A new report using 2014 data suggests that one in 45 children aged 3-17 has autism spectrum disorder in the U.S.
That number is up from one in 80 children in 2011-2013, according to the Centers for Disease Control and Prevention National Center for Health Statistics Nov. 13 report.
A big reason for the increase is a change in the way researchers asked parents questions about their children having autism.
“We believe this increase we saw from previous years of the National Health Interview Survey was the result of three changes we made to the survey in between those years,” said Benjamin Zablotsky, Ph.D., an epidemiologist at the National Center for Health Statistics and lead researcher on the report.
“Those included expanding the wording of the question about autism spectrum disorder, changing the formatting of the question about autism spectrum disorder and changing the position of the question about autism spectrum disorder.”
In the previous survey, the question about autism spectrum disorders was found within a 10-item condition checklist. In 2014, the question was stand alone, asking parents if a doctor or health professional had ever told them that their child had autism, Asperger disorder, pervasive developmental disorder or autism spectrum disorder.
Also, the question about autism spectrum disorder came before a question about other developmental delays in the 2014 survey – another change from the 2011-2013 survey.
“What we saw was a reclassification of parents regarding their children,” said Zablotsky. “In the 2011-2013 survey, parents that had said their child had another developmental disorder would be more likely in 2014 to say their child had autism spectrum disorder.”
According to the report:
- The estimated prevalence of autism spectrum disorder was 2.24 percent (1 in 45) in 2014, while averaging 1.25 percent (1 in 80) from 2011 through 2013.
- The estimated prevalence of other developmental delays was 3.57 percent in 2014, while averaging 4.84 percent from 2011 through 2013.
- The estimated prevalence of intellectual disability did not change significantly between 2011 and 2013 (1.27 percent) and 2014 (1.10 percent).
- Despite changes to the prevalence of autism spectrum disorder and other developmental delay, the overall prevalence of children with either autism spectrum disorder or other developmental delay did not change between 2011-2013 (5.26 percent) and 2014 (5.3 percent).
- The prevalence of children with any of the three conditions (intellectual disability, autism spectrum disorder, or other developmental delay) in 2011-2013 (5.75 percent) and 2014 (5.76 percent) did not differ significantly.
Gagan Joshi, M.D., director for the Autism Spectrum Disorder Program in Pediatric Psychopharmacology, medical director of the Alan & Lorraine Bressler Program for Autism Spectrum Disorder at Massachusetts General Hospital, and assistant professor of psychiatry at Harvard Medical School, said the survey’s new numbers don’t surprise him. “I think it’s expected. In the last decade or so, every study by the CDC has shown the same trend, more recognition of spectrum.”
He says the rise is happening with more recognition of high-functioning autism. “They are on the rise because they are the ones with a backlog of under recognition,” he said.
High functioning individuals dealing with autism are intellectually capable, usually at par or superior to their peers, but deal with social or emotional deficits, Joshi said. Those dealing with low-functioning autism do not seek social interaction and have an intellectual disability.
Prevalence rates of low-functioning autism have remained steady over the years, he said.
Diagnosis of autism is often late in a child’s life, usually recognized by the age of 3½ or 4. High-functioning autism is often diagnosed later, at ages 6-8. “Interestingly, high-functioning autism with emotional behavioral difficulties is recognized even later in 10 or 11 years of age, so by the time we recognize it, we have lost many years that we could have helped the child to work social skills,” he said.
Often, the emotional dysregulation of the disorder masks autism spectrum and these children are often over medicated and aggressively treated for emotional deficits, he said. “One needs to be very sensitive to screen and diagnose [autism] spectrum in the emotionally disturbed population.”
By Rivkela Brodsky