][130] It is unlikely that autism has a single cause;^[130] research has identified many factors as potential contributors,^[131] including genetics,^[92] prenatal and perinatal (shortly after birth) history,^[131] neuroanatomical anomalies, changing social demands in the workplace or in school,^[12] and environmental influences.^[131] It is possible to identify general factors, but difficult to determine specific ones.^[132] Research into causes is complex due to challenges in identifying distinct biological subgroups within the autistic population.^[133]

Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether autism is explained more by rare mutations with major effects, or by rare multi-gene interactions of common genetic variants.^[134][135] Twin studies indicate that autism is highly heritable, with genetic factors explaining most of the risk and shared environmental effects playing a minor role.^[18] Numerous genes have been found, with most loci individually explaining less than 1% of autism cases^[136] and having only small effects.^[134] While these genetic variants are associated with a higher likelihood of being autistic, they do not individually determine whether someone will be autistic.^[137] Complexity arises due to interactions among multiple genes, the environment, and heritable epigenetic factors (which influence gene expression without changing DNA sequence).^[138]

Typically, autism is not traceable to a single-gene (Mendelian) mutation or chromosome anomaly, and no associated genetic syndrome selectively causes autism.^[134] If autism is one characteristic of a broader medical condition, such as fragile X syndrome, it is referred to as syndromic autism, as opposed to non-syndromic or idiopathic autism, which is typically polygenic without a known cause.^[139] Syndromic autism is present in approximately 25% of autistic people.^[140] Research has suggested that autistic people with intellectual disability tend to have rarer, more impactful, genetic mutations than those found in people diagnosed solely with autism.^[141] A number of genetic syndromes causing intellectual disability may also be co-occurring with autism, including fragile X, Down, Prader–Willi, Angelman, Williams syndrome,^[142] and SYNGAP1-related intellectual disability.^[143]

Research suggests that autism is associated with genes that influence neural development and connectivity. These are involved in key neuronal processes such as protein synthesis, synaptic activity, cell adhesion, and the formation and remodeling of synapses, as well as the regulation of excitatory and inhibitory neurotransmission. Studies have identified lower expression of genes linked to the inhibitory neurotransmitter gamma-aminobutyric acid, alongside higher expression of genes associated with glial (e.g., astrocytes) and immune (e.g., microglia) cells, correlating with higher numbers of these cells in post-mortem brain tissue. Genes associated with variation in the mTOR signaling pathway, which is involved in cell growth and survival, are also under investigation.^[144] Some hypotheses from evolutionary psychiatry propose that certain autism-associated genes may persist in the population due to their links to traits such as intelligence, systemising abilities, or innovation.^[145]

If parents have one autistic child, the chance of having a second autistic child ranges from 7% to 20%.^[92] Although autism is highly heritable, many autistic people have only non-autistic family members. In some cases, this may be explained by de novo structural variations—such as deletions, duplications, or inversions—that arise spontaneously during meiosis and are not present in the parents' genomes.^[146][147] The likelihood of being autistic is greater with older fathers than with older mothers; two potential explanations are the known increase in the number of mutations in older sperm and the hypothesis that men marry later if they carry a genetic predisposition and show some signs of autism.^[148]

Research exploring the evolutionary advantages of autism and associated genes has suggested that autistic people may have contributed uniquely to human development, particularly in technological innovation (such as tool-making) and in the detailed observation and analysis of the natural environment.^[149] Systematic reviews emphasize that these ideas remain speculative and that no single evolutionary explanation has been established.^[150]

Social factors such as upbringing are not known to cause autism, but it is possible that increasing demands for flexibility and social interaction in education, or in one's personal and professional life, may cause people to exhibit pronounced difficulties that would not have led to diagnosis in a different setting.^[12][13]

Various theoretical frameworks attempt to integrate underlying genetic and environmental causes with observed neurobiological findings and behavioral traits. For instance, the Intense World Theory proposes that a higher neural responsiveness in autism leads to more intense sensory perception, attention, memory, and emotional responses, shaping the person's experience.^[151] The Enhanced Perceptual Functioning model of autism posits that superior and more independent functioning of auditory and visual perception is the root cause of the specific pattern of cognitive, behavioral, and neural performance observed in autistic people.^[29] The model asserts the importance of perception, arguing it is more central to the autistic phenotype than social or higher-order cognitive processes.^[29]

Beyond models of causation and brain function, cognitive theories have been developed to explain patterns of information processing common in autistic people, to better understand the autistic phenotype.^[152] This includes theories suggesting a tendency to focus on details over broader context (weak central coherence theory), and distinct cognitive styles related to analyzing systems versus empathizing with others (empathising–systemising theory).^[152] While these cognitive accounts describe how autistic traits may manifest, they are generally viewed as explanations of the behavioral and cognitive consequences of the underlying neurobiological development rather than primary causes themselves.^[152]

Certain factors during pregnancy and birth may increase the likelihood of autism,^[153] although no single factor is conclusive and study results are often inconsistent.^[154] These factors include advanced parental age,^[155][156] maternal health conditions (e.g., gestational diabetes, infections such as rubella,^[157] inflammation^[158]), exposure to certain medications (e.g., valproate^[154]), and some environmental exposures like significant air pollution during pregnancy.^[159] While many environmental factors have been investigated, few have established links,^[154] and some prominent claims (e.g., vaccines or parenting styles) have been disproven.^[160]

Work on autism in the mid-20th century proposed the "frigid mother" or refrigerator mother hypothesis, according to which poor parenting or lack of emotional support from parents leads to autism.^[161] When it was proposed, the hypothesis contributed to considerable media attention about autism, which had previously been mostly ignored.^[162] The hypothesis has since fallen out of favor, and has not garnered support when studied.^[161] But the blame placed on parents of children on the autism spectrum, especially mothers, has contributed to substantial stigma.^[163][164]

Early social experiences, such as caregiver interactions or deprivation, may shape the development of autism, potentially via gene–environment correlations, and are distinct from the discredited refrigerator mother hypothesis.^[21]

Parents may first become aware of autistic characteristics in their child around the time of a routine vaccination. This has led to theories – subsequently disproven – blaming vaccine "overload", the vaccine preservative thiomersal, or the MMR vaccine for causing autism.^[165] In 1998, British physician Andrew Wakefield led a fraudulent, litigation-funded study that suggested that the MMR vaccine may cause autism.^{[166][167][168][169][170]} His co-authors have since recanted the claims made in the study.^[171] Wakefield was struck off the British medical register for "serious professional misconduct" after determination that his involvement in the study amounted to fraud, leading to the loss of his right to practice medicine.^[172]

Two versions of the vaccine causation hypothesis were that autism results from brain damage caused by either the MMR vaccine itself,^[16] or by mercury used as a vaccine preservative.^[173] No convincing scientific evidence supports these claims.^[16] They are biologically implausible,^[165] and further evidence continues to refute them, including the observation that the rate of autism continues to climb despite elimination of thimerosal from most routine vaccines given to children from birth to 6 years of age.^{[173][174][175][176][177]}

A 2014 meta-analysis examined ten major studies on autism and vaccines involving 1.25 million children worldwide; it concluded that neither the vaccine preservative thimerosal (mercury), nor the MMR vaccine, which has never contained thimerosal,^[178] lead to autism.^[179] Despite this, misplaced parental concern has led to lower rates of childhood immunizations, outbreaks of previously controlled childhood diseases in some countries, and the preventable deaths of several children.^[180][181]

Currently, there is no cure for autism.[26] From the perspective of neurodiversity, "curing" or otherwise treating autism may not be an appropriate goal.[53][182]

Interventions targeting specific challenges or co-occurring conditions associated with autism are widely regarded as important.^[183] Perspectives on the goals of these interventions vary: the medical model of disability often focuses on addressing core characteristics such as social communication difficulties and restricted/repetitive behaviors.^[184] The neurodiversity movement supports interventions aimed at enhancing functional communication (spoken or non-spoken), managing related issues like anxiety or inertia, or addressing behaviors considered harmful, rather than seeking to alter core autistic features.^[185][184]

Studies of interventions have methodological problems that prevent definitive conclusions about efficacy,^[186] but the development of evidence-based interventions has advanced.^[187] Several therapies can help autistic children,^[188] and they are typically tailored to the child's needs.^[189] The main goals of therapy are to lessen associated difficulties and family distress, and to increase quality of life and functional independence. In general, higher IQs correlate with higher responsiveness to interventions and larger intervention outcomes.^[190][187] Behavioral, psychological, educational, and skill-building interventions may be used to help autistic people learn skills for living independently, as well as other social, communication, and language skills.^[27] Therapy also aims to reduce behaviors perceived as inappropriate and to build upon strengths.^[191] Medications have not been found to reduce autism's core features, but may be used for associated difficulties, such as irritability or inattention.^[192]

Certain interventions, such as intensive, sustained special education, remedial education programs, and behavior therapy, are considered beneficial early in life for autistic children to acquire self-care, social, and job skills.^[193] Available approaches include applied behavior analysis, developmental models, structured teaching, speech and language therapy, cognitive behavioral therapy,^[194] social skills therapy, and occupational therapy.^[189] These interventions may either target autistic features comprehensively or focus on a specific area of difficulty.^[187]

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Applied behavior analysis (ABA) is a behavioral therapy that aims to teach autistic children certain social and other behaviors by prompting using rewards and reinforcement learning. This includes learning fine and gross motor and language skills through play, expressive labeling, and requesting. It also seeks to reduce aggressive and self-injurious behavior by assessing its environmental causes and reinforcing replacement behaviors. Early, intensive ABA therapy has demonstrated effectiveness in enhancing preschool children's language skills, adaptive functioning, and intellectual performance.^{[195][196][197][198]} Another review reported a lack of adverse event monitoring, although such adverse effects may be common.^[199]

Interventions for early childhood may be based on different theoretical frameworks, such as ABA (with its structured and naturalistic approaches) and Developmental Social Pragmatic (DSP) models.^[187] Research indicates that in acquiring spoken language, autistic children with higher receptive language skills tend to make progress with fewer hours (2.5 to 20 per week) of a naturalistic approach, whereas those with lower receptive language skills tend to show more progress only with a greater intensity of intervention (25 hours per week) using discrete trial training, a structured form of ABA.^[195][197]

ABA has faced criticism.^{[200][201][202]} Sandoval-Norton et al. describe it as unethical and argue that it has unintended consequences, such as prompt dependency, susceptibility to psychological abuse, and overemphasis on compliance, which can create challenges in the transition to adulthood.^[200] Increasingly, ABA is also criticized for trying to reduce or eliminate autistic behaviors to make children appear less autistic, rather than respecting neurodiversity.^[203] A problem with unreported conflicts of interest in ABA research has been described, with potential effects on the quality of evidence.^[204] In response, some ABA advocates suggest that instead of discontinuing the therapy, efforts should focus on increasing protections and ethical compliance.^[205]

A related type of intervention is parent training models.^[187] These teach parents to implement various ABA and DSP techniques themselves. Several parent-mediated behavioral therapies target social communication difficulties, while their effect on restricted and repetitive behaviors (RRBs) is uncertain.^[206] Similarly, teacher-implemented interventions that combine naturalistic ABA with a developmental social pragmatic approach have been associated with effects on young children's social-communication behaviors, although there is limited evidence regarding effects on broader autistic characteristics.^[187]

Inclusive education models strive to support autistic students in mainstream educational settings, moving away from segregated special education environments toward participation alongside their peers.^[207] Despite these efforts, autistic students can face significant barriers, sometimes leading to trauma or emotionally-based school non-attendance.^[207][208] This avoidance is often rooted in overwhelming sensory environments, social anxieties, communication breakdowns, bullying, or lack of adequate support and understanding, rather than defiance.^[207][208]

Central to successful inclusion is the application of frameworks like Universal Design for Learning (UDL), which proactively designs curricula and learning environments to be accessible and engaging for all students, including those who are autistic.^[209] UDL principles accommodate varied learning styles, sensory sensitivities, and communication preferences often present in autistic people.^[209]

The SPACE framework (sensory, predictability, acceptance, communication, empathy) developed by Doherty et al. primarily for healthcare settings offers a lens for identifying and addressing common environmental barriers that can contribute to distress and avoidance behaviors for autistic people.^[28] Accommodations may include providing quiet spaces as a retreat for people feeling overwhelmed.^[210] Autistic students may also need help initiating and maintaining social relationships with their peers if they wish to do so.^[207] Especially in higher education, some autistic students may need help with executive functioning, e.g., managing their own work, and the ability to initiate and complete tasks.^[211]

Transitioning to adulthood, autistic people often encounter substantial barriers to securing and maintaining meaningful employment, leading to high rates of unemployment and underemployment compared to the general population.^[30] Challenges can include navigating traditional interview processes,^[212] difficulties with unspoken social rules in the workplace, sensory sensitivities to office environments (e.g., lighting, noise), and needs for clear, direct communication and structured tasks.^[30][213] Effective workplace inclusion involves implementing reasonable adjustments such as flexible working hours or locations, providing noise-canceling headphones, staff training, and mentorship programs.^[30][213] Working from home can help to avoid overwhelming sensory or social situations, even if this means losing desirable social contact.^[214][215] Autism-friendly workplaces not only allow autistic employees to utilize their unique skills and perspectives but also benefit employers through increased innovation, problem-solving capabilities, and employee loyalty.^[213][216]

Autistic people may be prescribed medication to manage specific co-occurring conditions or behaviors, such as ADHD, anxiety, aggression, or self-injurious behaviors, particularly when non-pharmacological interventions alone have been insufficient.^[217][218] Medications are not routinely recommended for autism's core features, such as social and communication difficulties or restricted and repetitive behaviors.^[219]

More than half of autistic children in the United States are prescribed psychoactive drugs or anticonvulsants.^[220] Commonly used drug classes include antidepressants, stimulants, and antipsychotics.^[220] Among antipsychotics, risperidone and aripiprazole are the only medications approved by the U.S. Food and Drug Administration specifically for reducing irritability, aggression, and self-injurious behaviors in autistic people.^[192][221] These drugs can have significant side effects and responses to them may vary.^[192] The UK's National Health Service cautions against the overprescription of antipsychotics and recommends their use only for specific indications, at the lowest effective dose and for the shortest duration necessary.^[222]

Some research suggests that risperidone and aripiprazole may also reduce restricted and repetitive behaviors, such as hand-flapping or body-rocking.^[219] The evidence supporting this use has limitations, including study size and scope, alongside concerns about adverse effects.^[223] A meta-analysis found no significant efficacy of these antipsychotics or SSRI antidepressants in reducing these behaviors.^[224] Stimulant medications like methylphenidate may reduce inattention or hyperactivity in some autistic children, particularly when ADHD is also present.^[189] But methylphenidate's efficacy is lower in autistic people with ADHD compared to non-autistic people with ADHD, and side effects are more common.^[225]

Alternative therapies have been researched and implemented, and many have resulted in harm to autistic people.^[189] For example, chelation therapy is not recommended as a treatment for autism, with risks outweighing potential benefits.^[226] Reports of death from botched chelation therapy as treatment for autism have been documented.^[227][228] Medical authorities have condemned bleach-based approaches, such as chlorine dioxide solutions marketed as Miracle Mineral Solution, as dangerous and ineffective.^[229] The British NHS also warns against CEASE therapy, which rejects vaccinations and recommends potentially harmful amounts of dietary supplements.^[230] There is also no evidence for the efficacy of hyperbaric oxygen therapy and its use is not recommended.^[231]

Although sometimes used for autistic people, no reliable evidence indicates a gluten- and casein-free diet as a standard intervention.^{[232][233][234]} Autistic children's preference for unconventional foods as well as gastrointestinal problems and lack of exercise can lead to reduction in bone cortical thickness, and this risk is greater in those on casein-free diets, as a consequence of the low intake of calcium and vitamin D.^[235]

Interventions for autistic adults have limited evidence; cognitive behavioral approaches and mindfulness are considered promising.^[236] Music therapy for autistic people likely improves overall autism severity, global functioning, and quality of life, but evidence is unclear for social and communication skills.^[237] Animal-assisted activities and therapies show promise in improving social communication, irritability, hyperactivity, and word usage in autistic people.^[238]

With appropriate supports that promote independence and self-determination, autistic people can participate fully in their communities and lead meaningful, productive lives.^[33][34] Autism typically persists whether diagnosed in children or in adults, but those who no longer meet the criteria for diagnosis may have it removed.^[3] Some report that those with limited support needs are likely to have lessened autistic features over time,^[239] while others argue that this perception is likely due to masking; i.e., hiding autistic characteristics to avoid stigma.^[240] About 85% of autistic people need support with independent living in adulthood.^[241] Factors such as developing spoken language before age six, having an IQ above 50, and possessing marketable skills are associated with a higher likelihood of independent living in adulthood.^[242]

Risk factors for self-harm and suicidality include circumstances that could affect anyone but are more common among autistic people, such as mental health problems (e.g., anxiety disorder) and social problems (e.g., unemployment and social isolation). In addition, there are autism-specific factors, such as exhausting attempts to behave like a non-autistic person to avoid stigma and negative reactions of society towards autistic people (masking).^[243] Autistic people are also at significantly increased risk of victimization, including bullying, sexual assault, and other forms of criminal abuse.^[244] A 2019 meta-analysis found autistic people to be four times more likely to have depression than non-autistic people.^[245]

Rates of suicidality vary significantly depending upon what is being measured.^[243] This is partly because questionnaires developed for non-autistic subjects are not always valid for autistic people.^[243] As of 2023, the Suicidal Behaviours Questionnaire–Autism Spectrum Conditions (SBQ-ASC) is the only test validated for autistic people.^[243] According to some estimates, about a quarter of autistic youth^[246] and a third of all autistic people^[243][247] have experienced suicidal ideation at some point. Autistic people are about three times as likely as non-autistic people to make a suicide attempt.^[103][248] Almost 10% of autistic youth^[246] and 15% to 25% of autistic adults^[243][247] have attempted suicide. Rates of suicide attempts and suicidal ideation are the same for people formally diagnosed with autism and people who have typical intelligence and are believed to be autistic but have not been diagnosed.^[243] The suicide risk is higher for autistic people who are not cisgender males and do not have intellectual disabilities.^[243][248]

Autism occurs in every country and demographic group.^[33][11][14] Most professionals believe that race, ethnicity, and socioeconomic background have limited effect on the occurrence of autism.^[249]

Research indicates that autistic people are significantly more likely to be LGBTQ than the general population.^[250] Autistic people are also significantly more likely to be non-theistic or non-religious.^[251]

Several conditions can co-occur with autism at a higher rate than in the rest of the population.^[252] This may be referred to as comorbidity, and may increase with age, causing difficulties for youth on the autism spectrum, and can make interventions and therapies more challenging. Features of autism and other diagnoses often overlap, and autism's characteristics can make traditional diagnostic procedures more difficult.^[253][254] This is sometimes known as diagnostic overshadowing.^[255] Common co-occurring conditions are:

• ADHD is seen in between 25% to 32% of autistic people.^[256] Characteristics similar to those of ADHD can be part of an autism diagnosis.^[257]
• Epilepsy occurs in about 10% of autistic people.^[258] The risk is higher for older autistic people and those with intellectual disability.^[259]
• Intellectual disabilities are some of the most common co-occurring conditions with autism (30% to 40%).^[260] As diagnosis is increasingly given to people with lower support needs, there is a tendency for the proportion with co-occurring intellectual disability to decrease over time.
• Various anxiety disorders can co-occur with autism, with overall co-occurring rates of 17% to 23%.^[256] Many anxiety disorders have characteristics better explained by autism itself, or are hard to distinguish from autism's features.^[261]
• Rates of co-occurring depression in autistic people range from 9% to 13%.^[256]
• Obsessive–compulsive disorder (OCD) occurs in 7% to 10% of autistic people.^[256]
• Starting in adolescence, some autistic people fall under the criteria for the similar-looking schizoid personality disorder, which is characterized by a lack of interest in social relationships, a tendency toward a solitary or sheltered lifestyle, secretiveness, emotional coldness, detachment, and apathy.^[262]
• Genetic conditions: About 10% of autistic people are diagnosed with a rare genetic syndrome such as Prader–Willi, Angelman, Fragile X, or 16p11.2 deletion syndrome.^[263]
• Gastrointestinal problems are one of the most commonly co-occurring medical conditions in autistic people.^[264] These are linked to greater social difficulties, irritability, language difficulties, mood changes, distressed behavior, and sleep problems.^[264][265]
• Sleep problems affect about two-thirds of autistic people at some point in childhood. These most commonly include symptoms of insomnia, such as difficulty falling asleep, frequent nocturnal awakenings, and early-morning awakenings. Sleep problems are associated with difficult behaviors and family stress, and are often a focus of clinical attention over and above the autism diagnosis.^[266]
• Motor difficulties, including features of dyspraxia, are highly prevalent in autistic people,^[267] and there is a significantly higher rate of joint hypermobility/hypermobility spectrum disorders/Ehlers-Danlos syndrome in autistic people.^[268]
• There is tentative evidence that gender dysphoria occurs more frequently in autistic people.^[269][270]

The World Health Organization estimates that about 1 in 100 children were autistic between 2012 and 2021 with a trend of increasing prevalence over time. This may reflect an underestimate of prevalence in low- and middle-income countries.^[11][14] Surveillance studies in community samples of adults suggest a similar share of the adult population would meet diagnostic criteria if formally assessed.^[15] The number of people diagnosed has increased since the 1990s, likely due to a combination of increased recognition of autism, better availability of diagnosis, and changes to the diagnostic criteria.^[11] The increase in autism is largely attributable to changes in diagnostic practices, referral patterns, availability of services, age at diagnosis, and public awareness,^{[271][272][273]} particularly among women,^[274] though other unidentified environmental factors may exist.^[275]

The Centers for Disease Control's Autism and Developmental Disabilities Monitoring Network reported that approximately 1 in 31 children in the United States is diagnosed with autism, based on data collected in 2022.^[276] For 2016 data, the estimate was 1 in 54, compared to 1 in 68 in 2010 and 1 in 150 in 2000.^[276] Diagnostic criteria for autism have changed significantly since the 1980s; for example, U.S. special-education autism classification was introduced in 1994.^[277]

Males are about three times more likely to be diagnosed with autism than females.^[22] Several theories about the higher prevalence in males have been investigated.^[278] Females, for example, are more likely to have associated cognitive disability, suggesting that less obvious forms of autism are likely being overlooked.^[279] Prevalence differences may also be a result of gender differences in expression of characteristics, with autistic women and girls showing less atypical behaviors and therefore being less likely to be diagnosed with autism.^[280]

In 1911, Swiss psychiatrist Paul Eugen Bleuler coined the German term Autismus to characterize the social withdrawal he observed in people with schizophrenia.^[281] Rendered in English as autism, the term derives from the Greek word autos ("self").^[282] Bleuler used the term for a symptom of adult schizophrenia: a person's retreat from reality into their own subjective world. He also mentioned "autistic thinking" as a fleeting, illogical thought process everyone experiences. In the mid-1920s, German psychiatrist Fritz Künkel categorized over 100 schizophrenic patients into four groups, one of which he labeled "autistic", highlighting disturbances in emotional life. In 1926, building on his work and Bleuler's, Grunya Sukhareva published an article about six boys who were musically gifted and had a tendency toward abstract thinking. She called their affects "flattened" and their tendency to avoid other children an "autistic attitude".^[283] Scholars have credited Sukhareva with making observations that closely mirror ASD as described by the DSM-5 and ICD-11.^[284] Her work expanded on the definition throughout her career while making great strides in differentiating ASD and schizophrenia nearly 30 years before the establishment of separate classifications for these diagnoses with the 1980 publication of the DSM-III.^[285]

The autistic rights and neurodiversity movements argue autism should be accepted as a difference to be accommodated instead of cured,^{[287][288][289][290][291]} although a minority of autistic people might still accept a cure.^[292] Social-science scholars study autistic people in hopes of learning more about "autism as a culture, transcultural comparisons ... and research on social movements".^[291] Events related to autism include World Autism Awareness Day, Autism Sunday, Autistic Pride Day, Autreat, and others.^{[293][294][295][296]}

Focused interests are commonly found in autistic people and can include activism. Environmental activist Greta Thunberg has spoken favorably about her autism diagnosis, saying that autism can be a source of life purpose, as well as the basis of careers, hobbies, and friendships.^{[297][298][286]} Entrepreneur and co-founder of Microsoft Bill Gates has written, "If I were growing up today, I probably would be diagnosed on the autism spectrum."^[299]

In some countries, people with an autism diagnosis are required to provide additional proof of suitability to apply for a driver's license^[300] or to handle firearms.^[301] They may face barriers to entering military service.^[302]

Autistic people may face discrimination of various kinds, both directly and indirectly, in a variety of settings, professional, educational, or clinical.^[303] Such discrimination is often initiated after other people identify the autistic person as different from themselves, which may occur very quickly.^[303] This discrimination sometimes leads to violence, assault, or social exclusion.^[303] Various legal limitations on people with an autism diagnosis have also been considered discriminatory.^[300][301]

Some autistic people and affiliated researchers^[304] have advocated a shift in attitudes toward the view that autism is a difference, rather than a disease that ought to be treated or cured.^[305][306] Critics have bemoaned the entrenchment of some of these groups' opinions, and that they speak to a select group of autistic people with limited difficulties.^{[289][307][291][308][309]}

The neurodiversity movement and the autism rights movement are social movements within the context of disability rights, emphasizing the concept of neurodiversity, which describes the autism spectrum as a result of healthy and valuable variations in the human brain rather than a disorder to be cured.^[289][310] The autism rights movement advocates including greater acceptance of autistic behaviors, therapies that focus on coping skills rather than imitating the behaviors of non-autistic people,^[311] and the recognition of the autistic community as a minority group.^[311][309] Autism rights or neurodiversity advocates believe that the autism spectrum is genetic and should be accepted as a healthy variation in the human genome.^[289] These movements are not without detractors. A common argument against neurodiversity activists is that most have relatively low support needs, or are self-diagnosed, and do not represent the views of autistic people with higher support needs.^{[309][312][313]} The argument has been made that only autistic people with lower support needs should be included under the neurodiversity banner, as autism with high support needs "may rightfully be viewed as a disability".^[309] The concept of neurodiversity is contentious in autism advocacy and research groups and has led to infighting.^[307][291]

• "Neurodevelopmental Disorders". Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR). Washington, DC: American Psychiatric Association. 18 March 2022. ISBN 978-0-89042-577-0. 
• "6A02 Autism spectrum disorder". International Classification of Diseases 11th Revision (ICD-11). World Health Organization. February 2022. 6A02. https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/437815624. Retrieved 14 May 2022. 

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• World Health Organization fact sheet on autism

Classification	D ICD-11: 6A02 ICD-10: F84.0 ICD-9-CM: 299.00 OMIM: 209850
External resources	Medicine:Curlie: Autism MedlinePlus: 001526 Patient UK: Autism

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