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Understanding Autism Spectrum Disorder (ASD): An Introduction

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What is autism spectrum disorder (ASD)?

Autism spectrum disorder (ASD) is a neurologically based disability that affects a child’s social skills, communication, and behavior.

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. However, ASD symptoms may change as children get older and with intervention. While infrequent, some children improve so much that they might no longer be considered to have a diagnosis of ASD. Many of them, however, as they develop, will likely have other developmental, learning, language, or behavioral issues or diagnoses.

The sooner ASD is identified, the sooner an intervention program directed at the child’s symptoms can begin. Each child with ASD 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) services as soon as ASD symptoms are noted. The Early Intervention Program for Infants and Toddlers with Disabilities (also called “Part C”) helps each state offer EI services for infants and toddlers with disabilities, birth to 3 years of age, and their families. For more information and to find an EI program in your area, see the Resources section.

Aren’t there different types of ASD?

The symptoms that define ASD are described in a book called the Diagnostic and Statistical Manual of Mental Disorders (DSM). This manual lists definitions for behavioral, developmental, and psychiatric disorders. Several conditions used to be diagnosed separately under the term “pervasive developmental disorders” or “autism spectrum disorders.” Those conditions were autistic disorder, pervasive developmental disorder—not otherwise specified (PDD-NOS), and Asperger syndrome. With publication of the fifth edition of the DSM in May 2013, these terms are no longer used and these conditions are now grouped in the category of autism spectrum disorder or ASD.

How common is ASD?

ASD affects an estimated 1 out of every 68 children. The number of children reported to have ASD has increased since the early 1990s, and the increase could be caused by many factors. Many families are more aware of ASD. Pediatricians are doing more screening for ASD and children are identified earlier. Also, there have been changes in how ASD has 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. Boys are diagnosed with ASD about 5 times more often than girls.

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 with peers.

How might a child with ASD act?

One child with ASD will not have exactly the same symptoms as another child with ASD—the number and severity of symptoms can vary greatly. Here are examples of how a child with 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

What causes ASD?

Many factors may lead to symptoms of ASD. If a family already has a child diagnosed with ASD, the chance that a sibling might also have ASD is 10 to 20 times higher than in the general population. Environmental factors likely play a secondary role in some children with ASD, but what these factors are and how or when they affect development is not yet known. This is, however, an important area of research.

Studies have shown that relatives of children with ASD are more likely to have some similar social and behavioral characteristics to those seen in children with ASD but not be severe enough to merit a diagnosis. These difficulties may include social awkwardness, inflexibility and repetitive behaviors, and others. ASD may occur more often in children with certain medical conditions or high risk factors.

Medical conditions include fragile X syndrome, tuberous sclerosis complex, Down syndrome, or other genetic disorders. However, most children with ASD do not have these or any other specific genetic conditions. Babies born prematurely are another high-risk group. Considering whether a child with ASD has a genetic condition is an important part of the initial evaluation.

Is there a link between vaccines and ASD?

In the past, some individuals thought that vaccines were a cause of ASD. However, many studies have been done, and there is no scientifically proven link between childhood vaccinations — including the measles-mumps-rubella (MMR) vaccine — and ASD. In fact, the research article that first suggested a link between the MMR vaccine and ASD has been retracted (that is, removed permanently) because the research was done incorrectly. There also is no scientific proof to support a link between thimerosal (a mercury-containing preservative) and ASD. Even so, almost all vaccines given to children in the United States no longer contain mercury. The American Academy of Pediatrics urges parents to have their children fully immunized. Vaccines are a safe and effective way to protect children from diseases. Autism Speaks states that, “Vaccines do not cause autism. We urge that all children be fully vaccinated.” Families who remain concerned about vaccines and ASD should talk with their pediatrician.

How is the diagnosis made?

Diagnosis of ASD can be complicated for a number of reasons. There are no specific medical tests (for example, a blood test) to diagnose ASD, so primary care doctors must rely on information from families about the child’s development and behavior, 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 American Academy of Pediatrics (AAP) recommends that there be screening for ASD at specific well-child checkups (18- and 24-month visits) as well as ongoing surveillance in the course of well-child care. Talk with your doctor if you feel your child needs to be screened and share your concerns — you know your child the best.

Living with ASD

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.

Effective educational programs

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 year-round. Most 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.

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 community-based 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 or goals of the 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 some type of educational services and support and most may need therapy and behavioral intervention, only certain children will need medicine. Medicine may be used to help decrease behaviors that could interfere with making progress, such as learning or interaction with others, 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 ASD is identified, the sooner appropriate intervention programs can begin. While some 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. The goal of all parents is to help their child reach his full potential with the help of all available resources.



American Academy of Pediatrics. Autism Spectrum Disorders: What Every Parent Needs to Know. Rosenblatt AI, Carbone PS, eds. Elk Grove Village, IL: American Academy of Pediatrics; 2013

Attwood T. The Complete Guide to Asperger’s Syndrome. London, England: Jessica Kingsley Publishers; 2007

Baker J. Preparing for Life: The Complete Guide for Transitioning to Adulthood for those with Autism and Asperger’s Syndrome. Arlington, TX: Future Horizons; 2005

Bashe PR, Kirby BL. The OASIS Guide to Asperger Syndrome: Advice, Support, Insight, and Inspiration. Rev ed. New York, NY: Crown Publishers; 2005

Coplan J. Making Sense of Autistic Spectrum Disorders: Create the Brightest Future for Your Child With the Best Treatment Options. New York, NY: Bantam Books; 2010

Glasberg BA, LaRue RH. Functional Behavior Assessment for People with Autism: Making Sense of Seemingly Senseless Behavior. 2nd ed. Bethesda, MD: Woodbine House; 2015

Gray C. The New Social Story Book. Rev ed. Arlington, TX: Future Horizons; 2010

Harris SL, Weiss MJ. Right from the Start: Behavioral Intervention for Young Children with Autism. 2nd ed. Bethesda, MD: Woodbine House; 2007

Disorders. Rev ed. Troy, MI: QuirkRoberts Publishing; 2011

Kluth P, Shouse J. The Autism Checklist: A Practical Reference for Parents and Teachers. San Francisco, CA: Jossey-Bass; 2009

McClannahan LE, Krantz PJ. Activity Schedules for Children with Autism: Teaching Independent Behavior. 2nd ed. Bethesda, MD: Woodbine House; 2010

Moor J. Playing, Laughing and Learning with Children on the Autism Spectrum: A Practical Resource of Play Ideas for Parents and Carers. 2nd ed. London, England: Jessica Kingsley Publishers; 2008

Notbohm E. Ten Things Every Child with Autism Wishes You Knew. Rev ed. Arlington, TX: Future Horizons; 2012

Notbohm E, Zysik V. 1001 Great Ideas for Teaching & Raising Children with Autism or Asperger’s. 2nd ed. Rev ed. Arlington, TX: Future Horizons; 2010

Simpson RL. Autism Spectrum Disorders: Interventions and Treatments for Children and Youth. Thousand Oaks, CA: Corwin Press; 2005

Thompson T. Making Sense of Autism. Baltimore, MD: Paul H. Brookes Publishing Co; 2007

Volkmar FR, Wiesner LA. A Practical Guide to Autism: What Every Parent, Family Member, and Teacher Needs to Know. Hoboken, NJ: John Wiley & Sons; 2009

Wiseman ND. Could It Be Autism? A Parent’s Guide to the First Signs and Next Steps. New York, NY: Random House; 2006

Web sites

American Academy of Pediatrics (AAP Council on Children With Disabilities Autism Subcommittee) (official AAP Web site for parents)

Autism Science Foundation

Autism Speaks

Centers for Disease Control and Prevention

Early Childhood Technical Assistance Center (Early Intervention and Special Education)

Easter Seals

National Institute of Mental Health

Adapted from the AAP patient education booklet Understanding Autism Spectrum Disorder (ASD).

Developed by the American Academy of Pediatrics Council on Children With Disabilities Autism Subcommittee.

Listing of resources does not imply an endorsement by the American Academy of Pediatrics (AAP). The AAP is not responsible for the content of external resources. Information was current at the time of publication.

Products are mentioned for informational purposes only and do not imply an endorsement by the American Academy of Pediatrics.

The information contained in this publication 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.

Copyright © 2015 American Academy of Pediatrics. All rights reserved.

Additional Resources

The Federation for Children with Special Needs provides information, support, and assistance to parents of children with disabilities, their professional partners, and their communities. We are committed to listening to and learning from families, and encouraging full participation in community life by all people, especially those with disabilities.
Committed to supporting siblings of people with disabilities.
Pediatric Special Needs Resources for Massachusetts Families 
The Learning and Emotional Assessment Program (LEAP) at Massachusetts General Hospital assesses students and children ages 2 to 22 who have developmental difficulties and consults with their parents, teachers and care providers.

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