Autism Spectrum Disorder


Autism spectrum disorder (ASD) is a complex developmental disorder distinguished by difficulties with social interaction, verbal and nonverbal communication, and behavioral problems, including repetitive behaviors and narrow focus of interest.


The diagnostic criteria of autism disorders were re-evaluated by the American Psychiatric Association in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) published in 2014. The fourth edition had listed as separate disorders autistic disorder (ASD), Asperger's disorder, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified. In the fifth edition, all autistic disorders were grouped under the category of autism spectrum disorder with a diagnosis that indicates the severity of impairment and specifics of the type of behaviors present. In conversation, people often refer to individuals with an ASD diagnosis simply as having autism or being on the spectrum.

ASD usually manifests before a child is three years old, and it continues throughout the individual's life. The severity of the condition varies among individuals, ranging from the most severe (extremely unusual, repetitive, self-injurious, and aggressive behavior) to very mild. Autistic children vary greatly in the symptoms they show, so treatment options must be devised to treat each autistic child individually. ASD cannot be cured, but its symptoms can be modified. With early diagnosis and intensive therapy, autistic children may be able to lead healthy, full lives.

Prevalence of Autism Spectrum Disorders

SOURCE: Centers for Disease Control and Prevention, “Autism Spectrum Disorders (ASDs): Data & Statistics.” Available online at: (accessed May 8, 2018).

Risk factors

There appears to be a partial genetic basis for ASD. Family studies have shown that identical twins are more likely to both be diagnosed with ASD than twins who are fraternal (not genetically identical). In a family with one autistic child, the chance of having another child with ASD is about one in 20 or approximately 5%, much higher than in the general population.

Other risk factors that appear to be associated with ASD are:


As of 2018, the Centers for Disease Control (CDC) estimates that about one in every 68 children in the United States is affected by ASD, nearly twice the rate in 2004. ASD is four times more likely to be diagnosed in males. ASD is a disorder that is found worldwide. In the United Kingdom, one out of every 100 children has ASD, with about 700,000 total diagnosed as of 2018. Studies conducted in Asia, Europe, and North America report a prevalence rate of approximately 1%. ASD is not specific to any one socio-economic, ethnic, or racial group.

Causes and symptoms

Researchers know that ASD is a complex brain disorder that affects the way the brain uses or transmits information. Studies have implicated several causes for the disorder, including genetic errors and possible environmental triggers, that potentially change the expression of genes while in embryonic development, leading to ASD. As of 2018, more investigation was needed to determine the role of epigenetics in ASD development. Studies have found abnormalities in several parts of the brain that are believed to have occurred during fetal development. The problem may be centered in the parts of the brain responsible for processing language and information from the senses.

Profound problems with social interaction are the most common symptoms of ASD and the most visible. Autistic children have different ways of learning and experiencing the world around them. Often autistic children have more acute reactions to sensory stimulation such as sound and touch. This reactivity results in avoidance of eye contact, physical contact, and often an aversion to music and other sounds. It is perhaps the way autistic children experience their world that causes difficulties with social interaction, language, and nonverbal communication.

Human beings are social creatures, and social interaction is present from birth onward. Children with ASD have difficulty making social connections. A developmental milestone is when infants can follow an object or person with their gaze. Autistic children tend to avoid eye contact altogether even as infants.

Major brain structures implicated in autism

Major brain structures implicated in autism

They do not actively cuddle or hug but rather they passively accept physical contact, or they shy away from it. They may become rigid or flaccid when they are held, cry when picked up, and show little interest in human contact. Such children do not lift their arms in anticipation of being picked up. They may appear to have formed no attachment to their parents or caregivers and do not learn typical childhood games, such as peek-a-boo.

Autistic children do not readily learn social cues. They do not know when or how to react appropriately to specific social situations or exchanges. Because of this pattern, autistic children tend to look at and respond to a variety of different situations similarly. They do not understand that others have different perspectives; therefore, autistic children seem to lack empathy.

Because of their social problems and the inability to translate social interactions appropriately, autistic children seem to have uncontrolled emotional outbursts, expressing themselves in a manner that does not suit the specific social situation of the moment.

Language problems

Verbal communication problems vary greatly for autistic children. Some children do not speak at all.

Some will only use one or two words at a time. Some autistic children may develop vocabulary only to lose it. Other autistic children may develop an extensive vocabulary; however, they have difficulty sustaining an appropriate, natural, conversational exchange. Autistic children tend to talk in a sing-song voice or more robotically without emotional inflections. Often children with autism do not take body language into consideration, and they take what is being said quite literally. Because of their impinged language skills and the inability to express their needs, these children seem to act inappropriately to get what they need. They may grab something without asking or blurt out statements.

Restricted interests and activity

Language and social problems inhibit social play for children with autism. They do not engage in imaginative play and role playing. They focus on repetition, some fixating intensely on a subject of interest.

Autistic children often stick to a rigid daily routine. Any variance to the routine may be upsetting to them and result in an extreme emotional response. Repetitive physical behaviors such as rocking, spinning, and arm flapping are also characteristic of ASD. The repetitive behaviors are often self-soothing responses to sensory stimulation from their environment.

Sensory problems

The sensory world poses problems to many children with autism, who seem overwhelmed by their own perception of the world around them. Children with ASD may ignore objects or become obsessed with them, continually watching one object or the movement of their fingers over it. Some children with ASD react to sounds by banging their head or flapping their fingers. Some high-functioning autistic adults who have written books about their childhood experiences report that sounds were often excruciating to them, forcing them to withdraw from their environment or try to cope by withdrawing into their own world of sensation and movement.


There are no medical tests for diagnosing ASD, although tests may be done to rule out other disorders. Diagnosis is made after careful observation and screening by parents, caregivers, and physicians. Early diagnosis is beneficial in treating the symptoms of ASD. Some early warning signs are:

Once parents feel there is a problem or their pediatrician has identified developmental problems during well-baby check-ups, they can seek a developmental pediatrician for further diagnosis. There are several screening tests used. They are:

Some children have a few symptoms of ASD, but not enough to be diagnosed with the classical form of the condition. Children who have autistic behavior but no problems with language were formerly diagnosed with Asperger syndrome. Under the new diagnostic code, they would be diagnosed as having ASD with the type of impairment(s) present and the level of support needed specified as part of the diagnosis.


The earlier treatment begins, the better the chance of modifying symptoms and increasing social functioning. Because the symptoms of ASD can vary greatly, treatment must be individualized. A spectrum of interventions, including behavioral and educational training, diet and nutrition, alternative medicine and therapies, and medication can be fine tuned to treat individuals. The most strongly recommended treatment option is behavioral and educational training. Early intervention and treatment are essential for helping children with autism grow into productive adults. Some studies suggest that the individual's level of functioning generally correlates with the child's IQ.

Educational and behavioral treatment

Educational and behavioral treatments include the following:

Typically, behavioral techniques are used to help these children respond and to decrease symptoms. This can include positive reinforcement to boost language and social skills. Training includes structured, skill-oriented instruction designed to improve social and language abilities. Training needs to begin as early as possible, since early intervention appears to influence brain development positively.

Many autistic children respond to intervention at home as well as at school. Schools focus on areas in which these children may be delayed, such as in speech or socialization. As autistic children grow and move to different phases of childhood and adolescence, parents in collaboration with educators and physicians need to adapt the treatment to best suit the needs of their autistic child.


No single medication treats symptoms of ASD; however, some medications have been used to combat specific needs in autistic children. Drugs can control epilepsy, which affects up to 20% of people with ASD. Medication can also treat anxiety, depression, and hyperactivity. Medication must be individualized and adjusted as the child develops.

Drugs are prescribed to treat conditions associated with ASD such as anxiety or depression. Although prescriptions must be individualized based on the symptoms of the individual, four types of drugs are sometimes prescribed to help the behavior problems. These are:

Alternative and complementary treatment

Alternative treatments are those used instead of traditional medical treatments pharmaceutical drugs. Complementary treatments are used in addition to traditional medical treatments and pharmaceutical drugs. No alternative or complementary treatments cure ASD, but some individuals are helped with changes in diet and dietary supplements. Nevertheless, as of 2018 few studies had been done to pinpoint appropriate dosages and to assure safety of supplements.

A type of medication that is used to treat depression; it is also sometimes used to treat ASD.
A measurable substance that is present in the body that indicates abnormal biological process or the presence of a disease, disorder, or exposure to a toxic substance.
Fragile X syndrome—
A genetic condition related to the X chromosome that affects mental, physical and sensory development.
Major tranquilizers—
The family of drugs that includes the psychotropic or neuroleptic drugs, sometimes used to help autistic people. They carry significant risk of side effects, including Parkinsonism and movement disorders, and should be prescribed with caution.
A class of drugs, including Ritalin, sometimes used to treat people with ASD. They may make children calmer and better able to concentrate, but they also may limit growth or have other side effects.
Tuberous sclerosis—
A genetic disease that causes skin problems, seizures, and mental retardation. ASD occurs more often in individuals with tuberous sclerosis.
Vitamin and mineral therapy

Some parents report success with megavitamin therapy. Some studies have shown that vitamin B6 with magnesium improves eye contact and speech and lessens tantrum behavior. Vitamin B6 causes fewer side effects than other medications and is considered safe when used in appropriate doses. However, few health practitioners advocate its use in the treatment of ASD, citing that the studies showing its benefit were flawed.

DMG (dimethylglycine) Diet

Many parents have seen beneficial effects from a gluten-free and casein-free diet. Gluten is a substance found in the seeds of cereal plants such as wheat, barley, and rye. Casein is a protein found in milk. Often people have sensitivities to these substances without realizing it. Many foods contain these substances as an ingredient; however, there are growing numbers of gluten-free and casein-free foods available for people that would like to eliminate them from their diets. Parents interested in using diet as a treatment should discuss with their child's doctor how to initiate an elimination diet.


One researcher found that vigorous exercise (20 minutes or longer, three or four days a week) seems to decrease hyperactivity, aggression, self-injury, and other autistic symptoms.

Public health role and response

A study partially funded by Autism Speaks found that in 2015, autism cost the American economy $265 billion. As such, ASD has a significant impact on public health, and as of 2018 solutions were being actively sought.

In 2008, Autism Speaks initiated the Global Autism Public Health (GAPH) Initiative. The program is an integrated approach that focuses on three goals to improve the health and well-being of children and families affected by ASD. These goals are:


ASD is treatable but not curable. With appropriate treatments adjusted to suit individual children with autism, these individuals grow up and their symptoms of ASD improve. Parents and caregivers focus on providing the best therapies possible for autistic children to develop to their highest potential. Because the incidence of ASD seems to be increasing at a rapid rate worldwide, enough so that the CDC has voiced concern about its prevalence, there is more awareness of ASD and more ongoing research efforts. People with ASD have a normal life expectancy and with proper intervention they can lead full lives.



Until the cause of ASD is discovered, prevention is not possible.



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Ellis, Michael A. Caring for ASD: Practical Advice from a Parent and Physician New York: Oxford University Press, 2018.

Honeybourne, Victoria. A Practical Guide to Happiness in Children and Teens on the ASD Spectrum: A Positive Psychology Approach. London: Jessica Kingsley, 2018.


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Shapin, Steven. “What Is ASD?” The New Yorker, January 25, 2015. (accessed April 17, 2018).

Szalavitz, Maia. “ASD: It's Different in Girls.” Scientific American, March 1, 2016. (accessed April 17, 2018).


Brasic, James R. “ASD.” Medscape. (accessed April 17, 2018).

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ASD Research Institute/ASD Resource Center, 4182 Adams Ave., San Diego, CA, 92116, (833) 281-7165, .

ASD Society of America, 4340 East-West Hwy., Ste. 350, Bethesda, MD, 20814, (800) 328-8476, .

ASD Speaks, 1 East 33rd St., 4th fl., New York, NY, 10016, (888) 288-4762, .

Carol A. Turkington
Revised by Tish Davidson, AM

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