"Even though it seems like anybody and everybody has heard of autism, in many places in the world it's still sort of a new topic," says Charles Zaroff, assistant professor of psychology at the University of Macau in China.
The first prevalence studies in any region typically find low numbers. These low rates are likely to be the result of the methods used, experts say.
Data collected by the Centers for Disease Control and Prevention shows the highest autism prevalence in states with the best autism health and support services, such as Arizona (121 cases per 10,000 people), Missouri (121) and New Jersey (106). In contrast, areas with fewer services have lower rates, such as Alabama (60), Arkansas (69) and Florida (42).
Over time, however, as more parents and clinicians become familiar with autism, prevalence goes up. In many parts of the world, including the U.S., U.K., Canada, Japan and Scandinavia, "The rates were flat through the late '80s, and then suddenly a massive rise happened at same time," Fombonne says. The rise is probably not due to a mysterious global environmental exposure, he says. "It's more likely to reflect new concepts of autism worldwide."
(From "Researchers track down autism rates across the globe", Simons Foundation, April 2011)
