Some Facts about Autism

A syndrome beginning in infancy and characterised by a lack of responsiveness to other people, gross impairment in verbal and nonverbal communication skills, and bizarre responses to the environment.

Autism is not a disease, but a developmental disorder of brain function. People with classical autism show three types of symptoms: impaired social interaction, problems with verbal and nonverbal communication and imagination, and unusual or severely limited activities and interests. Symptoms of autism usually appear during the first three years of childhood and continue throughout life. Although there is no cure, appropriate management may foster relatively normal development and reduce undesirable behaviors. People with autism have a normal life expectancy.

Autism affects an estimated 10 to 20 of every 10,000 people, depending on the diagnostic criteria used. Most estimates that include people with similar disorders are two to three times greater. Autism strikes males about four times as often as females, and has been found throughout the world in people of all racial and social backgrounds.

Autism varies a great deal in severity. The most severe cases are marked by extremely repetitive, unusual, self-injurious, and aggressive behavior. This behavior may persist over time and prove very difficult to change, posing a tremendous challenge to those who must live with, treat, and teach these individuals. The mildest forms of autism resemble a personality disorder associated with a perceived learning disability.

The hallmark feature of autism is impaired social interaction. Children with autism may fail to respond to their names and often avoid looking at other people. Such children often have difficulty interpreting tone of voice or facial expressions and do not respond to others' emotions or watch other people's faces for cues about appropriate behavior. They appear unaware of others' feelings toward them and of the negative impact of their behavior on other people.

Many children with autism engage in repetitive movements such as rocking and hair twirling, or in self-injurious behavior such as biting or head-banging. They also tend to start speaking later than other children and may refer to themselves by name instead of "I" or "me." Some speak in a sing-song voice about a narrow range of favorite topics, with little regard for the interests of the person to whom they are speaking.

People with autism often have abnormal responses to sounds, touch, or other sensory stimulation. Many show reduced sensitivity to pain. They also may be extraordinarily sensitive to other sensations. These unusual sensitivities may contribute to behavioral symptoms such as resistance to being cuddled.

Autism is classified as one of the pervasive developmental disorders. Some doctors also use terms such as "emotionally disturbed" to describe people with autism. Because it varies widely in its severity and symptoms, autism may go unrecognized, especially in mildly affected individuals or in those with multiple handicaps.

Researchers and therapists have developed several sets of diagnostic criteria for autism. Some frequently used criteria include:



  • Absence or impairment of imaginative and social play.
  • Impaired ability to make friends with peers.
  • Impaired ability to initiate or sustain a conversation with others.
  • Stereotyped, repetitive, or unusual use of language.
  • Restricted patterns of interests that are abnormal in intensity or focus.
  • Apparently inflexible adherence to specific routines or rituals.
  • Preoccupation with parts of objects.

Since hearing problems can be confused with autism, children with delayed speech development should always have their hearing checked. Children sometimes have impaired hearing in addition to autism. About half of people with autism score below 50 on IQ tests, 20 percent score between 50 and 70, and 30 percent score higher than 70. However, estimating IQ in young children with autism is often difficult because problems with language and behavior can interfere with testing. A small percentage of people with autism are savants. These people have limited but extraordinary skills in areas like music, mathematics, drawing, or visualization.

Autism has no single cause. Researchers believe several genes, as well as environmental factors such as viruses or chemicals, contribute to the disorder. Studies of people with autism have found abnormalities in several regions of the brain, including the cerebellum, amygdala, hippocampus, septum, and mamillary bodies. Neurons in these regions appear smaller than normal and have stunted nerve fibers, which may interfere with nerve signaling. These abnormalities suggest that autism results from disruption of normal brain development early in fetal development. While these findings are intriguing, they are preliminary and require further study. The early belief that parental practices are responsible for autism has now been disproved.

Some doctors speculate that autism may be the result of a specific brain injury or brain abnormality that occurred during brain development (before birth) or early in infancy. Others have found evidence that the disorder is a result of abnormal levels of neurotransmitters (chemicals that transmit messages between cells in the brain and nerves), especially the neurotransmitters dopamine and serotonin.

Recent studies strongly suggest that some people have a genetic predisposition to autism. Scientists estimate that, in families with one autistic child, the risk of having a second child with the disorder is approximately five percent, or one in 20, which is greater than the risk for the general population.

There is no cure for autism at present. Therapies, or interventions, are designed to remedy specific symptoms in each individual. The best-studied therapies include educational/behavioral and medical interventions. Although these interventions do not cure autism, they often bring about substantial improvement.

  • Facts About Autism. NIH Publication No. 96-1877. National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-2540