Autism rates among racial minorities in the U.S. have spiked in recent years, with black rates now exceeding those of whites in most states and Hispanic rates increasing faster than any other group, according to a new study published in the Journal of Autism and Developmental Disorders.
The researchers from the University of Colorado Boulder also found that the prevalence of autism among white youth is ticking up again, after flattening in the mid-2000s.
Although some of the increases are due to more awareness and better detection among minority groups, other environmental factors are likely at play, the authors conclude.
“We found that rates among blacks and Hispanics are not only catching up to those of whites — which have historically been higher — but surpassing them,” said lead author Dr. Cynthia Nevison, an atmospheric research scientist with the Institute of Arctic and Alpine Research.
“These results suggest that additional factors beyond just catch-up may be involved.”
For the study, Nevison worked with co-author Dr. Walter Zahorodny, an autism researcher and associate professor of pediatrics at Rutgers New Jersey Medical School, to analyze the most recent data available from the Individuals with Disabilities Education Act (IDEA) and the Autism and Developmental Disabilities Monitoring (ADDM) Network.
IDEA tracks prevalence, including information on race, among 3-to-5-year-olds across all 50 states annually. ADDM tracks prevalence among 8-year-olds in 11 states every two years.
The findings show that between birth year 2007 and 2013, autism rates among Hispanic children, ages 3 to 5, rose 73%, while rates among blacks rose 44% and rates among whites rose 25%.
In 30 states, prevalence among blacks was higher than among whites by 2012.
In states with “high prevalence,” 1 in 79 whites, 1 in 68 blacks and 1 in 83 Hispanics born in 2013 had been diagnosed with autism between ages 3 and 5.
Other states, including Colorado, fell in a “low-prevalence” category, but the authors warn that the differences between states likely reflect differences in how well cases are reported in preschool-age children. They also said the real prevalence is substantially higher, as many children are not diagnosed until later in life.
“There is no doubt that autism prevalence has increased significantly over the past 10 to 20 years, and based on what we have seen from this larger, more recent dataset it will continue to increase among all race and ethnicity groups in the coming years,” said Zahorodny.
In 2018, the Centers for Disease Control reported that about 1 in 59 children of all races have been diagnosed with autism and that rates had risen 15 percent overall from the previous two year period, largely due to better outreach and diagnosis among historically underdiagnosed minority populations.
“Our data contradict the assertion that these increases are mainly due to better awareness among minority children,” said Zahorodny. “If the minority rates are exceeding the white rates that implies some difference in risk factor, either greater exposure to something in the environment or another trigger.”
Risk factors associated with autism include advanced parental age, challenges to the immune system during pregnancy, genetic mutations, premature birth and being a twin or multiple.
The authors said that, based on current research, they cannot determine what other environmental factors might be playing into the higher rates, but they would like to see more work done in the field.
Source: University of Colorado Boulder