Madison, Wis.

TODAY the special “vaccine court” at the United States Court of Federal Claims in Washington will begin hearing Cedillo v. Secretary of Health and Human Services, the first case of about 4,800 similar ones to examine whether childhood vaccinations can cause autism. We have no wish to comment on these legal issues. But having spent years researching the prevalence of autism in American children, we are concerned that publicity surrounding the case will only drag out debate about whether past trends indicate we face an autism “epidemic.”

The claims for or against an autism epidemic simply cannot be proved given the evidence available. (Public attention to the issue was set off primarily by a 1999 report by the State of California that found “a 273 percent increase in the number of persons with autism between 1987 and 1998.”) In the end, arguing over what the old data mean just detracts from the more pressing issues involved with scientific research and building cost-effective support systems for affected children, adults and their families.

The latest data from the Centers for Disease Control and Prevention indicate that 1 in 150 8-year-old children are on the “autism spectrum.” This proportion is alarming if compared directly to estimates of the frequency of autism before the 1990s, which were in the range of 1 per 2,000 to 5,000. But does this really mean we have a growing autism epidemic, or have we just become better at counting autistic traits in the population that have always been there at roughly the same level?

What remains undisputable is that more and more children are being labeled with autism. In 1943, when the child psychiatrist Leo Kanner published the first case studies of autism as a medical condition, it was characterized by very severe impairments in social interaction and language and communicative abilities, combined with the presence of unusual repetitious behaviors.