To say there’s a big debate over autism is an understatement. More than 5,000 families have filed court claims blaming vaccine makers for their children’s autism symptoms—including serious language delays, poor social skills, and repetitive movements—yet the research to date repeatedly shows no connection between vaccines and autism. A recent court decision added fuel to the fire by awarding compensation to the family of a young girl who developed autism symptoms after being vaccinated. What’s the real story? Health asked leading autism researchers to help us figure it out.

Q: Why does there seem to be a sudden epidemic of autism?
A: Epidemic may be the wrong word. In the mid-1970s the reported rate of autism was 21 in 10,000 children, or 1 in 470. Today it’s 65 to 67 per 10,000, or 1 in 150—about a threefold increase in 30 years. While any uptick in these numbers is worrisome, scientists aren’t calling that an epidemic. Many experts believe the actual rise in autism cases (additions to the amount typically seen in the general population) is quite small. The surge in diagnoses, they say, is largely due to a broader understanding of what qualifies as autism, greater awareness of the disorder, and the increased availability of services for children with autism symptoms.

To better understand that argument, consider this: Many children who are classified as autistic today would have been diagnosed with speech disorders or mental retardation 30 years ago. Indeed, as the number of children with autism has climbed, the number diagnosed with mental retardation has dropped. “These factors could explain all of the increase in autism cases,” says autism expert Eric Fombonne, MD, head of the department of psychiatry at Montreal Children’s Hospital.

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