THURSDAY, April 26, 2018 (HealthDay News) -- Autism rates continue to climb in the United States.
About 1.7 percent of children -- one in 59 -- are now believed to have autism spectrum disorder, up from an estimated rate of 1.5 percent in 2016, according to data from the U.S. Centers for Disease Control and Prevention.
The CDC said Thursday that some of the increase comes from better identification of autism cases in minority populations.
"Autism prevalence among black and Hispanic children is approaching that of white children," said Dr. Stuart Shapira, associate director for science at the CDC's National Center on Birth Defects and Developmental Disabilities.
"The higher number of black and Hispanic children now being identified with autism could be due to more effective outreach in minority communities, and increased efforts to have all children screened for autism so they can get the services they need," he added in an agency news release.
Autism is a developmental disorder characterized by repetitive behaviors, and challenges with social skills and communication.
But autism experts said better detection is not solely responsible for the continued increase in autism rates.
"We are seeing an increase, and I think it's a meaningful increase," said Thomas Frazier, chief science officer for Autism Speaks, an autism advocacy organization. "I don't think this increase can be completely accounted for" by the closing of disparity gaps.
The CDC's monitoring estimates are based on observations from 11 communities in Arizona, Arkansas, Colorado, Georgia, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Tennessee and Wisconsin. The researchers looked at more than 325,000 children who were 8 years old in 2014.
Overall, the researchers found that about one in 59 of these 8-year-olds had been diagnosed with autism in 2014, up from one in 68 in 2012.
The new estimate means that autism rates have more than doubled since 2000, the researchers reported.
Autism estimates varied widely among the 11 communities in the new report, although five reported similar estimates of 1.3 percent to 1.4 percent. The highest estimate of 2.9 percent came from a community in New Jersey.
The findings were published in the April 27 issue of the CDC's Morbidity and Mortality Weekly Report.
The report shows that doctors are doing a better job of detecting autism, Frazier said.
"Certainly, we're seeing a closing of disparities. White children are being identified at similar rates now as African-American children," Frazier said. "There's still a little bit of a discrepancy with Hispanic children, but at least those disparities are closing."
But Frazier believes other factors are at work.
"We definitely need more research into what's driving this prevalence increase," he added.
The researchers said they can't explain why autism rates have been increasing across the United States. Factors associated with a higher risk of autism include having parents older than 30, maternal illness during pregnancy, genetic mutations, birth before 37 weeks' gestation and a multiple birth.
According to Walter Zahorodny, an associate professor of pediatrics at Rutgers New Jersey Medical School, "These are true influences that are exerting an effect, but they are not enough to explain the high rate of autism prevalence." Zahorodny directed the New Jersey portion of the study.
"There are still undefined environmental risks which contribute to this significant increase, factors that could affect a child in its development in utero or related to birth complications or to the newborn period. We need more research into non-genetic triggers for autism," Zahorodny said in a Rutgers news release.
Frazier added that he's concerned by findings in the report that show autism is not being detected early enough in many children.
About 40 percent of the children in the study didn't receive their first autism diagnosis until they were over 4 years old, even though most had already shown some signs of the disorder, the report found.
About 85 percent of children with autism had concerns about their development noted in their health records by the time they were 3, the researchers found. Despite this, only 42 percent received a developmental evaluation by that age.
"We still need to do a much better job at early identification," Frazier said. "There are too many kids being identified after age 4. You're talking about losing months if not years of early intervention. We should be identifying kids closer to 2."
The report also indicated a need for better programs to help low-functioning children with autism, said Alison Singer, president and co-founder of the Autism Science Foundation.
"It's important to note that one-third of the children identified with autism also had intellectual disability," Singer said. "These are the children we don't see on TV shows, or advocating for themselves in Washington. We need to make sure we use the new data to create programs and services that serve the needs of this segment of the autistic population."
Learn more about autism spectrum disorder from the U.S. National Institute of Neurological Disorders and Stroke.