Autism spectrum disorders are disorders in which young children cannot develop normal social relationships, use language abnormally or not at all, and behave in compulsive and ritualistic ways.
Autism spectrum disorders (ASDs) are considered a spectrum of disorders because the manifestations vary widely in type and severity. Previously, ASDs were subclassified into classic autism, Asperger syndrome, Rett syndrome, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified. However, doctors currently do not use this terminology and consider these all as ASDs (except for Rett syndrome, which is a distinct genetic disorder). ASDs are different from intellectual disability (see Intellectual Disability), although many children with ASDs have both. The new classification system emphasizes that, within the broad spectrum, different features may occur more or less strongly in a given individual.
Symptoms of ASD may appear in the first 2 years of life, but in milder forms symptoms may not be detected until school age. These disorders occur in about 1 of 88 children based on recent population statistics and are 2 to 4 times more common among boys than among girls.
The specific causes of ASD are not fully understood, although they are clearly biologically determined. For parents of one child with an ASD, risk of having another child with an ASD is 50 to 100 times greater. Several genetic abnormalities, such as Fragile X syndrome and Down syndrome, may be associated with ASD. Prenatal infections, for example, viral infections such as rubella or cytomegalovirus, may also play a role. It is clear, however, that ASDs are not caused by poor parenting, adverse childhood conditions, or vaccination.
Children with ASD develop symptoms in the following areas:
Symptoms range from mild to severe, but all children require some level of support in both areas. Children often are unable to function independently in school or society, although the degree of support needed varies considerably. In addition, about 20 to 40% of children with ASD, particularly those with an IQ less than 50, develop seizures before reaching adolescence. In about 25% of affected children, a regression in development occurs around the time of diagnosis and may be the initial indicator of a disorder.
Social communications and interactions:
Often, infants with ASD do not cuddle and avoid eye contact. 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 are not able to interpret the moods and expressions of others. They have difficulty knowing how and when to join a conversation and recognizing inappropriate or hurtful speech. All these factors often cause others to view them as odd or eccentric and thus lead to social isolation.
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. Children may speak with an unusual rhythm and pitch.
Behavior, interests, and activities:
Children with ASD are very resistant to changes, such as new food, toys, furniture arrangement, and clothing. They often become excessively attached to particular inanimate objects. Repetition is typical. Younger and/or more severely affected children often repeat certain acts, such as rocking, hand flapping, or spinning objects. Some may injure themselves through repetitive behaviors such as head banging or biting themselves. Less severely affected children may watch the same video multiple times or insist on eating the same food every meal. Children typically have very specialized, often unusual interests. For instance, a child may be preoccupied with vacuum cleaners.
Children often have over-reactions or under-reactions 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.
Many children 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 children with ASD have idiosyncratic or splinter skills, such as the ability to carry out complex mental arithmetic or advanced musical skills. Unfortunately, such children often cannot use these skills in a productive or socially interactive way.
The diagnosis is made by close observation of the child in a playroom setting and careful questioning of parents and teachers. Standardized screening tests, such as the Social Communication Questionnaire and the Modified Checklist for Autism in Toddlers (M-CHAT) may help identify children who need more in-depth testing. Psychologists and other specialists may use the more extensive Autism Diagnostic Observation Schedules and other tools. In addition to giving standardized tests, doctors should do certain tests to look for underlying treatable or inherited medical disorders, such as hereditary metabolic disorders (see Overview of Hereditary Metabolic Disorders) and Fragile X syndrome (see Fragile X Syndrome).
Prognosis and Treatment
The symptoms of ASD generally persist throughout life. The prognosis is strongly influenced by how much usable language the child has acquired by age 7. Children with ASD who have lower measured intelligence—for example, those who score below 50 on standard IQ tests—are likely to need more intensive support as adults.
Children with ASD often benefit from intensive behavioral modification techniques. Children with higher IQs are helped by therapy aimed at developing social skills. Individualized special education is crucial and often includes speech, occupational, physical, and behavioral therapy within a program equipped to manage children with ASD.
Drug therapy cannot change the underlying disorder. However, the selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, paroxetine, and fluvoxamine, are often effective in reducing ritualistic behaviors of children with ASD. Antipsychotic drugs, 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 children 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 helps 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 physician regarding benefits and risks.
Rett syndrome is a rare genetic disorder occurring almost only in girls that causes impaired social interactions, loss of language skills, and repetitive hand movements. Although many symptoms resemble those of an autism spectrum disorder, Rett syndrome is distinct.
Girls with Rett syndrome appear to develop normally until some time between the age of 5 months and 4 years. When the disorder begins, head growth slows and language and social skills deteriorate. Typically, girls display repetitive hand motions resembling washing or wringing. Purposeful hand movements are lost, walking is impaired, and trunk movements are clumsy. Intellectual disability develops and is usually severe. Seizures often occur, and over time mobility may be affected.
Slight spontaneous improvements in social interaction may occur in late childhood and early adolescence, but the language and behavior problems progress. Most girls with Rett syndrome need full-time support and specialized educational programs. There is no cure yet identified. Drugs may help with some symptoms, particularly seizures.
Last full review/revision November 2013 by Stephen Brian Sulkes, MD