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Autism Spectrum Disorder

​Autism spectrum disorder (ASD) is a brain-based disorder that affects a child's behavior, communication, and social skills. ​

Because most children with ASD will master early motor skills such as sitting, crawling, and walking on time, parents may not initially notice delays in social and communication skills. Looking back, many parents can recall early differences in interaction and communication.

ASD are developmental disorders whose symptoms may change with maturation and intervention. While infrequent, some children improve so much that they no longer can be considered to have an ASD. Most of these children will have other developmental, learning, language, or behavioral diagnoses.

The sooner an ASD is identified, the sooner an intervention program directed at core symptoms of autism can start. Each child with autism has different needs. The intervention that helps one child may not be as helpful for another. Research shows that starting an intervention program as soon as possible can improve outcomes for many children with ASD, so children can and should be referred for diagnosis and early intervention (EI) as soon as the ASD symptoms are noted.

How common is ASD?

ASD affects an estimated 1 out of every 68 children. This new estimate roughly represents a 30% increase from previous estimates reported in 2012 of 1 in 88 children being identified with ASD. The estimates reflect the findings of the report, “Prevalence of Autism Spectrum Disorder among Children Aged 8 Years – Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2010,” which was published on March 27, 2014 in the CDC’s Morbidity and Mortality Weekly Report.

The number of children reported to have ASD has increased since the early 1990s for unclear reasons. The increase could be caused by many factors. Many families are more aware of ASD. Pediatricians are doing more screening for ASD. Also, there have been changes in how ASD have been defined and diagnosed. In the past, only children with the most severe ASD symptoms were diagnosed. Now children with milder symptoms are being identified and referred to intervention and educational programs. ASD is almost five times more common among boys than girls: 1 in 42 boys versus 1 in 189 girls. White children are more likely to be identified as having ASD than are black or Hispanic children.

What are the symptoms of ASD?

No 2 children with ASD have exactly the same symptoms. There are standard criteria for the diagnosis of ASD. The following are examples of how a child with an ASD may act:

Social differences

  • Doesn't keep eye contact or makes very little eye contact
  • Doesn't respond to a parent's smile or other facial expressions
  • Doesn't look at objects or events a parent is looking at or pointing to
  • Doesn't point to objects or events to get a parent to look at them
  • Doesn't bring objects of personal interest to show to a parent
  • Doesn't often have appropriate facial expressions
  • Unable to perceive what others might be thinking or feeling by looking at their facial expressions
  • Doesn't show concern (empathy) for others
  • Unable to make friends or uninterested in making friends

Communication differences

  • Doesn't point at things to indicate needs or share things with others
  • Doesn't say single words by 16 months
  • Repeats exactly what others say without understanding the meaning (often called parroting or echoing)
  • Doesn't respond to name being called but does respond to other sounds (like a car horn or a cat's meow)
  • Refers to self as "you" and others as "I," and may mix up pronouns
  • Often doesn't seem to want to communicate
  • Doesn't start or can't continue a conversation
  • Doesn't use toys or other objects to represent people or real life in pretend play
  • May have a good rote memory, especially for numbers, letters, songs, TV jingles, or a specific topic
  • May lose language or other social milestones, usually between the ages of 15 and 24 months (often called regression)

Behavioral differences (repetitive and obsessive behaviors)

  • Rocks, spins, sways, twirls fingers, walks on toes for a long time, or flaps hands (stereotypic behavior)
  • Likes routines, order, and rituals; has difficulty with change
  • Obsessed with a few or unusual activities, doing them repeatedly during the day
  • Plays with parts of toys instead of the whole toy (for example, spinning the wheels of a toy truck)
  • Doesn't seem to feel pain
  • May be very sensitive or not sensitive at all to smells, sounds, lights, textures, and touch
  • Unusual use of vision or gaze—looks at objects from unusual angles

Are there different types of ASDs?

Not anymore. The symptoms that define autism are described in a book called the Diagnostic and Statistical Manual of Mental Disorders (DSM). In 2013, the American Psychiatric Association published the fifth edition—the DSM-5. The symptoms and behaviors that define a diagnosis of autism were modified in the new edition and the changes were based on a collection of new information gathered by experts since the last publication in 1994. The diagnosis is now Autism Spectrum Disorder (ASD). This means there are no longer different types (or subdiagnoses) that were called: Autistic Disorder, Asperger Syndrome, Pervasive Developmental Disorder Not Otherwise Specified, and Disintegrative Disorder.

What causes ASD?

Many factors may lead to symptoms of ASD. There is a genetic predisposition to ASD. This was initially determined by twin and other family studies. Although many chromosomal and gene abnormalities have been associated with symptoms of ASD, none of these are present in all affected children. If a family already has a child diagnosed with an ASD, the chances that siblings might also have some form of ASD are at least 5 to 10 times higher than in the general population. Environmental factors are likely to play a secondary role in some children with ASD, but what these agents are and when they affect development is not yet known.

Studies have shown that the relatives of children with autism are more likely to have some symptoms similar to those seen in children with ASD.

These difficulties may include:

ASD may occur more often in children with certain medical conditions, such as fragile X syndrome, tuberous sclerosis, Down syndrome, and other genetic disorders. Most children with ASDs do not have these or other specific genetic conditions. Symptoms of ASDs may be more common in babies born prematurely. Considering whether a child with an ASD has another genetic condition is an important part of the initial evaluation.

What are the early signs of ASD?

Many children with ASD may show developmental differences throughout their infancy, especially in social and language skills. Because they usually sit, crawl, and walk on time, more subtle differences in the development of gesture, pretend play, and social language often go unnoticed by families and doctors. In addition to delays in spoken language, families may notice differences in interaction and gesture.

Delay or lack of joint attention

One of the most important developmental differences between children with ASD and other children is a delay or lack of joint attention. Joint attention is looking back and forth between an object or event and another person and connecting with that person. It is a building block for later social and communication skills. Engaging in many back-and-forth social interactions, such as exchanging a lot of emotional expressions, sounds, and other gestures, is called reciprocal social interaction. Delays in joint attention skills are found in most children with ASD and rarely seen in children with other types of developmental problems. Thus, joint attention deficits are thought to be among the most characteristic deficits of ASD. There are several stages of joint attention. Children with ASD usually show delays or absent skills at every stage.

Subtle milestones in use and understanding of gestures occur at the following times:

  • At about 10 to 12 months of age, most typically developing children will immediately look in the direction of an object to which a parent is pointing. They will then look back at the parent and mimic the parent's expression, usually a smile. Children with ASD will often ignore the parent. This often causes parents to worry about their child's hearing.
  • Most children are able to point to out-of-reach objects that they want by 12 to 14 months. The child with an ASD may instead take a parent's hand and lead the parent to the object without making eye contact. Sometimes the child may even place the parent's hand on the object itself.
  • By 14 to 16 months of age, most children point at objects they find interesting. Children will look back and forth between an object and a parent to make sure that the parent is tuned in to what they are looking at. The child with an ASD only will point to an object because he wants the parent to get it for him, not because he wants the parent to enjoy looking at an object together.

Language delays

Almost all children with ASD show delays in nonverbal communication and spoken language. They may have words that they use to label things but never request things. They may have unusual words for their overall language level, such as saying letters or numbers when they do not yet have names they use for family members. Most young children go through a phase where they repeat what they hear. Children with ASD may repeat for a longer period and repeat movies or conversations with the tone of voice in which they heard them. Those children later diagnosed with Asperger syndrome will seem to have met language milestones during the toddler years, but use of language may be abnormal or overly sophisticated, or mature (little professors).

Regression in developmental milestones

About 25% of children will seem to have normal or near-normal development until about 18 months of age, after which they will gradually or suddenly stop using words they once had and become more withdrawn. Some families will recall subtle differences that might have been present prior to the regression, such as the child not turning to her name.

Is there a link between the MMR vaccine and ASD?

There has been a great deal of attention in the media around vaccines as a cause of autism. Current scientific evidence does not support a link between the measles-mumps-rubella (MMR) vaccine or any combination of vaccines and autism spectrum disorders (ASD). In fact, the original research article that suggested a link between the MMR vaccine and autism has been officially retracted (that is, removed permanently) because of serious flaws in how the research was conducted. There also is no scientific proof to support a link between thimerosal (a mercury containing preservative) and ASD. In any event, almost all vaccines in the recommended immunization schedules administered to children in the United States no longer contain mercury. Vaccines used for immunization of large numbers of people, like influenza vaccine, may still contain very small amounts of thimerosal. Families who remain concerned about this should discuss their concerns with their pediatrician.

How is the diagnosis made?

Diagnosis of ASD can be complicated for a number of reasons. There are no specific medical laboratory tests to diagnose an ASD, so doctors must rely on information from parents and on what can be observed during well-child checkups. The condition is complex, and symptoms are different for each child. This is why the AAP recommends that there be screening for ASD at specific well-child checkups as well as ongoing surveillance in the course of well-child care.


When an ASD is suspected as a cause of language and social delays, the child should be referred for both EI services and a full evaluation to determine if an ASD is the proper diagnosis. The evaluation may be done by a doctor or psychologist who has expertise in the diagnosis of ASD or, preferably, by a team of specialists that may include developmental pediatricians, child neurologists, child psychiatrists, psychologists, speech or language pathologists, occupational or physical therapists, educators, and social workers. Testing of developmental domains may occur through EI programs or the school system.

Typically, an evaluation will include the following:

  • Careful observation of play and child-caregiver interactions.
  • Detailed history and physical examination.
  • Developmental assessment of all skills (motor, language, social, self-help, cognitive). ASD is suspected when the child's social and language functioning are significantly more impaired than the overall level of motor, adaptive, and cognitive skills.
  • Hearing test. All children with any speech delays or those suspected of having ASD should have their hearing formally tested.
  • Language evaluation that provides standardized scores of expressive language (including speech) and receptive language, as well as an evaluation of pragmatic language (social use of language) and articulation (pronunciation).

Diagnosis of an ASD is made by applying DSM criteria using all the information collected by history, observation, and testing.

Medical tests

ASD may be associated with a known syndrome or medical condition. Newer, more sensitive tests have determined an underlying cause of an ASD in many more children than was previously thought. Laboratory tests may be indicated to rule out other possible medical conditions that could cause autism symptoms based on the child's history and physical examination. If indicated, the child may be referred to other specialists, such as a geneticist or a pediatric neurologist, to help diagnose medical conditions that might cause or be associated with symptoms of ASD.

  • Genetic tests. It is recommended that families be offered genetic testing, such as cytogenetic microarray testing. At present, up to 10% to 20% of children with ASD have abnormalities of their chromosomes identified using cytogenetic microarray testing. Fragile X syndrome may be present in up to 2% of boys with ASD, so fragile X testing should also be considered. Testing girls with ASD symptoms for Rett syndrome may be discussed depending on the child's history and physical examination. Genetic testing should be strongly considered if a child has atypical physical features or developmental delays, or if there is a family history of fragile X syndrome or intellectual disability (formerly known as mental retardation) of unknown cause. Other genetic tests may be needed in certain cases. Recommendations for genetic testing may change as new tests are developed.
  • Lead test. Lead screening is an important component of primary care. A lead level should be performed when a child lives in a high-risk environment, such as older buildings, or continues to put things in his mouth.
  • Other tests. Based on the child's medical history and physical examination, an electroencephalogram (EEG), a magnetic resonance imaging (MRI) scan, or tests for metabolic disorders may be ordered. Children with ASD may be picky eaters, so your child's pediatrician may recommend looking for evidence of iron or vitamin deficiencies (especially vitamin D).

Note: There is not enough clinical evidence to recommend any of the following tests specifically for autism: hair analysis, routine measurement of multiple vitamin or nutrient levels, intestinal permeability studies, stool analysis, urinary peptides, or measurement of mercury or other heavy metals.

Living with ASDs

There are many different strategies and techniques to help children with ASD learn to interact with others and acquire new skills that may help them talk, play, participate in school, and care for their needs.

According to an expert panel writing for the National Academy of Sciences, effective educational programs designed for children with ASD from birth to 8 years of age should:

  • Offer choices. The program should offer a variety of behavioral, language, social, play, and cognitive strategies that are individualized to the child. If possible, the child should also receive direct speech, occupational, and physical therapies according to individual need.
  • Have clear goals. An individualized plan should include specific, observable, and measurable goals and objectives in each developmental and behavioral area of intervention.
  • Be intense. The program should be intense, with a goal of 20 to 25 hours of planned intervention or instruction per week. It should be given yearround. The majority of children benefit from a staffing ratio of 1:1 or 1:2 with an adult in initial interventions.
  • Encourage parents to be fully involved. Siblings and peers should also be included in the program. Children often learn best by modeling typically developing children in inclusive settings. The family should have support from the therapy team so it can promote social skills, functional communication, and appropriate behavior at home.
  • Take place in everyday settings. To promote generalization of newly acquired skills, interventions should take place in everyday settings. Playing and learning with children without ASD may help children with ASD learn social and language skills.
  • Address behavior problems. A functional analysis of behavior should be done when there are behavior problems. Information gained should be used to design a behavior management plan. The family should be involved so it can work on the child's behavioral needs too.
  • Monitor progress often. If goals and objectives are not being met in a reasonable amount of time, the program should be evaluated and revised as needed.

The types and quality of services may vary depending on where a family lives. Efforts are being made nationally to increase funding and training, so professionals can meet the needs of children with ASD in medical and educational settings. While resources vary among communities, a combination of parent and professional interventions can improve the development of children with ASD.

Children should be referred to an appropriate program as soon as a delay is suspected. Parents should not wait for a definitive diagnosis of ASD because this may take quite some time. For example, speech therapy evaluation and treatment should be started as soon as a communication delay is identified. Once ASD or another developmental disability is definitively diagnosed, the specific program can be changed to best meet the needs of the child and family. Keep in mind that diagnosis can be an ongoing process as additional signs and symptoms become noticeable or others improve.

Although all children with ASD will need educational services and most will need therapy and behavioral interventions, only certain children may need medicine. Medicine may be used to help decrease behaviors that could interfere with learning or interaction with others, such as aggression, obsessions, or hyperactivity.

Parents are encouraged to learn as much as they can about all the different treatments available. Treatment should focus on supporting the child to succeed in the real world.

The future

Children with ASD are affected by many factors that will shape their future. Overall, the long-term outcomes of children with ASD have been improving. In general, the sooner an ASD is identified, the sooner appropriate intervention programs can begin. While we believe that children make significant developmental gains with early and intense intervention, some children may make slow progress depending on their intelligence, the severity of their ASD symptoms, and whether they have associated medical problems such as seizures or significant behavioral disorders.

Children with intelligence in the typical range and milder symptoms of ASD are more likely to complete academic programs at school and have greater success in community employment as adults.

The goal of all parents, whether their child is typical or has a disability, is to help their child reach his full potential with the help of all available resources.

Last Updated
Adapted from Understanding Autism Spectrum Disorders (ASDs): An Introduction (Copyright © 2012 American Academy of Pediatrics)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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