Children with autism, also called autistic disorder, have problems interacting and communicating with others. Autism appears before the third birthday, causing children to act inappropriately, often repeating behaviors over long periods of time. For example, some children bang their heads, rock, or spin objects. Symptoms of autism range from mild to severe. Children with autism may have a very limited awareness of others and are at increased risk for other mental disorders. Studies suggest that autism affects 10 to 12 of every 10,000 children (U.S. Department of Health and Human Services, 1999).