Higher Rates of Autism Found in Clusters Around Los Angeles


Researchers at the U.C. Davis MIND Institute have discovered regions in the state of California that have notably higher autism incidence. But the story is more complicated, and more sad, than one might think at first. Instead of indications of an “autism epidemic”, these clusters point to the fact that minority and poor children are much less likely to receive autism diagnoses.

I don’t have the paper yet (I’m still trying to find the abstract), but articles in the Woodland Daily Democrat and the San Diego Union-Tribune are reporting the story.

The clusters do not appear to point to environmental causes. Instead…well, read for yourself:

Researchers said that in this investigation the clusters probably are not correlated with specific environmental pollutants or other “exposures.” Rather, they correlate to areas where residents are more educated.

Children with autism diagnoses in these clusters are more likely to be White and have parents with high education levels. Again, a quote:

“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,” said senior author Irva Hertz-Picciotto.

Kids in the “clusters” are about twice a likely to be diagnosed autistic and kids in nearby areas.

Twice as high. To the many of us armchair epidemiologists who who have looked closely at the California Department of Developmental Services (CDDS) data, this comes as no surprise.

For me, the most memorable discussion of the autism clusters came from Autism Diva, in her post from July 1997, Malibu and Compton: Compare and Contrast.

Here is a graph from that post:

The South Central Regional Center, in a predominantly non-White, poor area of the Los Angeles basin, had an administrative prevalence of 33 per 10,000. Compare that to Westside Regional Center with a prevelance of 84. Westside is a much more affluent are with a higher proportion of White families.

From the San Diego Union-Tribune: “There is mounting evidence that at least some of this clustering results from the greater access and utilization of services by those with more years of schooling,” the UC Davis researchers wrote.

Yes, there is a certain “I told you so” moment here. This blog, Autism Diva, Autism Natural Variation, Autism Street and others have been pointing out the apparent autism clusters in the raw CDDS data for years. Long before I started blogging. But the real story isn’t the effect such clusters have on the idea of the “autism epidemic”. Rather, this is a clear indication that we are underserving the disabled in our minority and poor communities. This is just plain wrong.

It is long past time for real autism advocacy organizations to work on increasing awareness and access to services in underserved areas. The autism “clusters” are probably not real. From where I sit, what is real are the “anti—clusters” of undiagnosed autistics, minorities, the poor, and, yes, adults.


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