More than one in 50 American children have been diagnosed with a disorder on the autism spectrum, according to a new paper published in JAMA on Tuesday, in a finding that suggests diagnoses of the condition have leveled off. The new research also shows that the disorder continues to be more frequently diagnosed in white children than among non-white children.
About 2.7 percent of non-Hispanic, white children have been diagnosed with autism, Asperger's syndrome or another developmental disorder on the spectrum. Only 1.8 percent of Hispanic children and 2.3 percent of black children have autism spectrum disorder diagnoses; the national rate is 2.4 percent. The researchers used data from the National Health Interview Survey for their analysis; all other racial or ethnic groups were included in a fourth category.
The rate of autism spectrum diagnoses among all children did increase a bit each year between 2014 and 2016; however, these increases were not considered statistically significant. This is the first time in more than a decade that the rate has plateaued.
Autism spectrum disorder is a category that includes diagnoses like autism and Asperger syndrome. Rather than being diagnosed separately, these two conditions, and another known as pervasive developmental disorder, not otherwise specified, are all grouped together. Symptoms of conditions on the spectrum can range, but children with ASD generally interact and communicate with others in ways that are considered unusual.
Racial disparities in autism diagnoses have already been well-studied. One study published in November in the American Journal of Public Health also found similar disparities and broke down prevalence trends by socio-economic indicators. The authors compared the rates of autism diagnoses in a given neighborhood to the percentage of adults living there who had graduated college. More children were diagnosed with autism spectrum disorders in neighborhoods where more than a third of the adults living there had a bachelor's degree.
Maureen Durkin, one of the authors of that study and a population health researcher at the University of Wisconsin School of Medicine and Public Health, told Spectrum that differences in socio-economic status may be one reason why children who are black and Hispanic are less likely to get screened for autism spectrum disorders—leading to relatively lower diagnosis rates.
However, it's impossible to say for sure if black or Hispanic children aren't being diagnosed with autism as frequently as white children because they don't have the same access to diagnostic services. "It is complicated, and we can't say for sure. I would love to say that we know exactly why, but we can't," she told Newsweek.
"We've been following this issue of a social class gradient in autism for a long time," Durkin said. Economic factors—being able to afford the assessments and services associated with an ASD diagnosis—are likely the main factor, she said.
Racial discrimination and economic inequality are linked, too—but Durkin and her colleagues have found that the rates of diagnoses differ between white children and other children in the same socio-economic class. (There is one exception, she noted; children in the highest socio-economic class are diagnosed with autism at about the same rate, regardless of race.)
It's still not clear what else might be leading to the different rates of diagnoses, she told Newsweek. Whatever is behind the inequality, it seems to be uniquely American; in countries like Sweden and France, Durkin noted, these racial differences don’t seem to exist.