Autism << AW tihz uhm >> is a disorder characterized by certain patterns in social communication and by the presence of restricted and repetitive behaviors. Autism-related behaviors are first seen in young children and persist throughout life. Some autism-related behaviors may be present in infancy. The condition may become more noticeable as autistic children reach the age when their peers are beginning to speak and participate in social play. Health experts refer to autism and related disorders collectively as autism spectrum disorder (ASD).
The United States Centers for Disease Control and Prevention estimates that autism and related disorders occur in about 1 of every 36 children in the United States. The World Health Organization (WHO) estimates that, worldwide, only 1 of every 100 children is diagnosed with autism. However, the WHO estimate includes children in middle-income and low-income countries, where it may be more difficult to see a doctor who can diagnose ASD. Boys are more commonly diagnosed with ASD than girls are.
Some people with the disorder prefer to be called autistic people. Others prefer to be described as people with autism. Both phrases will be used in this article.
The American psychiatrist Leo Kanner first described the symptoms in the 1940’s. He chose the name autism, from the Greek word for self, referring to the children’s apparent lack of interest in other people.
Characteristics of autism.
Doctors diagnose autism when a patient shows certain behaviors from each of three categories. The categories are (1) social interaction, (2) communication, and (3) restricted and repetitive interests and behaviors. These behaviors can occur in various combinations with different levels of severity.
Social interaction.
Autistic children may avoid certain social behaviors, such as seeking comfort from a parent, or making eye contact. They may not respond when their name is called. They may not play with other children. They may have difficulty making or keeping friends.
Communication.
Most children with autism do not develop language as early as others. Some never develop language. Autistic people often communicate with reduced facial expressions and gestures compared with nonautistic people. Autistic children with fluent speech may enjoy talking about a single subject. They may use words in a way that is unusually precise and literal. Some autistic people exhibit a speech pattern called echolalia, in which they repeat what is said to them before giving their own response, or instead of giving their own response.
Restricted and repetitive interests and behaviors.
Some children with autism may have intense interest in a specific topic, such as clocks, airplanes, Pokémon, or calendars. They may spend much of their time pursuing that interest, potentially to the exclusion of other activities. Children with autism may show repetitive body movements, such as hand flapping, rocking, or head banging. They may show repetitive behaviors in other ways, such as placing toys in a line.
Some autistic children may need sameness to feel comfortable—that is, they may become distressed by changes in their environment or routine. Some children with autism may be unusually sensitive to sound, light, or touch. They also may show preferences for certain sensations, such as how some things feel or look.
Other characteristics,
not part of the requirements for diagnosis, frequently occur with autism. They vary widely among individuals. Autistic people may move clumsily or have difficulty with tasks involving their hands, such as tying their shoes or writing. Some people with autism have better-than-average skills, such as unusually good memory or artistic ability. They may be able to focus on tedious tasks for long stretches of time. They may observe details most people would not notice.
Some people with autism have an intellectual disability. But autism occurs among individuals of all levels of intelligence. Children with autism tend to have brains that are somewhat larger than those of nonautistic children. Nonautistic children with an intellectual disability tend to have small brains. This difference suggests the causes of the two conditions are different, even though the conditions sometimes occur together.
Causes.
Scientists know that autism is caused by the way the brain develops. The differences in brain development between autistic and nonautistic people may begin before birth. However, the behaviors seen in autism are so complex that no single area of the brain can account for all of them. Even so, there is one consistent finding in the brains of people with autism. People with autism have a lower number of Purkinje << pur KIHN jee >> cells than other people do. These cells are important in the coordination of movement. They may also play a role in higher brain functions, such as planning and language. Scientists do not know, however, what role having fewer Purkinje cells plays in the symptoms of autism.
Scientists have also identified factors that indicate which infants are more likely to eventually receive an autism diagnosis. For example, infants with a small head size at birth who experience sudden, excessive growth in head size before 1 year of age are more likely to be diagnosed with autism.
Scientists know that susceptibility to autism is inherited. They have observed in families that parents, siblings, and other relatives of a child with autism often have some symptoms of the disorder. In addition, the diagnosis is more common in relatives than would be expected by chance. Children fathered by older men have a higher chance of developing autism than do those with younger fathers. About 1 percent of people with autism have duplicated or missing genes on one of the pair of chromosomes designated chromosome 16. Researchers think that autism likely results from the interaction of several genes that may be on different chromosomes.
Scientists also know that environmental factors play a role in autism and related disorders. Pregnant women who contract certain diseases, or have health conditions such as obesity or diabetes, have a greater likelihood of having a child with autism.
People sometimes falsely claim that vaccines can cause ASD. In 1998, a famous scientific paper claimed that 12 children had been diagnosed with autism after being vaccinated against measles, mumps, and rubella (MMR). Many people who heard this claim began to mistrust vaccines. Some parents refused to have their children vaccinated because they were afraid their children would develop autism. But scientists have determined that the MMR vaccine is not connected to autism. The researcher in charge of the famous paper misled readers about how he selected the data, and he had financial motives to make the MMR vaccine seem dangerous. The paper was retracted—that is, the publishers removed it from the record to prevent the spread of misleading information.
Intervention
can help with some behaviors of autism that may make daily life difficult. Behavioral interventions for autistic children, often classified as Naturalistic Developmental Behavioral Interventions (NDBI’s), are a kind of therapy that helps individuals adapt their behavior in everyday situations. For example, NDBI’s may help increase a person’s social engagement. Speech therapists help autistic people strengthen their communication skills. These skills can include learning to talk and to use pragmatic speech—that is, speech used in a social manner. Some people with autism work with physical therapists or occupational therapists. These therapists can help them learn to move less clumsily or to be less sensitive to sound, light, or textures. Drug therapy can help some patients stay calm or focus better on daily tasks.
People with autism benefit from accommodations (adjustments to regular procedures) that help them perform well at school and work. Accommodations can include changes in a schedule or in an environment. For example, an employee might be given a noise-canceling headset to block out distracting sounds. Students with autism might receive extra lessons to help them develop social skills. Accommodations work best when they are based on the specific needs of the individual.
