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New Intensity to Debate Over Autism Cause

Parents and Researchers Grapple With Claims That Autism Is Linked to Thimerosal in Vaccines


Eric Fombonne, MD, FRCPsych, of the Institute of Psychiatry at King's College, London, has studied autism in the U.K.

"From our data, we can say that we have a prevalence that is 62 cases per 10,000 children," he told WebMD in a 2001 interview. "In the mid-1960s, we showed rates of 4 cases per 10,000."

Isn't this the sign of an epidemic? Not necessarily.

"You cannot compare studies now to studies from 30 years ago," Fombonne said. "It would be comparing oranges not with apples, but with sheep."

Children with autism vary widely. It was not until 1940 that this constellation of problems with social interaction, communication, and focused interest came to be called autism. And it was not until 1980 that the diagnosis of autism was formalized.

In 1994, the diagnosis changed again. Kids diagnosed with autism from 1980 through 1993 had to meet six mandatory criteria. The new 1994 definition offered 16 optional criteria, only eight of which had to be met. Gernsbacher says the 1994 diagnosis made it much easier for a child to be labeled autistic.

The federal Individuals with Disabilities Education Act, passed in 1991, assures appropriate public education for children with autism. Soon after, schools began reporting high numbers of students with autism. Those numbers keep going up. But that doesn't mean there's an autism epidemic, Gernsbacher says, any more than increased sales of petite clothing means women are getting smaller.

"My hunch is that if we looked at the production and purchase of petite-sized clothing we'd see a greatly increasing trend in the number of petite-sized garments produced and purchased over the past two decades," she says. "Should we therefore conclude that U.S. women are getting increasingly more petite? Probably not. There was probably always a contingent of petite-sized women, and their needs are being increasingly better met."

Gernsbacher points to data from Fombonne and others suggesting that there are 5.8 to 6.7 autism cases among every 1,000 U.S. children. If that's so, we haven't found them all yet. Even Oregon, which led the nation with 4.3 autism cases per 1,000 children in 2002-2003, still has a way to go. Other states lag much farther behind.

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