How has autism prevalence changed over time?
The latest estimate of autism prevalence—1 in 68—is up 30 percent from the 1 in 88 rate reported in 2008, and more than double the 1 in 150 rate in 2000. In fact, the trend has been steeply upward since the early 1990s, not only in the U.S. but globally, says Maureen Durkin, who heads the network site in Wisconsin.
How accurate is the CDC’s approach?
The strength of the approach is that it takes a snapshot of all children who live in a certain area, not just those who have a diagnosis, according to Eric Fombonne, professor of psychiatry at Oregon Health and Science University in Portland. But, he notes, relying on school and medical records is not as accurate as assessing a child in person.
The approach also misses children who have no school or medical records, including some who are home-schooled or live in isolated regions. And children within the monitored areas may not be representative of all children in a state.
One indication that the method is imperfect is the fact that autism rates vary dramatically between states. The prevalence in Colorado, for instance, is 1 in 93 children, whereas in New Jersey it is 1 in 41. It is unlikely that the rates naturally vary that much between states, Fombonne says. Instead, the difference probably reflects varying levels of autism awareness and of services offered in those states.