Autism spectrum disorder is a condition in which people have difficulty developing normal social relationships, use language abnormally or not at all, and show restricted or repetitive behaviors.
Affected people have difficulty communicating with and relating to others.
People with autism spectrum disorder also have restricted patterns of behavior, interests, and/or activities and often follow rigid routines.
Diagnosis is based on observation, reports of parents and other caregivers, and standardized autism-specific screening tests.
Most people respond best to highly structured behavioral interventions.
Autism spectrum disorder (ASD) is a neurodevelopmental disorder. Neurodevelopmental disorders are neurologically based conditions that can interfere with the acquisition, retention, or application of specific skills or sets of information. They may involve dysfunction in attention, memory, perception, language, problem-solving, or social interaction.
Previously, autism spectrum disorder was subclassified into classic autism, Asperger syndrome, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified. However, there was so much overlap that it was hard to make distinctions, so doctors no longer use this terminology and consider these all as ASD (except for Rett syndrome, which is a distinct genetic disorder). ASD is different from Rett syndrome, although many people with ASD have both. The classification system emphasizes that, within the broad spectrum, different features may occur more or less strongly in a given individual.
ASD occurs in about 1 of 31 people in the United States and approximately 1/100 worldwide. ASD is 4 times more common among boys than among girls. The estimated number of people identified with autism spectrum disorder has risen because doctors and caregivers have learned more about the symptoms of the disorder.
Causes of Autism Spectrum Disorder
The specific causes of autism spectrum disorder are not fully understood, although there is strong evidence that the disorder has a genetic basis. It is highly heritable, or passed down in the genes, and parents of 1 child with ASD have a 20% risk of having another child with ASD. If one of a pair of identical twins (those that come from the same fertilized egg) has ASD, the other is more likely to have it, too. Several genetic abnormalities, such as fragile X syndrome, tuberous sclerosis complex, and Down syndrome, may be associated with ASD.
Prenatal infections, for example, viral infections such as rubella or cytomegalovirus, may play a role. Preterm birth (prematurity) may also be a risk factor: the greater the level of prematurity, the greater the risk of ASD.
Some children who have ASD have differences in how their brain is formed and how it functions.
It is clear, however, that ASD is not caused by poor parenting or adverse childhood conditions. There is compelling evidence that vaccinations do not cause autism (see also MMR vaccine and concerns about autism).
Symptoms of Autism Spectrum Disorder
Symptoms of autism spectrum disorder may appear in the first 2 years of life, but in milder forms symptoms may not be detected until school age.
Children with autism spectrum disorder develop symptoms in the following areas:
Social communications and interactions
Restricted, repetitive patterns of behavior
Symptoms of ASD range from mild to severe, but most people require some level of support in both areas. People with ASD vary widely in their ability to function independently in school or society and in their need for supports. In about 25% of affected children, a loss of previously acquired skills (regression in development) occurs around the time of diagnosis and may be the initial indicator of a disorder. In addition, many children with ASD develop seizures before reaching adolescence, especially if they also have intellectual disability.
Social communications and interactions
Often, infants with ASD cuddle and make eye contact in atypical ways. Although some affected infants become upset when separated from their parents, they may not turn to parents for security as do other children. Older children often prefer to play by themselves and do not form close personal relationships, particularly outside of the family. When interacting with other children, they may not use eye contact and facial expressions to establish social contact, and they have difficulty interpreting the moods and expressions of others. They may have difficulty knowing how and when to join a conversation and difficulty recognizing inappropriate or hurtful speech. These factors may cause others to view them as odd or eccentric and thus lead to social isolation.
Language
The most severely affected children never learn to speak. Those who learn may do so much later than normal and use words in an unusual way. They often repeat words spoken to them (echolalia), use memorized scripted speech in place of more spontaneous language, or reverse the normal use of pronouns, particularly using you instead of I or me when referring to themselves. Conversation may not be interactive, and, when present, is used more to label or request than to share ideas or feelings. People with ASD may speak with an unusual rhythm and pitch.
Behavior, interests, and activities
People with ASD are often very resistant to changes, such as new food, toys, furniture arrangement, and clothing. They may become excessively attached to particular inanimate objects. They often do things repetitively. Younger and/or more severely affected children often repeat certain acts, such as rocking, hand flapping, or spinning objects (self-stimulatory behavior, or "stimming"). Some may injure themselves through repetitive behaviors such as head banging or biting themselves. Less severely affected people may watch the same video multiple times or insist on eating the same food every meal. People with ASD often have very specialized, often unusual interests. For instance, a child may be preoccupied with vacuum cleaners.
People with ASD often have overreactions or underreactions to sensations. They may be extremely repelled by certain odors, tastes, or textures, or react unusually to painful, hot, or cold sensations that other people find distressing. They may ignore some sounds and be extremely bothered by others.
Intelligence
Many people with ASD have some degree of intellectual disability (an IQ less than 70). Their performance is uneven. They usually do better on tests of motor and spatial skills than on verbal tests. Some people with ASD have idiosyncratic or "splinter" skills, such as the ability to carry out complex mental arithmetic or advanced musical skills. Unfortunately, such people often cannot use these skills in a productive or socially interactive way.
Diagnosis of Autism Spectrum Disorder
A doctor's evaluation
Reports of parents and other caregivers
Standardized autism-specific screening tests
The diagnosis of autism spectrum disorder is made by close observation of the child in a playroom setting and careful questioning of parents and teachers. Standardized autism-specific screening tests, such as the Social Communication Questionnaire for older children and the Modified Checklist for Autism in Toddlers, Revised, with Follow-Up (M-CHAT-R/F), may help identify children who need more in-depth testing. Screening tests usually begin around 18 to 24 months of age. Psychologists and other specialists may use the more extensive Autism Diagnostic Observation Schedules and other tools.
Autism is sometimes classified into levels based on how much support a person needs to navigate their daily life:
Level 1: Requires some support (coaching in social and behavioral skills)
Level 2: Requires substantial support (structured environment and activity, some assistance with daily living)
Level 3: Requires very substantial support (intensive support throughout the day)
In addition to giving standardized tests, doctors do certain blood or genetic tests to look for underlying treatable or inherited medical disorders, such as hereditary metabolic disorders and fragile X syndrome or Rett sydrome in girls.
Treatment of Autism Spectrum Disorder
Applied behavior analysis
Educational programs
Speech and language therapy
Sometimes medication therapy
Treatment of autism spectrum disorder is best done using a multidisciplinary approach, focusing on managing specific behaviors to encourage meaningful social interaction and communication.
Applied behavior analysis (ABA) is an approach to therapy in which children are taught specific cognitive, social, or behavioral skills in a stepwise fashion. Small improvements are reinforced and progressively built upon to improve, change, or develop specific behaviors in children who have ASD. These behaviors include social skills, language and communication skills, reading, and academics as well as learned skills such as self-care (for example, showering and grooming), daily-living skills, punctuality, and job competence. This therapy is also used to help children minimize behaviors (for example, aggression) that may interfere with their progress. ABA is tailored to meet the needs of each child and is typically designed and supervised by professionals certified in behavior analysis (such as a board-certified behavior analyst [BCBA]). In the United States, ABA may be available as part of an Individualized Educational Plan (IEP) through schools. Another intensive behaviorally based intervention is the Developmental, Individual-differences, and Relationship-based (DIR®) model, also called Floortime. DIR® draws on the child's interests and preferred activities to help build social interaction skills and other skills. At present, there is less evidence to support DIR/Floortime® than ABA, but both therapies can be effective.
Educational programs for school-aged children with ASD should address social skills development and speech and language delays and help prepare children for education after high school or for employment.
The federal Individuals with Disabilities Education Act (IDEA) requires public schools to provide free and appropriate education to children and adolescents with ASD. Education must be provided in the least restrictive, most inclusive setting possible—that is, a setting where the children have every opportunity to interact with nondisabled peers and have equal access to community resources. The Americans with Disability Act and Section 504 of the Rehabilitation Act also provide for accommodations in schools and other public settings.
Medication therapy cannot change the underlying disorder, but it can help with symptoms. Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, paroxetine, and fluvoxamine, are often used to try to reduce anxiety and ritualistic behaviors of people with ASD. Antipsychotic medications, such as risperidone, may be used to reduce self-injurious behavior, although the risk of side effects (such as weight gain and movement disorders) must be considered. Mood stabilizers and psychostimulants may be helpful for people who are inattentive or impulsive or who have hyperactivity.
Although some parents try special diets, gastrointestinal therapies, or immunologic therapies, currently there is no good evidence that any of these therapies are helpful in children with ASD. Other complementary therapies, such as facilitated communication, chelation therapy, auditory integration training, and hyperbaric oxygen therapy, have not been proved effective. In considering such treatments, families should consult with the child's primary care physician regarding benefits and risks.
Prognosis for Autism Spectrum Disorder
In most people, symptoms of ASD persist throughout life. At present, most adults with ASD live with family or in group living situations, while about a quarter live on their own or in their own households; this is improving over time with increasing intervention available to younger children. The prognosis is strongly influenced by how much usable language the child has acquired by elementary school age.
More Information
The following English-language resources may be useful. Please note that The Manual is not responsible for the content of these resources.
These following organizations provide support, community, and educational resources for people with and caregivers of people with autism spectrum disorder:
Drug Information for the Topic
