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Patient education: Autism spectrum disorder (Beyond the Basics)

Marilyn Augustyn, MD
Section Editors
Marc C Patterson, MD, FRACP
Carolyn Bridgemohan, MD
Deputy Editor
Mary M Torchia, MD
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Autism spectrum disorder (ASD) is a developmental disorder that causes lifelong difficulties with socializing, communicating, and behavior. The term "spectrum" refers to the fact that some people have a few mild symptoms while others have severe symptoms that are disabling.

In May 2013, the criteria used to diagnose ASD and the names of some types of ASD changed. Children who used to be diagnosed with a particular type of autism (eg, Asperger syndrome) are now given the diagnosis of "ASD." ASD is then classified according to the level of severity and degree of support needed for the two core symptoms (problems with social communication and restricted and repetitive behaviors).

This topic will discuss general information about ASD.

How does autism spectrum disorder develop? — It is not clear how or why ASD develops. The general consensus is that ASD is a neurodevelopmental disorder that affects brain development and impairs the development of social and communication skills. This, in turn, leads to the typical symptoms of ASD. (See 'Symptoms of autism spectrum disorder' below.)

Environmental factors such as toxic exposures before or after birth, complications during delivery, and infections before birth may be responsible for a small percentage of cases. In children with a genetic predisposition, environmental factors may further increase the child's risk of developing ASD.

Some authors have attributed ASD to vaccine exposure (particularly measles vaccine and thimerosal, a mercury preservative used in vaccines). However, the overwhelming majority of scientific studies do not support an association between immunizations and ASD. (See "Patient education: Why does my child need vaccines? (Beyond the Basics)".)

How common is autism spectrum disorder? — The number of children diagnosed with ASD in the United States and other countries has increased since the 1970s and particularly since the late 1990s. It is not clear if the increase is related to changes in the criteria used to diagnose ASD or if the condition has become more common over time. Most experts agree that increased awareness of ASD and changes in the definition of ASD account for much of the apparent increase in the prevalence of ASD.

Between 2 and 20 children per 1000 have ASD, and it affects more boys than girls (approximately four boys for every one girl). Approximately 4 to 7 percent of siblings of children with ASD also have the condition, but the risk may be higher.

Medical conditions associated with autism spectrum disorder — There are a number of medical conditions associated with ASD.

Between 45 and 60 percent of children with ASD are intellectually disabled (previously called mentally retarded).

Between 11 and 39 percent of children with ASD have seizures. The risk of seizures is higher in individuals with more severe intellectual disability (mental retardation). (See "Patient education: Seizures in children (Beyond the Basics)".)

A minority (fewer than 10 to 25 percent) of cases of ASD are associated with a medical condition or syndrome, such as tuberous sclerosus, fragile X syndrome, Rett syndrome, phenylketonuria, fetal alcohol syndrome, or Angelman syndrome.


Symptoms of autism spectrum disorder (ASD) are usually recognized between two and three years of age, although they may be present earlier. By definition, symptoms must be present in early development, but sometimes the symptoms are not apparent until the child is older. Symptoms cluster into two broad areas: 1) social communication and 2) restricted and repetitive behavior, activities, and interests.

In approximately two-thirds of children with ASD, the first sign is a lack of communication skills by two years of age. Reasons for parents to seek help are discussed below. (See 'When to seek help' below.)

Social interaction and communication — Problems with social interaction and communication are the most common concern of parents, which often leads the parent to seek medical attention. The child may lack the ability to speak or understand and/or may show no interest in communicating.

Social interaction — Difficulty with or lack of interaction with family and friends is a hallmark of ASD. Components of social interaction include nonverbal behaviors, peer relationships, joint attention, and social reciprocity (which are explained below).

Individuals with ASD often have a hard time learning to interact with other people. Younger children may have little or no interest in developing friendships. They may prefer to play alone rather than playing with others, and may involve others in activities only as tools or "mechanical" aids (ie, using the hand of a parent to obtain a desired object without making eye contact).

Older children may become more interested in talking or socializing with other people but may not understand social conventions or the needs of others. As an example, the child may continue talking about a topic of their own interest with complete disregard for the interests of the listener.

Individuals with ASD are not interested in sharing activities, interests, or achievements; this is referred to as impaired joint attention. Joint attention is a normal behavior in which an infant or toddler tries to share interest, amusement, or fear with a caretaker. The child does this by purposefully looking back and forth between an object and the eyes of the caretaker (usually by 8 to 10 months of age) or by pointing to the object (usually by 14 to 16 months of age). Older children with ASD may not show or bring an object to the caretaker.

Individuals with ASD are sometimes not able to share a pleasurable activity with others. As an example, the child may prefer to play alone amidst a crowd of children engaged in the same activity.

Nonverbal behaviors — Individuals with ASD have difficulty using and interpreting nonverbal behaviors such as eye contact, facial expression, gestures, and body postures. For example, a child may not be able to understand the facial expressions associated with anger or annoyance.

During infancy, parents may notice that the baby resists cuddling, avoids eye contact, or does not spread the arms in anticipation of being picked up; however, these behaviors are not universal.

Restricted and repetitive behavior, activities, and interests

Stereotyped behaviors — Another behavioral feature of ASD is repetitive body movements, such as hand or finger flapping or twisting, rocking, swaying, dipping, or walking on tip-toe. These behaviors are seen in 37 to 95 percent of individuals with ASD and commonly begin during the preschool years. These behaviors are often lifelong.

Insistence on sameness — Many children with ASD have specific routines or rituals that must be followed exactly. These may occur as a part of daily life, such as the need to always eat particular foods in a specific order or to follow the same route from one place to another without deviation. Changes in routine can be upsetting or frustrating, even causing the child to have a tantrum or meltdown.

Restricted interests — Younger children may be preoccupied with peculiar sensory objects or experiences, such as spinning objects, shiny surfaces, the edge of objects, lights, odors, or sniffing or licking nonfood objects.

Older children may be preoccupied with the weather, dates, schedules, phone numbers, license plates, cartoon characters, or other items (eg, dinosaurs, dogs, planes).

Sensory perception — Many people with ASD perceive sounds, tastes, or touch differently. For example, the person may be overly sensitive to normal noise levels or have no response to loud noises.

Other examples include:

Refusal to eat foods with certain tastes or textures, or eating only foods with certain tastes and textures. These dietary obsessions can cause gastrointestinal symptoms, such as weight loss, diarrhea, or constipation.

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.

Hypersensitivity to certain frequencies or types of sound (eg, distant fire engines) and lack of response to sounds close by or sounds that would startle other children (eg, firecrackers).

Other features

Cognitive skills — Cognitive skills include the ability to think, remember, and process information. In children with ASD, these skills are often uneven, regardless of the child's level of intelligence. The person can often perform tasks that require memorization or putting things together (eg, puzzles), but may have difficulty with tasks that require higher-level skills, such as reasoning, interpretation, or abstract thinking.

Some individuals have special skills (ie, "savant" skills) in memory, mathematics, music, art, or puzzles, despite significant difficulties in other areas. Other special skills can include calendar calculation (determining the day of the week for a given date) and hyperlexia (the ability to read written words that are far above the person's reading level). However, the person may not understand what is being read or the purpose of reading.

Language skills — A delayed or absent ability to speak may be a feature of ASD. Unlike children with a hearing impairment, children with ASD do not try to compensate for their lack of speech by using alternate means of communication, like gesturing or miming. In most individuals with ASD, the ability to understand is delayed even more than the ability to speak. Children may not respond to their name, and the parent may initially be concerned that the child has a hearing problem. A child may not be able to understand simple questions or directions.

There is wide variability in the severity and quality of language problems in children with ASD. The ability to speak never develops in approximately one-half of affected children. In others, the child is able to speak, but language is not used as a tool for communication (eg, it consists of repeating phrases or words spoken by others, called echolalia).

Those who are able to speak may have difficulty starting or sustaining a conversation with others. Their language may have meaning only to people who are familiar with the autistic individual's communication style.

Large head — Approximately one-fourth of children with ASD have a larger-than-normal-size head. The medical term for this is macrocephaly. This may be related to abnormalities in early brain development, which contribute to the signs and symptoms of ASD discussed above.


If a child has symptoms of autism spectrum disorder (ASD), he or she is usually evaluated by a team that has expertise in diagnosing and managing the condition. This team often includes a child psychologist, developmental-behavioral pediatrician, neurologist, psychiatrist, speech therapist, and other professionals.

The evaluation usually includes a complete medical history (of the child and family), physical examination, neurologic examination, and testing of the child's social, language, and cognitive skills. In addition, the parent(s) will have time to discuss the child's behavior and any other concerns.

The purpose of the evaluation includes the following:

Determine if the child has ASD or if another condition could be causing the child's symptoms

Determine if the child has any ASD-associated medical problems that should be evaluated or treated

Determine the child's strengths, weaknesses, and level of functioning


Some common symptoms of autism spectrum disorder (ASD) are listed in the table (table 1).

Parents who notice that their child has one or more symptoms of ASD should talk to the child's health care provider. The provider should screen the child for ASD.

If the provider's evaluation raises red flags for ASD, the child should be referred for a complete evaluation for ASD. Early diagnosis and treatment of ASD can modify some behaviors consistent with ASD and improve socialization. (See 'Autism spectrum disorder diagnosis' above.)

Even before the complete evaluation, the child should be referred for a hearing test (if not done previously) and for early intervention services. Early intervention is a support and treatment system that provides appropriate therapies for children with disabilities. It can help to minimize delays and maximize the child's chance of reaching normal milestones in development. Even if the child is not diagnosed with ASD, early intervention services can help to address parents' concerns (eg, delayed language skills, temper tantrums).


Autism spectrum disorder (ASD) cannot be cured. However, a health care provider can work with parents to develop a treatment plan to help the child reach his or her full potential. The optimal treatment plan depends upon the child's age, diagnosis, underlying medical problems, and other individual factors.

The American Academy of Pediatrics recommends a plan that provides structure, direction, and organization for the child [1]. In the United States, services are often provided through an early intervention program and then subsequently through the public school system after the age of three years, administered by the individual states. Information about services for children with ASD is available through the Center for Parent Information and Resources.

Other resources for parents and providers are listed below. (See 'Where to get more information' below.)


Your child's health care provider is the best source of information for questions and concerns related to your child's medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient-level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces 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.

Patient education: Autism spectrum disorder (The Basics)
Patient education: Asperger syndrome (The Basics)
Patient education: Learning disabilities (The Basics)
Patient education: Fragile X syndrome (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Why does my child need vaccines? (Beyond the Basics)
Patient education: Seizures in children (Beyond the Basics)

Professional-level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Autism spectrum disorder and chronic disease: No evidence for vaccines or thimerosal as a contributing factor
Autism spectrum disorder: Clinical features
Autism spectrum disorder: Diagnosis
Autism spectrum disorder: Screening tools
Autism spectrum disorder: Surveillance and screening in primary care
Autism spectrum disorder: Terminology, epidemiology, and pathogenesis

The following organizations also provide reliable health information.

National Institute of Mental Health


Medline Plus

(www.nlm.nih.gov/medlineplus/autism.html, available in Spanish)

National Institute of Neurological Disorders and Stroke


United States Center for Disease Control and Prevention


Autism Speaks


Autism Society of America


The Autism Navigator, an online collection of resources including videos of children with early signs of ASD (available for free with registration)


Learn the Signs. Act Early.


The United Kingdom's National Autistic Society


Federation for Children with Special Needs


Asperger/Autism Network



Literature review current through: Nov 2017. | This topic last updated: Thu Sep 21 00:00:00 GMT+00:00 2017.
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  1. Myers SM, Johnson CP, American Academy of Pediatrics Council on Children With Disabilities. Management of children with autism spectrum disorders. Pediatrics 2007; 120:1162.
  2. Johnson CP, Myers SM, American Academy of Pediatrics Council on Children With Disabilities. Identification and evaluation of children with autism spectrum disorders. Pediatrics 2007; 120:1183.
  3. National Institute for Health and Clinical Excellence. Autism diagnosis in children and young people: Recognition, referral and diagnosis of children and young people on the autism spectrum http://publications.nice.org.uk/autism-diagnosis-in-children-and-young-people-cg128 (Accessed on June 25, 2013).
  4. American Psychiatric Association. Autism spectrum disorder. In: Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, American Psychiatric Association, Arlington, VA 2013. p.50.
  5. Christensen DL, Baio J, Van Naarden Braun K, et al. Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years--Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2012. MMWR Surveill Summ 2016; 65:1.

All topics are updated as new information becomes available. Our peer review process typically takes one to six weeks depending on the issue.