self-fulfilling diagnosis of normotic illness? REDUX originally posted 1/12/10

ScientificAmerican | California scientists have discovered clusters of autism, largely in the Los Angeles and San Francisco areas, where children are twice as likely to have autism as children in surrounding areas.

The 10 clusters were found mostly among children with highly educated parents, leading researchers to report that they probably can be explained by better access to medical experts who diagnose the disorder.

Because of the strong link to education, the researchers from University of California at Davis said the new findings do not point to a localized source of pollution, such as an industry, near the clusters.

“I suspect access to services plays the major role,” said Irva Hertz-Picciotto, senior author of the study published Tuesday in the journal Autism Research.

She added, however, that there could be other reasons why higher-educated parents lead to more autism. Environmental exposures, such as chemicals from consumer products, could be more common in those households, she said.

“Certainly there may be some consumer products to which more educated persons are more likely to be exposed. There is undoubtedly a possibility of higher exposures in the more educated,” said Hertz-Picciotto, a professor of public health sciences and an autism expert at the UC Davis MIND Institute.

For the study, the researchers analyzed the birth records of about 2.5 million babies born in California between 1996 and 2000. Nearly 10,000 were later diagnosed with an autism spectrum disorder.

Autism is a neurological disorder involving impaired social development and communication skills. Experts believe that it is caused during pregnancy or early infancy since symptoms often arise by age two or three.

The new research is the first time that anyone has looked for geographic areas with high incidence, or clusters, of autism, according to lead author Karla Van Meter, an epidemiologist.

The 10 clusters were located in: the Torrance, Beverly Hills, Van Nuys and Calabasas areas of Los Angeles County; the Laguna Beach/Mission Viejo area of Orange County; the La Jolla/Del Mar area of San Diego County; San Francisco; the Sunnyvale/Santa Clara area; the Redwood City area; and Fresno. Two other possible clusters were also found in the Norwalk/Cerritos area of Los Angeles County and the Modesto area.