Autism is a complex, lifelong biological disorder of development that results in social interaction problems, communication difficulties and restrictive or repetitive interests and behaviors. The estimated prevalence of autism is from approximately one in 500 children to one in 1,000 children who might be affected by some form of the disorder.

Autism can be reliably diagnosed by or before age 3. Parents and expert clinicians can usually detect symptoms during infancy, although a formal diagnosis is generally not made until the child fails to develop functional language by age 2. Approximately 20 percent of children with autism reportedly experience a "regression" – that is, they have apparently normal development followed by a loss of communication and social skills.

Boys are three to four times more likely to be affected by autism than girls. Autism occurs in all racial, ethnic and social groups.

Although there is currently no known cure for autism, it is treatable. Persons with autism can make progress if they receive appropriate, individual intervention. Preschool children who receive intensive, individualized, behavioral interventions show remarkable progress.

In the majority of cases, no specific underlying cause can be identified. However, a variety of factors are being investigated. These include infectious, metabolic, genetic and environmental factors. However, in 1995 a working group convened by the National Institutes of Health in 1995 reached a consensus that autism probably results from a genetic susceptibility that involves multiple genes.

Information courtesy of The National Institute of Child Health and Human Development.