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Autism rates have risen sharply but unequally among California children, with the steepest increases occurring in lower- and middle-income counties, according to a new study analyzing more than two decades of state data.
The study, published in Sage Open Medicine, analyzed autism cases recorded by the California Department of Developmental Services (DDS).
The researchers identified a marked acceleration in autism spectrum disorder (ASD) diagnoses beginning with children born in the mid-2010s, especially those born in 2016.
The largest increases occurred among Hispanic and Black children in many counties, with the race and ethnicity disparities widening for the youngest of those children.
“The data show that we haven’t even begun to see the tapering off of autism rates,” Children’s Health Defense Senior Research Scientist Karl Jablonowski said. “If there is an end to the autism explosion, we can’t see it yet.”
A ‘changepoint’ in 2016
In January, using the California DDS data, Rutgers University researchers Cynthia Nevison, Ph.D., and Walter Zahorodny, Ph.D., analyzed autism cases recorded between 1993 and 2020.
They examined the 36 most populous counties and separated the data by Asian, Hispanic, Black and white populations, and the population as a whole.
They found that autism prevalence has surged across the state over the past decade, with a striking “changepoint” in 2016, when rates for children born that year began climbing much more rapidly, stratified by race and ethnicity.
The pattern was more evident in lower-income counties. For children born between 2000 and 2014, autism rates in those counties had been rising among both white and Hispanic children. But the rate accelerated after 2015.
For children born in 2020, autism prevalence reached an estimated 8.7% for white children in lower-income Butte County and 4.9% for Hispanic children in Fresno and Tulare counties.
The study also found strikingly high estimates among Black children. In the nine counties with sufficient data for analysis, autism prevalence for Black children was consistently higher than for white, Asian and Hispanic children.
Among Black children in Los Angeles County in 2019, the autism rate approached 9.5%. It reached roughly 8% in Sacramento, Fresno and Kern counties, and approximately 6%-7% in Orange and San Diego counties.
Statewide, DDS data show an estimated autism rate of 3.9% for children born in 2019, compared with 1.5% for those born in 2013.
For children born in 2019, autism rates were highest among Black children (6.0%), followed by Hispanic children (3.4%), Asian children (3.0%) and white children (2.7%).
Nevison told The Defender that the evidence of a change point in many locations across California is “surprisingly crisp.” She said the data is important and should be used by researchers trying to determine why California autism rates are so high and show such significant demographic divergence.
The data also support anecdotal evidence from California teachers who report worsening situations in autism learning centers in public schools, she said.
Teachers told Nevison that more students are exhibiting more challenging behaviors, teachers are suffering burnout, and as a result, schools face staffing issues.
“The data in my paper suggest that the perception of my teacher friends is correct,” Nevison said.
She added:
“ASD prevalence is growing and increasingly the students who are most severely affected are those whose families are least able to cope or afford nutritious food and other health-promoting therapies.
“I think this underscores the need to engage with the public schools and to ask teachers what they are seeing in the classroom and to take the situation seriously and do something to help these kids.”
‘You may be in for a shock in the next few years’
The study did not address the possible causes of the rising rates, but they said the timing and the magnitude of the acceleration warrant further investigation.
The researchers said the change point around 2016 was particularly notable when the change was broken down by county, whereas statewide estimates tend to obscure it.
“Understanding the factors driving diagnosed ASD prevalence up to the high levels reported in this study is a pressing public health concern,” they concluded.
Jablonowski said “a pressing public health concern” is academic-speak for “we’re destroying the neurological health of our children at epidemic proportions, and we don’t know (or don’t acknowledge) how and why.”
He added:
“If you haven’t been paying attention, you may be in for a shock in the next few years. One scenario is that civilization collapses under the weight of our autistic future. Drastic measures are required: some will quibble, some will act.”
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Nationally, pool of children susceptible to autism appears to be growing
Researchers increasingly agree that autism results from “a complex interaction of genetic factors and early environmental insults,” according to the paper.
These interactions can cause neuroinflammation, immune dysregulation and oxidative stress, culminating in brain injury in young children during critical stages of neurodevelopment, the authors wrote.
The pool of children susceptible to these factors appears to be growing.
The Centers for Disease Control and Prevention’s (CDC) Autism and Developmental Disabilities Monitoring (ADDM) Network tracks autism rates at 16 sites across the country to provide a national snapshot of autism rates.
Every two years, the ADDM publishes a report, tracking ASD rates among 8-year-olds and 4-year-olds. The most recent report found a mean ASD prevalence of 1 in 31 (i.e., 3.2%) of 8-year-olds who were born in 2014.
Since 2021, when the CDC added a site in San Diego to the list of ADDM sites, California has consistently recorded the highest autism rates among all U.S. locations. In the last report, California reported autism rates of 5.31% in 8-year-olds born in 2014, and 6.06% in 4-year-olds born in 2018.
Based on comparisons with federal surveillance data from the ADDM, Nevison and Zahorodny estimated that California’s DDS data may identify only about half of all autism cases — significantly underestimating the true scope of autism.
Jablonowski said it was notable that the often-cited statistic that 1 in 31 U.S. children are diagnosed with autism comes from the CDC’s data based on children born in 2014.
“The changepoints identified in this new study are predominantly post-2014. Since 2014, autism rates have continuously and drastically climbed, according to the more up-to-date California DDS data,” he said.
Related articles in The Defender
- 1 in 31 Kids Had Autism in 2022 — Up From 1 in 36 in 2020
- ‘Genes Do Not Cause Epidemics’: Kennedy Lambastes Media for Denying Autism Epidemic, Vows to Research Environmental Triggers
- Autism Prevalence: A Real, Accelerating Epidemic
- ‘Autism Tsunami’: Society’s Cost to Care for Expanding, Aging Autism Population Will Hit $5.54 Trillion by 2060
- In New Autism Report, CDC Again Fails to Address Root Causes
