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From the archives: What it feels like to be autistic
02:10 - Source: CNN

Story highlights

The percent of children believed to be on the spectrum increased to 2.24%, but the number of children with other disorders fell significantly

Study authors think the change in the way they asked parents about their child's development impacted the number

Autism is incredibly difficult to diagnosis; there is no blood test or swab

CNN  — 

On the surface, it looks like the number of children in the United States whose parents say they have autism spectrum disorder has grown significantly. But this latest study from the National Center for Health Statistics begs a bigger question: Are there really more children with autism, or did the way in which the United States collects that information affect the reportable number?

Read: Vaccines do not cause autism

As of right now, the Centers for Disease Control and Prevention estimates a growing number of children, one in 68, is believed to have an autism spectrum disorder. That’s a 30% increase from estimates in 2012.

Read: ‘Sesame Street’ gets a new character on the spectrum

This latest study looks at data collected in 2014. When they gathered that information, the survey that they gave parents took a new approach to asking about autism and changed the order of the questions. With that switch, the number of children believed to be on the spectrum is 2.24% – that’s 1 in 45 children. That’s a large increase.

Study authors wondered whether the changing survey method has had an effect on the numbers; that’s because the number of children who parents say have another developmental disorder went down significantly. That number fell from 4.84% in 2001-2013 to 3.57% based on 2014 data. That could mean, the authors say, that parents were selecting autism as opposed to another developmental disorder in part because the question about autism comes before questions about those other disorders.

Read: U.S. rate of overdiagnosis

Diagnosing autism is hard. There is no blood test or simple swab. A doctor must look at a child’s behavior and development over time to make that determination.

Showing how tricky that diagnosis is an October study from the Center for Health Statistics found that 13% of children who were labeled autistic lost their diagnosis after later tests. Of the parents who were surveyed about the reversed diagnoses, about 74% thought the reversals were because of new information, meaning their child started to show developmentally appropriate social skills or language abilities, as opposed to a child being “cured.”

So what is it? Can we comfortably say that there are more children with autism?

“We do believe autism is more prevalent, but we have long believed that the 1 in 68 number is an underestimate,” said Michael Rosanoff, the director of public health research at Autism Speaks. But he cautions those numbers are based on solid data including education and medical records.

This latest study relied solely on parent questionnaires and specifically looked at methodology, not numbers. Regardless, he says, “it is time to look beyond the numbers and more important for us to know how many people have access to care and services that can improve their lives.”

Read: How early intervention works

Recent studies have shown that early intervention can help some children.