Questions Still Surround Autism

Aug. 1 -- Sean Green was a happy, easygoing baby until one morning, when everything changed.

"He didn't know who I was," his mother, Cyndi Greene, told ABCNEWS correspondent Jackie Judd on World News Tonight. "He looked right through me."

The diagnosis was autism. The brain disorder left Sean lethargic, unresponsive to sounds, disconnected from the world around him.

Dr. Jeff Bradstreet says he sees more and more children like Sean. In fact, he has a waiting list just to get on the waiting list.

"We all feel like we're the captain of a lifeboat of the Titanic trying to decide who can we let in when we're surrounded by people who are more or less drowning with the disease," says Bradstreet.

Rising Numbers

A decade ago in Loudon County, Va., four autistic children attended public schools. Today, there are 181.

And it costs twice as much money to educate them as other children

"With the rising numbers, the growing needs, the individual needs of students, because students with autism vary so greatly, I think it's going to be quite a challenge," says Charlotte Crane, an autism resource specialist in the county.

The great mystery is why the number of children with this disorder, which affects how different parts of the brain communicate, is rising.

"It presumably affects the developing brain prior to birth," says Wendy Stone, clinical psychologist at Vanderbilt University Medical Center in Nashville, Tenn. "It is generally assumed that there is no single cause of autism in all cases, but that a variety of different causes, alone and in combination, contribute to the development of autism in different individuals."

Nancy Minshew, director of the Collaborative Program of Excellence in Autism at the University of Pittsburgh, says the environment may play a part.

"It's a polygenetic disorder, which means each case is caused by three to four interacting genes, but you can't have a genetic epidemic. So the increase would have to be a genetic-environmental interaction. I don't think anybody had a clue, which is scary," she says.