For the study, the researchers analyzed 20 years’ worth of autism caseload counts from the California Department of Developmental Services, comparing data from 36 of the state’s most populous counties.
Between birth years 1993 and 2000, autism prevalence increased steadily among all racial groups.
But around 2000, the trajectories started to diverge: Prevalence among whites in wealthy counties like Santa Clara (home to Silicon Valley) and from Monterey to the San Francisco coast started to decline.
In middle-income counties like Sacramento, Los Angeles and San Diego, prevalence among whites continued to increase, but at a slower rate.
Meanwhile, in lower income areas like Riverside and the South Central Valley, rates among whites climbed steeply.
By birth year 2013, prevalence among whites in the lowest income counties was at least double that of whites in the highest income counties. Generally speaking, the higher the county income, the lower the rate of autism among white children.
Read mere here.
