In the United States, autism may affect up to 115,000 children between one and 15 years of age, but its prevalence in adults is uncertain. Classic autism is one of a group of development disorders in which a wide variety of behaviors and activities are demonstrated that collectively are known as pervasive development disorder (see the accompanying table on criteria for autistic disorder). Certain biologic conditions and/or genetic factors appear to be associated with the development of autism, but no specific cause has been identified. Multiple members of a family may be affected, but currently no common genetic defect is observable in affected children. Rapin reviewed the many manifestations of autism, principal symptoms, therapies and prognosis.

Autism can first appear as impaired attachment in infants, but this behavior generally occurs in toddlers, typically in boys from 18 to 30 months of age. They may demonstrate affection but without any joy or reciprocity. In these children, parents also report delayed speech, lack of normal interest in others or in childhood activities, or a regression of early speech and sociability.

Communication difficulties are the most serious problem. Patients with verbal auditory agnosia (“word deafness”) understand little or no language (see accompanying table on communication deficits in autism). In addition, children with autism do not play normally. While they may appear to have long attention spans when engaged in solitary activities, they cannot focus on activities performed jointly with others. Parents may describe them as independent rather than aloof and may even be proud of their self-sufficiency. Children with autism have frequent temper tantrums, require less sleep and awaken frequently during the night. Approximately 75 percent of children with autism are mentally retarded, but a small minority excel at music, mathematics or visual spatial tasks.

Neurologic problems associated with autism include joint laxity, hypotonia, clumsiness, apraxia, toe walking, motor stereotypies (such as hand flapping, pacing, spinning, running in circles) and oral stereotypies (such as humming). Self-destructive behavior such as biting and head banging may be the result of increased endorphin levels. These children may be either hypersensitive or oblivious to sounds, tactile stimuli, pain and tastes. As adolescents, they frequently demonstrate detachment, depression and unprovoked aggression.

The functional status of persons with autism varies widely. They may not function well enough to perform activities of daily living or, alternatively, they may successfully complete college and function independently. In well-functioning adults, stereotypies, such as finger rubbing, may persist unnoticed. However, by the time a child with autism reaches adulthood, he or she has likely had at least two seizures. In addition, autism in adults may be confused with other diagnoses such as obsessive-compulsive disorder, schizoid personality, simple schizophrenia, affective disorder, mental retardation or brain damage.

Mainstream treatment consists of early, intensive education for parents, focusing on behavior and communication disorders. A highly structured environment with intensive individual instruction should be encouraged. Laboratory, metabolic or genetic tests and diagnostic imaging provide little useful information, although an electroencephalogram (EEG) is indicated in children in whom epilepsy is suspected. No specific pharmacologic therapies are available, but many patients do not require medication. When needed, medication is generally used for a particular manifestation or constellation of symptoms. Families may benefit from ongoing counseling and support, and specific instructions for dealing with tantrums and destructive behavior. Parents should be cautioned about costly and often questionable dietary, medical and other unconventional therapies.