Autism is one of a group of serious developmental problems called autism spectrum disorders (ASD) that appear in early childhood — usually before age 3. Though symptoms and severity vary, all autism disorders affect a child's ability to communicate and interact with others.

It's estimated that three to six out of every 1,000 children in the United States have autism — and the number of diagnosed cases is rising. It's not clear whether this is due to better detection and reporting of autism, a real increase in the number of cases, or both.

What is clear is that though there is no cure for autism, intensive, early treatment can make an enormous difference in the lives of many children with the disorder.