Number of autism cases on the rise — but why?

It's one of the worst nightmares a parent can imagine — without warning, a child is abducted from his bed in the middle of the night, never to return.

Now, imagine that instead of taking the whole child, only his mind is stolen and his body — the hollow shell of his being — is left behind.

That's the way parents of children with autism feel, said Hollywood producer Jon Shestack, whose 11-year-old son is autistic.

"If one in every 250 children in America were actually being abducted, that would be a national emergency," Shestack said. "But that is what is happening with autism and it is a national emergency."

Autism — a devastating brain disorder that usually appears before age 3 and affects a child's ability to communicate, form relationships and respond to the world around him — used to be rare but is now at least as prevalent as childhood cancer or diabetes. Though the disorder takes many forms, in most cases children seem to withdraw into their own worlds.

Autism skyrocketing

In the 1970s, autism was estimated to have affected about 1 in 2,500 to 5,000 children. Studies show it occurs today in 1 in 150 to 500 children. About 1.5 million Americans are autistic. Boys are affected three to four times as often as girls.

Although the phenomenon has been reported across the country and in much of the industrialized world, some scientists believe the increase is due to an expansion of diagnostic criteria and better identification of children with autism. However, a study commissioned by the California General Assembly concluded that the increase cannot be explained away by better data or past misclassification.

Some scientists, public health advocates and parents are calling it an epidemic. The question they are asking is whether some facet of modern society — toxic chemicals, vaccines, changes in lifestyle or diet — is stealing children's minds?

Relatively little is known about the cause of autism, first identified in 1943. Money for research was almost nonexistent until parents began lobbying Congress and raising funds themselves after autism rates began climbing in the 1990s.

"In 1993, there were probably 12 scientists in the whole country who were lonely and devoted and in a desert working on autism," said Shestack, who helped create the research foundation, Cure Autism Now, with his wife, Portia Iversen.