A mental disorder that is characterized by repetitive behavior and a seriously impaired ability to communicate and interact with others.

Childhood autism (sometimes called pervasive developmental disorder) is characterized by a profound difficulty in social relationships. A disorder that appears in early childhood—generally by age three—autism is not completely understood by researchers but is likely to be due to abnormal brain development. The disorder differs from child to child, but autism may be first suspected when an infant or toddler fails to develop normal social interactions, such as eye contact with parents. When in the company of others, autistic children may display repetitive movements such as rocking, head banging, or hand twisting. These children also exhibit markedly delayed language or unusual language use, avoidance of eye contact, an obsessional concern for order and sameness, and an aversion to or lack of interest in other persons.

Autism...