INTRODUCTION — Autism spectrum disorder (ASD) is a biologically based neurodevelopmental disorder characterized by persistent deficits in social communication and social interaction, and restricted, repetitive patterns of behavior, interests, and activities.
The clinical features of ASD will be reviewed here. Related topics are presented separately:
TERMINOLOGY — The terminology and diagnostic criteria for ASD vary geographically. (See "Autism spectrum disorder in children and adolescents: Evaluation and diagnosis", section on 'Diagnostic criteria' and "Autism spectrum disorder in children and adolescents: Terminology, epidemiology, and pathogenesis", section on 'Terminology'.)
●"Autism spectrum disorder" is the term used by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR), which is used predominantly in the United States .
●The World Health Organization International Classification of Diseases, 11th Revision (ICD-11) is used in other countries throughout the world .
PHENOTYPIC SPECTRUM AND CLINICAL PRESENTATION — ASD is a heterogeneous neurodevelopmental disorder with a broad range of clinical manifestations of atypical social communication and social interaction, and restricted, repetitive patterns of behavior [3-5]. The various clinical presentations include (but are not limited to):
In this age group, ASD commonly presents when the caregivers or the primary care provider notice speech/language delays. Less commonly, they may notice failure to make eye contact and limited interest in socializing. Failure to pass an ASD screening test (eg, Modified Checklist for Autism in Toddlers) is also likely to generate a concern about ASD. (See "Autism spectrum disorder in children and adolescents: Surveillance and screening in primary care", section on 'Early indicators'.)
●Plateau of social skills after typical early development.
Approximately one-fourth to one-third of children with ASD achieve early language milestones but have regression or plateau of language, communication, and/or social skills between 15 to 24 months of age [4,12-16]. The regression of skills can be gradual or sudden and may occur in the context of preexisting developmental delays or atypical development .
●Lack of interest in socializing, absent or delayed speech/language skills, marked resistance to change, and restricted interests are common features for older toddlers and preschoolers .
●Children with a less severe phenotype may initially present in kindergarten or later. They may present with behavior disturbances (eg, disruptive behaviors, difficulty following instructions because of over-focus on preferred interests) or with symptoms of a co-existent condition such as attention deficit hyperactivity disorder or anxiety. Atypical social and language development may only become apparent upon a more careful review of the child’s overall development .
IMPAIRED SOCIAL COMMUNICATION AND INTERACTION — Social communication refers to the verbal and nonverbal skills needed for successful communication between two or more conversational partners . Whereas language is critical in communication, so too are the nonverbal skills that so often give deeper meaning to spoken words. Social communication includes sharing thoughts, intentions, and feelings . Successful social communication and interaction requires several overlapping skills and behaviors, as described in the sections below.
Whereas delays and deviations in language development are one of the most common presenting complaints of caregivers of children with ASD [21,22], children with ASD may lack the intent to communicate and socialize. They may be unable to register, recognize, and/or understand the social communication behaviors of others . (See "Autism spectrum disorder in children and adolescents: Evaluation and diagnosis", section on 'Diagnostic criteria'.)
Impaired social interaction can be difficult to distinguish from impaired language skills or global cognitive delays, which commonly co-occur with ASD. A clear understanding of social cognition and social communication helps to differentiate social interaction problems related to ASD from those related to other developmental differences.
●Social attention – Social attention refers to the amount of attention dedicated to social phenomena. It is measured by the frequency, duration, and complexity of behaviors related to socializing . These behaviors include observing and watching others, imitating others, sharing emotions (empathizing) with others, making eye contact with others, smiling or standing near to someone to show social interest, calling a peer by name, or responding to social bids from others.
In children with ASD, social attention behaviors are limited in frequency, duration, and/or complexity. They may also appear to be atypical. Examples include [20,24,25]:
•Absent or limited interest in social interaction with other children (including siblings); only interacting to get personal needs met.
•Lack of social play behaviors, such as copying the play of peers and vocational actions of adults.
•Inappropriate response to another's bid for social interaction (eg, failure to make eye contact when called by name).
•Getting too close to the social partner and not noticing that this makes the social partner uncomfortable; indifference or aversion to socially motivated physical contact and affection.
•Atypical or poorly coordinated social attention behaviors (despite social motivation) – Atypical social behaviors can manifest as speaking without concomitant nonverbal communication behaviors such as making eye contact. Alternatively, a child with ASD may push a peer to gain social attention without also initiating a conversation or making other, more appropriate attempts at socializing.
●Joint attention – Joint attention is a more sophisticated form of social attention because it includes awareness of the social attention of others. In joint attention, two or more communication partners are paying attention to a person, topic or activity, while simultaneously communicating to each other (verbally or nonverbally) that the focus of attention is shared . Joint attention emerges as early as 8 to 10 months of age and is manifest when two social partners look back and forth between an object of interest and also look into the eyes of the social partner. They may also do so while pointing at the object or activity of interest (usually achieved by 14 to 16 months of age) or by bringing an object to show to the social partner . Finally, joint attention may be manifest when two social partners are having a conversation about a topic or activity of interest. The clearest example of joint attention occurs in the presence of all three of the above behaviors (shared eye gaze, pointing, and conversation). These behaviors can occur simultaneously or serially.
Children with ASD often have delayed or absent joint attention. They do not show, bring, or point out objects of interest to other people. They do not point to elicit shared interest , although they may point to obtain an object that they want. Young children with ASD may be content playing passively by themselves; they often are described by their caregivers as "good" infants and toddlers, undemanding of attention . They may or may not know how to identify or discuss a topic of shared interest.
Nonverbal and pragmatic communication behaviors
●Nonverbal communication – Individuals with ASD have impaired ability to use and interpret nonverbal (nonlinguistic) behaviors such as shared eye gaze, facial expression, intonation, gestures, body posture, and head and body orientation .
During interactions with the clinician, children with ASD may avoid eye contact, gaze too intently, or gaze at areas of the clinician's face or body other than the clinician's eyes . They may not change their facial expressions or may make exaggerated or "scripted" facial expressions. Children with ASD may have awkward or absent gestural communication. They may speak in a monotone voice that lacks emotional expressiveness.
Children with ASD may also fail to notice aspects of the nonverbal communication of others. For example, by not paying attention to the face, and in particular the direction of the social partner's eye gaze, they fail to understand the social partner's interest and/or the social partner's focus of attention. These nonverbal communication difficulties overlap with the examples of difficulty with social-emotional reciprocity indicated above. The individual with ASD may misinterpret or fail to understand gestures (eg, pointing, waving, nodding or shaking of the head) and facial expressions coming from the social partner.
●Pragmatic language – Pragmatic language refers to the skills needed to select the right words for the situation, so as to have the intended impact upon the listener. Pragmatic language skills include conventions such as taking turns in a conversation and maintaining some eye contact; contingency and topic maintenance (keeping the conversation on the same topic); adjusting the complexity of the language to suit the needs of the listener (eg, simplifying language for a younger audience; explaining terms that might not be familiar to the listener), and using nonverbal strategies such as changes in intonation, changes in facial expression, or gestures to modify the meaning of words or to convey emotion.
Impaired pragmatic language is a characteristic feature of ASD (with or without associated language impairment). (See 'Language impairment' below.)
Examples of the range of impaired pragmatic language skills in children with ASD include [1,24,30,31]:
•Not using language as a tool for communication (eg, simply repeating words [echolalia] or rote imitation of words or dialogue).
•Difficulty initiating or sustaining a conversation (eg, because of lack of turn-taking or because of an over-focus on personal interests).
•Difficulty producing a relevant response and maintaining the topic of conversation; this is sometimes associated with a lack of shared eye gaze and failure to interpret the conversation successfully.
•Failing to consider the interests, preference, or level of understanding of the listener; failing to explain a topic about which the listener may know nothing.
•Difficulty choosing the appropriate words or topics given the social context (eg, speaking too bluntly, not respecting the differences between familiar and nonfamiliar listeners, formal and informal contexts).
•Difficulty understanding the meaning of what is said (eg, providing responses that are unrelated to the topic of conversation).
•Not understanding how context or nonverbal communication may alter the meaning of words; this makes it difficult for persons with ASD to appreciate dual or ambiguous meanings, such as metaphors, humor, sarcasm, teasing, jokes, or deception (skills that are present in typically developing children by six to seven years of age) [32-34].
Although children with ASD can be taught to notice ambiguous meanings and social features of language, they generally do not master all of the subtleties and have difficulty applying their knowledge in real time. Once they have learned to notice nonverbal and pragmatic functions (eg, sarcasm or humor), they may use them inappropriately (eg, by inappropriately making sarcastic remarks to older peers or adults or by inappropriately attempting to make a joke), or they may misinterpret the comments of a peer as being sarcastic when they were not.
Developing and sustaining friendships
●Social cognition – Social cognition requires registering, remembering, synthesizing, and interpreting social information and language in a given context . It encompasses social attention and the use of nonverbal and pragmatic language skills – all of which are needed for successful socializing and for building friendships. Successful social cognition requires an individual to make multiple observations over a period of time, summarize and synthesize the information obtained from the observations, and then to infer the thoughts, feelings, and intentions of others.
Theory of mind is a term commonly used to describe social cognition, referring specifically to the ability to imagine or infer mental states. It includes imagining or knowing about the beliefs, desires, intentions, and emotions of others and the ability to guess at the actions that others are likely to take [36,37]. An individual with theory of mind skills is able to reflect on the content of their own and others' minds (eg, knowing that different people can hold different beliefs about the same thing or that different people may like and want different things). Some authors suggest that deficits in theory of mind are a crucial feature of ASD, given the preservation of nonsocial intelligence and other cognitive domains in some children with ASD [38,39].
Impaired social cognition is a core feature of ASD; it helps to differentiate ASD from other causes of impaired communication (table 2). (See "Autism spectrum disorder in children and adolescents: Evaluation and diagnosis", section on 'Differential diagnosis'.)
Examples of impaired social cognition include:
•Misunderstanding the emotional responses of others (eg, believing that someone is scared when they are happy, not understanding that someone is experiencing pain)
•Responding inappropriately to another's distress (eg, by laughing), which also may occur in children with other disabilities
•Not noticing that a social partner is not interested in their preferred topic of conversation
•Inability to understand the difference between acquaintances, friends, and intimate relationships
•Difficulty inferring the intentions, beliefs, attitudes, or likely behaviors of others
Although some children with ASD can interpret social information successfully in specific situations (eg, looking at photographs, reading a story), they may fail to recognize or successfully interpret the full range of social-emotional behaviors, especially in real time [40-42].
●Social interaction and relationships – Because of impairments in social-emotional reciprocity, nonverbal and pragmatic communication, and social cognition, individuals with ASD fail to form and maintain developmentally appropriate peer relationships.
Young children with ASD may have little or no interest in developing relationships. They may prefer solitary play to social play and may involve others only as tools or "mechanical" aids (ie, using the hand of a caregiver to obtain a desired object without making eye contact) . They may show delayed development of attachment to primary caregivers.
Few children with ASD are so socially isolated that they fail to interact with loved family members. However, social interactions with peers are usually limited in frequency and scope. Limited social interaction can be due to a limited motivation or interest in socializing. Caregivers of such children may describe them as independent rather than aloof and may be proud of their apparent self-sufficiency. Socializing may occur but without the expected joy and reciprocity seen in typical peers . Limited socializing can also occur in children who are motivated to socialize. Limited social success can be a significant source of distress for the child or adolescent with ASD, who is motivated to socialize but is not able to change social behaviors to get social needs met more successfully. Socially motivated children who fail to achieve satisfying peer relationships may develop depression or may be socially ostracized or bullied.
RESTRICTED AND REPETITIVE BEHAVIOR, INTERESTS, AND ACTIVITIES — The second core symptom of ASD is a pattern of restricted and repetitive behaviors, activities, and interests and hyper- or hyposensitivity to sensory input . These symptoms may continue throughout life and are especially obvious when they persist into school age. (See "Autism spectrum disorder in children and adolescents: Evaluation and diagnosis", section on 'Diagnostic criteria'.)
Stereotyped behaviors — Stereotyped and repetitive motor mannerisms or complex whole-body movements (eg, hand or finger flapping or twisting, rocking, swaying, dipping, walking on tip-toe [toe walking]) are a core symptom of ASD [44-47]. Children with ASD may line up an exact number of playthings in the same manner in a stereotyped ritual, without apparent awareness of what the toys represent [43,48]. Other stereotyped behaviors include delayed echolalia, such as repeating scripts or idiosyncratic phrases heard on video clips or from television programs or elsewhere .
Motor mannerisms are reported in 37 to 95 percent of individuals with ASD . Motor mannerisms often manifest during the preschool years. Stereotyped motor mannerisms appear to be self-stimulating and may also be self-injurious (eg, head-banging, face or body slapping, self-biting, or self-pinching) . Self-injurious behaviors are more common in ASD patients with severe intellectual disability. The triggers for stereotyped motor mannerisms or self-injurious behaviors may be predictable (eg, frustration, anxiety, excitement) or seemingly random. Self-injurious behavior may have a communicative intent (eg, attention, escape, avoidance) or may be internally driven. A new onset self-injurious behavior should prompt evaluation for an underlying cause (eg, pain, discomfort, infection).
Insistence on sameness/resistance to change — Insistence on sameness (cognitive rigidity) is another behavioral feature of ASD. It interferes with functional activities (eg, eating, communicating, socializing). Insistence on sameness may manifest with distress (eg, temper tantrums, anxiety) at small changes in routines and difficulty with transitions .
Examples of specific, nonfunctional routines or rituals that may occur during various aspects of daily life include:
●Always eating particular foods in a specific order
●Always following the same route from one place to another
●Always talking about the same things or repetitive questioning about a particular topic
●"Scripted" play activities (eg, mimicking verbatim what has been seen on television or in other types of media [eg, videos, websites])
●Not tolerating deviations from "normal" or "expected" rules of conduct
Some of these behaviors are similar to those in children with obsessive-compulsive disorder (OCD). However, unlike children with ASD, children with OCD typically have normal social communication and interaction. In addition, children with OCD who show rigid or obsessive behaviors commonly find them distressing, whereas those with ASD typically are unaware of their perseverations . Children with ASD may show more perseverative behaviors when they are anxious. The perseverative behaviors may give them a feeling of comfort or control, making it difficult to differentiate them from the child with OCD. (See "Autism spectrum disorder in children and adolescents: Evaluation and diagnosis", section on 'Differential diagnosis'.)
Restricted interests — Having restricted interests is another characteristic of ASD . Examples of restricted interests include:
●Encompassing preoccupation with ≥1 stereotyped or restricted pattern of interest that is abnormal in intensity or focus
Although many young children have restricted interests, the perseverative interests of children with ASD are more specific, unusual, and intense than those of typically developing children. Interest in mechanical topics, such as trains and cars, or topics from the natural sciences is common. Children with ASD have marked difficulty shifting their attention away from their preferred topic, even when provided with multiple cues, prompts, or requests. This contributes to impaired social interaction and difficulty completing chores, schoolwork, or daily tasks.
●Persistent preoccupation with unusual objects (eg, ceiling fans, vacuum cleaners)
The preoccupations of older children and those who are more cognitively able may include weather, dates, schedules, phone numbers, license plates, Thomas the Tank Engine, Pokémon, or subtypes of any classification (eg, dinosaurs, dogs, planes) [1,26].
Atypical responses to sensory stimuli — Atypical responses to sensory stimuli are common in children with ASD . They may be overresponsive, underresponsive, or have a paradoxical response to environmental stimuli (eg, noises, touch, odors, tastes, visual stimuli) . These atypical responses heighten their level of arousal and can contribute to inattention, anxiety, and/or problems with anger management.
Examples of atypical responses to sensory stimuli include [1,26]:
●Visual inspection of objects out of the corner of the eyes.
●Preoccupation with edges, spinning objects, or shiny surfaces, lights, or odors.
●Refusal to eat foods with certain tastes or textures or eating only foods with certain tastes and textures.
These behaviors may be associated with gastrointestinal symptoms (eg, weight abnormalities, diarrhea, constipation), which appear to be more prevalent in children with ASD than without ASD [52-56]. They also may be associated with nutritional deficiencies and selective eating [57-60].
●Preoccupation with sniffing or licking nonfood objects.
●Tactile defensiveness or resistance to being touched or increased sensitivity to certain kinds of touch; light touch may be experienced as painful, whereas deep pressure may provide a sense of calm. This may include resistance to the feel of certain clothing textures or colors next to the skin.
●Apparent indifference to pain.
●Strong preferences for and/or perseverative touching of certain textures and strong aversions to others.
●Hypersensitivity to certain frequencies or types of sound (eg, distant fire engines) with lack of response to sounds close-by or sounds that would startle other children.
ASSOCIATED CONDITIONS — ASD can be associated with other conditions, which are specified as part of the diagnosis .
Intellectual impairment — Cognitive skills of individuals with ASD are usually uneven, regardless of the general level of intelligence [1,61-63]. Performance on tasks that require rote, mechanical, visuospatial, or perceptual processes is usually better than on tasks that require higher-order conceptual processes, reasoning, interpretation, integration, or abstraction [61,64-66]. Intellectual disability is discussed separately. (See "Intellectual disability (ID) in children: Clinical features, evaluation, and diagnosis".)
Language impairment — Although language impairment is common in children with ASD, it is not necessary for the diagnosis. When language impairment is present, it should be specified as separate from the diagnosis of ASD . (See "Etiology of speech and language disorders in children" and "Evaluation and treatment of speech and language disorders in children".)
Consistent with the heterogeneity of other manifestations, there is a wide variability of the severity and quality of language dysfunction in children with ASD.
Among children with accompanying language impairment, the spectrum includes:
●Nonexistent communication (the child makes no attempts to share thoughts or interests or to make requests)
●Communication that consists only of a physical gestures (eg, takes an adult by the hand to lead them to a desired object or activity without accompanying eye contact or spoken language)
●Speaking only in single words or phrases
●Delayed language development
In children with ASD, receptive language may appear to be delayed relative to expressive language. Children may not respond to the calling of their names; concerns regarding hearing impairment may be the presenting complaint [18,67]. Their "better-developed" expressive language skills may represent nonfunctional language (eg, echolalia, rote/scripted language). In children with ASD, receptive language scores on formal assessment may be lower than those for expressive language. Because of their ability to remember language from movies or prior conversations, children with ASD can sometimes appear to have more sophisticated expressive language skills than can be supported by their receptive language. It is important to speak to children with ASD at their level of language comprehension rather than at their level of scripted or echolalic language production.
●Regression of language development
●Inability to understand simple questions or directions
●Atypical prosody (melody, tone, and inflection) or uneven pacing
●Language-based learning difficulties in reading comprehension, listening comprehension, oral expression, written expression, and applied math (word problems)
Children without accompanying language impairment (eg, those who can speak in grammatically correct sentences) have atypical pragmatic language, as described in the sections above. Children with ASD without accompanying language impairment may have behaviors and symptoms that overlap with a nonverbal learning disability (LD). Children categorized as having a nonverbal LD typically have stronger social skills than children with ASD (when language competence is the same) and clinically may present with a "desire" for friends but a lack of the skills to make them. (See 'Nonverbal and pragmatic communication behaviors' above and "Specific learning disorders in children: Clinical features", section on 'Nonverbal learning disorder'.)
Other neurodevelopmental conditions — ASD frequently co-occurs with other neurodevelopmental conditions or symptoms of neurodevelopmental conditions [68-74]. Symptoms of comorbid conditions (eg, anxiety, attention deficit hyperactivity disorder, disruptive behaviors, depression) may be exacerbated by negative social experiences and increased awareness of differences and social difficulties (eg, isolation, marginalization, and bullying) [75-77].
Neurodevelopmental conditions that are associated with ASD include [71-73,78-80]:
●Anxiety disorder – The rate of anxiety in ASD is significantly higher than in community samples, with the prevalence of anxiety disorders ranging from 42 to 55 percent and some degree of impairing anxiety ranging from 11 to 80 percent [76,81-83]; there persists some debate about whether or not anxiety is a core feature of ASD, a feature due to the impairments related to ASD, or a separate condition associated with autism [84,85]. (See "Anxiety disorders in children and adolescents: Epidemiology, pathogenesis, clinical manifestations, and course".)
●Attention deficit hyperactivity disorder (ADHD) – The comorbidity of ADHD and ASD is in the range of 30 to 50 percent [86-88]. (See "Attention deficit hyperactivity disorder in children and adolescents: Clinical features and diagnosis", section on 'Clinical features'.)
●Oppositional defiant disorder and other disruptive behavior disorders.
●Depression and other mood disorders (more common in adolescents and adults, particularly those without intellectual impairment) [83,89,90].
●Tic disorders. (See "Hyperkinetic movement disorders in children", section on 'Tic disorders'.)
●Learning difficulty – Children with ASD without intellectual disability may have learning difficulties despite performing well on standardized measures of educational achievement. They may begin to have difficulty in the third or fourth grade when limited pragmatic language skills and social awareness affect reading comprehension and written expression. Executive dysfunctions commonly also interfere with academic success at these and subsequent grade levels. Children with ASD and learning difficulties may become frustrated and develop problem behaviors if the learning difficulties are not recognized and addressed.
Examples of learning difficulties include:
•Poor performance in topics unrelated to their preferred interest
•Poor performance when group learning or classroom discussion is required
•Being easily overwhelmed if asked to manage their own schedule, keep track of their homework assignments, or complete complex assignments (eg, book reports, essays)
•Executive dysfunctions (eg difficulty remembering, planning, and completing tasks)
•Difficulty understanding abstract concepts that are part of a typical high school curriculum (eg, character development or motivation in works of fiction, historical or social concepts [eg, "peace," "justice," "liberty"])
•Nonverbal learning disability in children with ASD without an accompanying language impairment (a condition not recognized in Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision) (see "Specific learning disorders in children: Clinical features", section on 'Nonverbal learning disorder')
Sleep problems — Children with ASD may have associated sleep problems or disorders, including bedtime resistance, sleep anxiety, sleep-onset disturbances, frequent waking, restlessness, or abnormal sleep architecture [91-94]. (See "Behavioral sleep problems in children" and "Assessment of sleep disorders in children".)
Feeding problems — Given their atypical responses to sensory stimuli and need for routine, children with ASD may refuse to eat foods with certain textures or may eat only foods with certain tastes and textures. These behaviors may be associated with gastrointestinal symptoms (eg, weight abnormalities, diarrhea, constipation) or nutritional deficiencies due to atypical intake. (See 'Atypical responses to sensory stimuli' above.)
Medical or genetic conditions — ASD may be associated with medical conditions (eg, epilepsy), environmental factors (eg, valproate embryopathy), or genetic syndromes (table 3), which are discussed separately. (See "Autism spectrum disorder in children and adolescents: Terminology, epidemiology, and pathogenesis", section on 'Associated conditions and syndromes' and "Risks associated with epilepsy during pregnancy and the postpartum period".)
OTHER CLINICAL FEATURES
Motor deficits — Children with ASD may have motor deficits, including abnormal gait, clumsiness, toe walking, or other abnormal motor signs, such as hypotonia [1,95]. Although motor deficits are common [96,97], they are not defining features of ASD. (See "Autism spectrum disorder in children and adolescents: Evaluation and diagnosis", section on 'Diagnostic criteria'.)
Macrocephaly — Approximately one-fourth of children with isolated ASD have head circumference greater than the 97th percentile [98,99]. An increased rate of head growth is found in up to 70 percent of children with ASD during the first year of life, but not all of these children become macrocephalic [100-103].
Accelerated head growth may be related to abnormalities in the processes of early brain development that contribute to the clinical manifestations of ASD [100,104]. By two to four years of age, mean brain volume is increased and megalencephaly is present in some children [105,106]. However, in a longitudinal, nationally representative cohort of approximately 9000 children, the mean head circumference of children with and without ASD was similar at 9 months, 24 months, and 36 months . Thus, although macrocephaly occurs in some children with ASD, it is not required for the diagnosis.
Individuals with ASD and macrocephaly may have mutations in the PTEN gene, placing them at risk for hamartomatous tumor syndromes . Evaluation for PTEN hamartoma syndromes in children with ASD and macrocephaly is discussed separately. (See "PTEN hamartoma tumor syndromes, including Cowden syndrome", section on 'Autism spectrum disorders and macrocephaly'.)
Special skills — Some individuals have special skills (ie, "savant" skills) in memory, mathematics, music, art, or puzzles, despite profound deficiencies in other domains [26,43]. Other special skills include calendar calculation (determining the day of the week for a given date) and hyperlexia (spontaneous and precocious mastery of single-word reading) [109,110]. The reading is usually concrete, with little comprehension or understanding of the purpose of reading .
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Autism spectrum disorder".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient education" and the keyword[s] of interest.)
●Basics topic (see "Patient education: Autism spectrum disorder (The Basics)")
●Beyond the Basics topic (see "Patient education: Autism spectrum disorder (Beyond the Basics)")
●Phenotypic spectrum and clinical presentation – Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder that is characterized by abnormal social communication and social interaction, and restricted, repetitive patterns of behavior with a broad range of clinical manifestations. Symptoms usually are recognized in the second year of life but may be present earlier or manifest later when social demands exceed limited capacities. (See 'Phenotypic spectrum and clinical presentation' above.)
●Impaired social communication and interaction – Impaired social communication and interaction may manifest as (table 4A-B):
•Lack of social and emotional reciprocity (eg, lack of seeking to share enjoyment, interests, or achievement and impaired ability to demonstrate or respond to interest in interacting with others)
•Impaired use of nonverbal behaviors to regulate social interaction (eg, eye gaze, facial expression, gestures) and impaired pragmatic communication (eg, monopolizing a conversation without taking turns; difficulty understanding how the meaning of language changes with context; inability to understand humor or sarcasm)
•Failure to form and maintain developmentally appropriate peer relationships
(See 'Impaired social communication and interaction' above.)
●Restricted and repetitive behavior, interests, and activities – Behavioral features of ASD include restricted and repetitive behaviors, interests, and activities (eg, stereotyped and repetitive motor mannerisms, inflexible adherence to nonfunctional routines or rituals) and atypical responses to sensory stimuli (table 4A-B). (See 'Restricted and repetitive behavior, interests, and activities' above.)
●Associated conditions – ASD is often associated with intellectual impairment or language impairment. It also may be associated with other genetic, medical, or environmental factors. These associated conditions are specified as part of the diagnosis. (See 'Associated conditions' above.)
●Evaluation and diagnosis – The evaluation and diagnosis for children with clinical features of ASD are discussed separately. (See "Autism spectrum disorder in children and adolescents: Evaluation and diagnosis".)
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