Higher education

University of Iowa analysis finds autism diagnoses more prevalent than reported

'This should cause us to reconsider' research, service, and policy priorities

Seven-year-old Gabriel Marchini of Iowa City was diagnosed with autism in 2016. Photographed at his home in Iowa City on
Seven-year-old Gabriel Marchini of Iowa City was diagnosed with autism in 2016. Photographed at his home in Iowa City on Friday, January 1, 2018. (Cliff Jette/The Gazette)

IOWA CITY — Significantly more American children are diagnosed with autism spectrum disorder than previously thought, according to a new and more comprehensive analysis out of the University of Iowa published this month in the Journal of the American Medical Association.

Where the Autism and Developmental Disabilities Monitoring Network in 2012 reported a plateau in autism prevalence at 1.46 percent of American children, or 1 in 68, the new UI analysis of data from the U.S. Centers for Disease Control and Prevention suggests 2.4 percent of American children ages 3 to 17 — or 1 in 41 — have an autism diagnosis.

Autism is a neurodevelopmental disorder characterized by a spectrum of deficits in social interactions and communications, restricted behavior and repetitive patterns that can burden individuals, families and communities.

Adriana Marchini of Iowa City said her seven-year-old son Gabriel was diagnosed in 2016 — at age 6 — and she was glad to have the confirmation and resulting treatment after years of challenging behavior.

“I think it’s made a difference in the sense that when you have a child with bad behavior and you are not able to control it, you are feeling like a bad mom,” said Marchini, whose family moved to the area from Brazil.

“You cannot understand. But when you have the diagnoses, you understand better what is happening with your child.”

Before reporting a plateau in 2012, the autism monitoring network noted a rise in autism prevalence, from .67 percent in 2000 to 1.47 in 2010. A National Health Statistics Report in 2015 suggested numbers might be higher after 2014 changes to questions in the National Health Interview Survey.


But because the question changes were so recent, limiting the survey’s ability to analyze trends, UI researchers wanted to review a longer period of data — from 2014 to 2016. Their findings suggesting more diagnoses begs the question of why — whether awareness or an actual rise in prevalence is to blame.

Part of the increase in autism spectrum diagnoses likely is tied to differences in data collection, as the Autism and Disabilities Monitoring Network uses health and special education records of 8-year-olds at 11 select sites while the UI analysis looked at data for 3- to 17-year-olds nationally.

That national health survey data incorporates findings from thousands of in-person interviews, including questions of whether a child in the household has ever been diagnosed with autism. The data is limited in that it relies on self-reporting, according to Wei Bao, assistant professor of epidemiology in the UI College of Public Health and corresponding author of the analysis.

“Previous thinking about autism is that it is very rare, but this study tells us that it is no longer something that is very rare,” Bao said on a UI website. “This should cause us to reconsider what our future priorities in research, service and policy should be regarding children who have autism spectrum disorder. Clearly, we need more people to care for children with autism.”

At the UI autism center, for example, demand to be seen — and thus the wait — has been growing in recent years, according to analysis co-author Lane Strathearn, professor of pediatrics in the UI Carver College of Medicine and director of the Division of Developmental and Behavioral Pediatrics, which oversees the UI Stead Family Children’s Hospital Autism Center.

His clinic right now receives about 70 referrals for evaluation a month — or 825 in the past year. That is up from about 60 a month two years ago.

“We are really swamped with patients,” Strathearn said.

The wait to be seen is between four to five months, with nearly 300 folks on a waitlist, according to Strathearn. Thus, regardless of the reason for the increase in diagnoses, more resources are imperative.

“We’ve seen some progress,” Strathearn said. “But we have a long way to go yet.”


Research has shown that early intervention can help socialize children with autism, which is why Strathearn said his clinic is trying to prioritize younger children seeking evaluation. In addition, professionals are becoming more adept at early diagnoses.

“The screening tools we use are commonly used at 18 and 24 months,” he said, noting Emory University in Atlanta is conducting groundbreaking work finding differences as early as six months.

Earlier assessments might be another reason diagnoses are up, along with heightened awareness of the disorder and parental education, according to Strathearn. But the university is digging into the “why” question right now, conducting a follow-up study asking mothers across Iowa to track their pregnancies and infant behaviors.

Past research suggests both genetics and environmental factors play a role in autism diagnoses — and Bao pointed to one of his own previous studies showing children are at greater risk of autism if their mothers had diabetes before or during pregnancy.

Because diabetes often is linked to obesity, according to Bao, the increase in autism could be tied to a heavier American populace.

Studies also have identified preterm labor as an autism risk factor, and higher levels of stress in a mother or in a family have been associated with autism diagnoses. Researchers have found genetic markers can explain “a tiny proportion of all kinds of autism,” Strathearn said.

“There are hundreds of markers that each explain a tiny bit of risk,” he said. “But nothing that explains the whole picture.”

Although there is “not an autism gene that causes autism,” the UI data analysis did confirm earlier findings about gender and racial or ethnic disparity of autism in American children. Boys are much more likely to be diagnosed than girls — 3.54 percent compared with 1.22 percent. Autism is less common in people of Hispanic origin, 1.78 percent, than in non-Hispanic whites, which report a 2.71 percent prevalence, or non-Hispanic blacks, reporting a 2.36 percent prevalence.


Autism diagnoses are most prevalent in the Northeast, at 3.05 percent, followed by the Midwest at 2.47 percent, the West at 2.24 percent, and the South at 2.21 percent.

Marchini said her son has received numerous forms of treatment since his diagnoses — including changing schools to one with more specialized programming for kids with autism. All that has helped, and she believes it will continue to do so as he ages.

“His teachers are awesome,” she said.

l Comments: (319) 339-3158; vanessa.miller@thegazette.com

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