California Autism Prevalence by County and Race/Ethnicity: Declining Trends Among Wealthy Whites.
Cynthia Nevison, William Parker
PMID 32193763WHAT IT FOUND
Autism prevalence in wealthy California counties dropped for white children after birth year 2000, while rising in poorer areas.
This suggests high-income families may be opting out of state services or accessing private care, rather than a true decrease in autism rates.
Key findings
01White autism prevalence decreased in wealthy counties like Santa Clara and Marin for birth years 2000–2013, while it continued to rise in lower-income counties.
02Statewide, black children had the highest autism prevalence at 1.8% in birth year 2013, surpassing white, Asian, and Hispanic rates.
03Hispanic autism prevalence increased steadily across all counties from 1993 to 2013, without the plateau or decline seen in wealthy white populations.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study uses aggregated, de-identified data, so individual patient factors cannot be analyzed. Denominators were based on public school enrollment, which may underestimate total population in areas with high private school attendance. DDS data only captures individuals who qualify for and seek state services, missing those who use private insurance or decline services. The study cannot distinguish between a true decrease in autism cases and a decrease in state service enrollment among wealthy families. Birth years after 2008 rely on extrapolated population data, introducing uncertainty in recent prevalence estimates.
Declared interests
The authors declare no conflicts of interest.
The easy way to misread this
Do not interpret the decline in autism prevalence among white children in wealthy California counties as evidence that autism is becoming less common in that demographic. The data likely reflects a shift in where these families seek services, with many opting for private care instead of the state-run DDS program, rather than a true reduction in diagnoses.