Researchers at the UC Davis have identified 10 locations in California where the incidence of autism is higher than in the surrounding areas in the same region. And the single factor that unites the clusters appears to be having parents with higher-than-average levels of education.
The study, published yesterday in the The Journal of Autism Research, used mapping software to pinpoint birth locations for 2.5 million children born in California from 1996 to 2000, roughly 10,000 of which were later diagnosed with an autism spectrum disorder.
Senior author Irva Hertz-Picciotto, PhD, explained in a release:
In the U.S., the children of older, white and highly educated parents are more likely to receive a diagnosis of autism or autism spectrum disorder. For this reason, the clusters we found are probably not a result of a common environmental exposure. Instead, the differences in education, age and ethnicity of parents comparing births in the cluster versus those outside the cluster were striking enough to explain the clusters of autism cases.
To put the study into a global perspective, The Mercury News reports:
A similar link between autism and education has been reported by researchers in several other nations. But in Denmark - which requires autism screening of all children - no difference was found among educational levels of parents.