Increasing Autism Diagnostic Rates in California

Last updated on July 26, 2026

Is autism increasing or are the diagnoses increasing? I presume we’re getting better at diagnosing autism.

Autism in California increases twelvefold

By Sandy Kleffman
Updated: 05/06/2009 08:12:02 PM PDT

California saw a twelvefold increase during the past two decades in the number of autistic people who are receiving services through regional centers, a new state study reveals.

Notice this is the number of people receiving services. This may or may not reflect an increase in autism diagnoses, a decrease in social stigma, or other factors. Also, in a slower economy, more people seek public assistance.

From 1987 to 2007, the number of children and adults with autism served by regional centers rose from 2,701 to 34,656, notes a study released this week by the state Department of Developmental Services.

This is a huge increase, but I would like to know the percentage increase. I realize that California did not double in population, so no matter what this is an exponential increase in autism services. Still, will read the full report to compare percentage increases to those in other states. The differences in service rates should be interesting to analyze.

The article does indicate only the most disabling forms of autism were counted. This means that the increase is not reflective of the surge in Asperger’s diagnoses.

The statistics include only people who are receiving services through regional centers, which represents about 75 to 80 percent of the autistic population, the study estimates.

The numbers also include only those with classic autism. For the most part, people with other autistic spectrum disorders, including Asperger’s syndrome and Rett’s Disorder, are excluded from the statistics

I wonder what the data mean, if anything at all.