After rising inexplicably for years, the rate of schoolchildren with autism may be stabilizing, new research suggests.

In a study looking at special education classifications for elementary school students in Wisconsin from 2002 to 2008, researchers writing in the November issue of the journal Pediatrics report that autism occurrences look to be stabilizing across school districts in the state at a rate of about 1 percent.

The latest estimate from the Centers for Disease Control and Prevention shows autism occurring at a similar rate of one out of 110 children nationally.

Interestingly, while the number of children with autism grew in Wisconsin schools where few had the disorder to start, the rate remained largely unchanged in schools with higher prevalence at the beginning of the study. The result: by 2008, the rate of students with autism statewide became more equal across school districts.

“The disparity in prevalence between districts decreased considerably during the study period,” researchers from the University of Wisconsin wrote in Pediatrics. “If we assume that these trends will continue, then we would expect the overall (statewide) proportion of children served under the autism category to continue to increase in the near future and perhaps to level off in the range of the highest prevalence districts today.”

Autism is one of 11 disability categories available to Wisconsin school districts to classify special education students. Children do not need a medical diagnosis of autism to be placed in the category by their school.

The findings could have implications beyond Wisconsin, according to Dr. John Harrington, who was not involved in the study but who wrote a commentary about the findings that also appears in Pediatrics.

“If our population-based prevalence rates for ASD are matching our school-based rates then we can start making educated decisions for planning how to teach and transition this large group of students to adulthood and beyond,” Harrington writes.

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