Autism Spectrum Disorder

Autism (AW-tis-ism) spectrum disorder is a diagnosis for a set of developmental disabilities that involve abnormal social interactions, poor or abnormal communication abilities, repetitive behaviors, and highly focused obsessive interest in a single topic. Before 2013, the disabilities now diagnosed as autism spectrum disorder were classified separately as autism, Asperger syndrome, childhood disintegrative disorder, and pervasive developmental disability not otherwise specified.

Thinking in Pictures

Temple Grandin, the gifted animal scientist, invented equipment for handling livestock, wrote books, and gave lectures. Yet as a child, Grandin had many of the signs of autism. As a baby, she stiffened when picked up and struggled to be put down. By the age of 2 years, she was sometimes overpowered by her ultrasharp senses. She screamed, flew into rages, and threw objects. At other times, she found that focusing intently on one object, such as an apple or her hand, made her feel calmer and safer.

Her mother put Grandin in a special class with strict routines designed for children with speech problems. By the age of 4 years, Grandin had started to speak, and by the age of 5 years, she could go to regular school. As an adult, she recalled her experiences in a book called Thinking in Pictures. The book begins: “I think in pictures. Words are like a second language to me.” Grandin used the way her brain worked to imagine how the parts of complicated equipment she invented fit together.

Jamie's Story

Until Jamie was about two years old, he appeared to be developing normally. However, around age two, he began to withdraw. He rarely spoke, and when he did, it was in single words. He often spent hours sitting on the carpet cranking an old non-electric eggbeater to make the paddles spin.

As he got older, Jamie withdrew even more, rarely looking at people or smiling. He resisted stopping whatever he was doing and moving on to a new activity. If his morning dressing ritual or evening bath ritual was changed even the least bit, he became very upset. His toys always had to be arranged in the “correct” order, or he would have a temper tantrum.

By age three, Jamie's parents knew something was seriously wrong. Although he physically looked normal, Jamie did not behave like most three-year-olds. His pediatrician asked Jamie's parents to complete an autism checklist. When it appeared that Jamie might be autistic, the pediatrician referred the family to a child psychiatrist who specialized in autism.

After a thorough examination, Jamie received a diagnosis of autism spectrum disorder (ASD). His family was referred to a highly structured behavioral early intervention program specifically for children with ASD. Here he and his parents learned how to moderate some of Jamie's behaviors and cope with the limitations of his disorder.

What Is Autism Spectrum Disorder?

Autism spectrum disorder (ASD) is a neurodevelopmental brain disorder that results in difficulties understanding emotions in others and communicating to such a degree that normal social interactions are seriously impaired. In addition, many people with ASD are obsessed with order and repetition. Some develop strange interests and abilities, such as memorizing train schedules or obsessing about motorcycle engines.

The word “spectrum” in the name of this disorder implies both a range of symptoms and a range of severities of the disorder that can vary considerably from person to person. Some children with severe ASD never learn to talk and may need to be prevented from repetitive activities that are harmful to them such as banging their head against the side of a crib or picking at their skin until it bleeds. Children with severe and moderate ASD are usually diagnosed in early childhood. Children with mild ASD may not be diagnosed until they enter school and deficits in social interactions and odd repetitive behaviors become more noticeable. It is not uncommon for people with ASD to have other mental health disorders such as attention deficit hyperactivity disorder (ADHD) and intellectual disabilities that may delay or confuse diagnosis.

With additional research, scientists found that these four disorders were quite similar and fell along a continuum of symptoms. The decision was made when the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) * was published to combine these diagnoses into ASD. Although people may still be referred to as having autism or Asperger syndrome, these are no longer formal diagnoses, and more and more people simply say that they are “on the spectrum,” meaning they have been diagnosed with ASD.

Boy taking part in an autism test that is analyzing his response to various facial expressions on a computer-generated face. People suffering from autism often have difficulty in judging the emotions reflected in different facial expressions.

Boy taking part in an autism test that is analyzing his response to various facial expressions on a computer-generated face. People suffering from autism often have difficulty in judging the emotions reflected in different facial expressions.
Annabella Bluesky/Science Source.

How Common is Autism Spectrum Disorder?

According to the U.S. Centers for Disease Control and Prevention Autism and Developmental Disabilities Monitoring Network, the diagnosis of ASD (or before 2013, the four related disorders) has increased in the United States from one in every 150 children under age eight in 2002 to one in every 68 children in 2010, the most recent year for which statistics were available. It is not clear how much of this increase is due to an increased awareness of the disorder and better diagnostic techniques and how much represents a true increase in the disorder. However, experts believe that some portion of the increase represents a true increase in the disorder as opposed to better reporting. Internationally, Korea and Japan have diagnosed ASD rates higher than the United States. ASD occurs in all racial and ethnic groups. However, boys with ASD outnumber girls by a little more than four to one (1 of every 42 boys vs. 1 of every 189 girls).

What Are the Signs of Autism Spectrum Disorder?

Signs of ASD fall into three categories: behaviors, communication deficits, and intellectual interests. Not every person with ASD shows all these signs to the same degree. Behavioral signs include:

Communication signs involve both verbal and nonverbal communication. These include:

Intellectual signs include:

In addition to these signs, it is not uncommon for people with ASD to show signs of intellectual disabilities or other mental health disorders.

What Causes Autism Spectrum Disorder?

Researchers are not sure what causes ASD, although they have some clues. Because the disorder is a spectrum disease with many symptoms and a range of severities, it is unlikely that there is a single cause. There is general agreement that multiple genes influence the development of ASD because children with a brother or sister who have ASD have a higher risk of developing the disorder. Also, some children who have chromosomal defects such as fragile X syndrome * are more likely to have ASD. Parental age also appears to be a factor. Children born to mothers over age 35 and fathers age 50 and older have an increased risk of having ASD.


Childhood disintegrative disorder (CDD) is a rare medical disorder that occurs in children usually after the first three years of life. Often referred to as Heller's syndrome, CDD may also be named disintegrative psychosis and social development regression. The progressively deteriorating condition is characterized by severely slowed mental development especially in the areas of cognitive skills (such as language), motor skills (such as walking), and social functions (such as interest in playing with other children). Often classified as a pervasive developmental disorder (PDD), there is no cure for CDD; however, medications and therapies help with symptoms.

Sometimes CDD is mistaken for autism. For this reason, the medical community generally considers autism to be a similar condition to CDD. But unlike autism, CDD is not present at birth and appears later. CDD may occur any time between 2 to 10 years of age.

Children with CDD generally have normal developmental skills until two years of age. Around this time, their ability to communicate, socialize, and perform other such skills begins to deteriorate and, in some cases, is totally lost.

Medications may help treat CDD, although there is no cure. Behavioral therapy may be used to help children relearn skills lost by the disease. Many children with CDD are left with permanent and serious disabilities that need long-term care.

How is Autism Spectrum Disorder Diagnosed?

All children should be screened for developmental disabilities at well-child visits to the pediatrician. If the pediatrician suspects a delay that may indicate ASD, parents and caregivers are usually asked to fill out an autism checklist. If ASD appears likely, the family is most often referred to a child psychiatrist who specializes in children with autism and who can recommend early intervention services for the child.

There are many tools like this picture exchange communication system that help the language skills of autistic children.

There are many tools like this picture exchange communication system that help the language skills of autistic children.
Adrian Sherratt/Alamy.

For a person to be diagnosed with ASD, he or she must lack both age-appropriate social and communication skills and show some form of repetitive behavior or age-inappropriate fixated interests. In addition, the diagnosing physician must indicate whether the deficit is severe (requiring a very substantial level of support), moderate (requiring substantial support), or mild (requiring some support). People with severe ASD often have minimal social behavior or communication and extreme problems coping with change. Those with moderate ASD may speak almost exclusively about their special interest and are rigid in routines with difficulty changing activities. People with mild ASD may have difficulty with social interactions and may have difficulty maintaining a normal back-and-forth conversation. They can be inflexible and have difficulty with planning and organization.

Since many people with ASD have other disabilities, extensive testing may be needed to rule out other physical and mental health problems as the cause of their symptoms. These tests can include brain scans and special blood tests.

How is Autism Spectrum Disorder Treated?

ASD is a lifelong disorder for which there is no cure. The goal of treatment is to teach social and communication skills and to reduce repetitive and disruptive behavior. Specific treatment depends on the severity of the disorder but can include speech therapy, occupational therapy, family therapy, and structured programs that use applied behavior analysis. There are various types of applied behavior analysis, and the technique chosen is based on the age and needs of the child.

No medications will treat ASD, but medications may be used to treat associated mental health disorders such as ADHD and physical disabilities. Many children with ASD have abnormal blood chemistries. Some of these children are helped by special diets that are directed at their specific chemical abnormality.

Can Autism Spectrum Disorder Be Prevented?

The cause of ASD is unknown, and the disorder cannot be prevented. The degree to which people with ASD can integrate successfully into society depends on the severity of their disorder, the level of professional and family support they receive, and the age at which intervention is begun. Those who begin structured programs very early in childhood generally have better outcomes than people with the same level of severity of ASD who begin treatment at an older age.

See also Attention Deficit Hyperactivity Disorder (ADHD) • German Measles (Rubella) • Intellectual Disability •


Books and Articles

Grossberg, Blythe. Asperger's Teens: Understanding High School for Students on the Autism Spectrum. Washington, DC: Magination Press, 2015.

Lawson, Wenn. Older Adults and Autism Spectrum Conditions: An Introduction and Guide. Philadelphia: Jessica Kingsley, 2015.

Prizant, Barry, and Tom Fields-Meyer. Uniquely Human: A Different Way of Seeing Autism. New York: Simon and Schuster, 2015.

Sicile-Kira, Chantal. Autism Spectrum Disorder (Revised): The Complete Guide to Understanding Autism. New York: Perigee Books, 2014.


Centers for Disease Control and Prevention (CDC). “Autism Spectrum Disorder (ASD).” (accessed March 22, 2016).

National Institute of Mental Health. “Autism Spectrum Disorder.” (accessed March 22, 2015).

National Institute of Neurological Disorders and Stroke. “Asperger Syndrome Fact Sheet.” Brain Resources and Information Network. (accessed September 23, 2015).


Autism Research Institute. 4182 Adams Ave., San Diego, CA 92116. Telephone: 619-281-7165. Website: (accessed March 22, 2016).

Autism Society of America. 4340 East-West Hwy., Suite 350, Bethesda, MD 20814-3067. Telephone: 800-3AUTISM. Website: (accessed March 22, 2016).

Autism Speaks. 1 E. 33rd St., 4th Floor, New York, NY 10016. Telephone: 888-288-4762. Website: (accessed March 22, 2016).

National Institute of Mental Health. 6001 Executive Blvd., Room 6200, MSC 9663, Bethesda, MD 20892-9662. Telephone: 866615-6464. Website: (accessed March 22, 2016).

* DSM-5 is the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, published by the American Psychiatric Association. This book is used by physicians in the United States to classify and diagnose mental conditions.

* fragile X syndrome is a mutation on the X chromosome that causes an inherited range of mental disability from mild to severe and also increases the risk of developing ASD.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)