Autism Jump In California Puzzles Researchers

SACRAMENTO, Calif. -- Researchers want to know why there has been a 273 percent increase in autism cases in 12 years among California children, when normal population growth should only bring a 20 percent increase.

Researchers at the University of California at Davis said the huge jump occurred between 1987 and 1998.

Researchers found that better detection methods had little to do with the problem, and they ruled out statistical errors. Even loosening the criteria for diagnosing autism didn't explain away the big numbers.

Also, more than 90 percent of the children in the survey were native-born Californians, so major migration of children into California did not contribute to the increase, the researchers said.

"Speculation about the increase in autism in California has led some to try to explain it away as a statistical issue or with other factors that artificially inflated the numbers," said pediatric epidemiologist Robert Byrd, lead researcher of the study. "Instead, we found that autism is on the rise in the state and we still do not know why. The results of this study are, without a doubt, sobering."

Autism affects a person's ability to communicate, form relationships and respond to the environment.

Byrd said it's time to rethink the possible causes of autism. Researchers also want to look into vaccines, which some believe trigger autism, and whether parents can be genetic carriers. That will take more study and more funding.

Find more autism details at the University of California-Davis Mind Institute site.