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The Chronicle of Higher Education

From the issue dated May 11, 2007
The Chronicle of Higher Education

Is There an Autism Epidemic?


According to some advocates, an epidemic of autism is attacking young children and the government has been woefully negligent in dealing with it. But many epidemiologists dismiss the evidence used to support the idea of an epidemic. The debate has grown so ugly that researchers say they are being threatened if they question evidence of an upsurge in autism.

At a recent meeting held by the National Academies' Institute of Medicine, Laura Bono, a board member of the National Autism Association, sounded the alarm. "This epidemic will cost society close to $2-trillion," she said. She also demanded that the government "declare autism a national health emergency."

Some groups of parents of children with autism argue that vaccines are to blame for the rising numbers of people diagnosed with the disorder. "There is a growing body of evidence implicating vaccine overload, mercury and aluminum from vaccines," said Ms. Bono at the meeting. "Thousands of parents agree with this research. They watched their children regress after being vaccinated."

Next month a court hearing will look at the vaccine question. Some 4,800 petitioners representing people with autism are suing the federal government, alleging that mercury-containing vaccines are to blame for their relatives' disorders.

One piece of evidence used to support the vaccine theory has been a rapid rise in the numbers of people diagnosed with autism. Special-education data for the United States, for example, show a 525-percent increase in the number of children classified in the autism category between 1994 and 2004.

But those numbers, taken on their own, can be deceiving, say epidemiologists. Paul T. Shattuck, a postdoctoral fellow at the University of Wisconsin at Madison, published a paper in Pediatrics last year that examined the increasing autism numbers. The year 1994 was unusual, he says, because it was the first year that all states used the new autism category in special education, a classification required by a 1990 federal law.

Anytime a new category is introduced, it takes time for that system to be adopted, he says. For example, the numbers of children classified with traumatic brain injury and developmental disability also increased in the years after they were included in states' special-education categories. Mr. Shattuck and his colleagues found that as autism rates rose, the prevalence of mental retardation and learning disabilities declined by roughly the same amount in the special-education data.

Such trends suggest that states were using the new autism category to classify children who would formerly have been included in the mental-retardation or learning-disabled groupings.

"We can't use special-ed trends to validly argue that there is or isn't an epidemic," says Mr. Shattuck.

Debating the Data

In his new book, Unstrange Minds: Remapping the World of Autism (Basic Books), Roy Richard Grinker, a professor of anthropology at George Washington University, argues that many factors have conspired to give the false impression of an epidemic. Psychiatrists have broadened the diagnosis of autism to include more people; society now recognizes the disorder more readily, so children are getting diagnosed more often and at younger ages; and there are more child psychiatrists who are familiar with and can diagnose the disorder.

"I use the analogy of a perfect storm," he says. "All of these factors coming together and acting together to give us a situation that feels in your gut like an epidemic."

Craig J. Newschaffer, a professor of public health at Drexel University, has studied the autism data, and he agrees that diagnostic changes and recognition are contributing to the rising rates, but he can't rule out the possibility of a true epidemic.

"I spent a lot of time looking at the evidence for both sides, and my feeling as an epidemiologist is that I don't have enough evidence on either side to say conclusively it's one way or the other." The data are simply not good enough to answer the question, he says.

Many advocates have pressed the question of an epidemic because it would offer some support for the idea that an environmental factor is causing more cases of autism than in the past. A study by the Institute of Medicine concluded in 2004 that there was no compelling evidence to link mercury-containing vaccines to the rising rates of autism, but researchers agreed at the conference last month that the government should focus more on examining a broad array of potential environmental factors that could contribute to autism, especially in people with a genetic predisposition.

In recent years, some researchers say they have received threats if their work questions the reality of an epidemic or a connection between vaccines and autism. An editorial this month in Nature Neuroscience says that people who oppose the mercury-autism hypothesis "have been harassed with repeated calls."

After Mr. Shattuck's paper last year, he received "a half-dozen phone messages on my answering machine that were either vaguely or specifically physically threatening," he said.

One person said, "Don't be surprised if you get a knock on your door in the middle of the night and I'll be there." Another message said it was easy in the age of the Internet to find out where people live.

"Nothing ever came of it, but it was nerve-racking," he says. "I have a family and a young child."
Section: Research & Publishing
Volume 53, Issue 36, Page A26

Copyright © 2007 by The Chronicle of Higher Education

©2007 Roy Richard Grinker