By Lisa Rapaport
After steadily climbing for two decades, the proportion of U.S. children with autism may be leveling off, a recent study suggests.
As of 2016, approximately 2.8% of U.S. children from 3 to 17 years old had autism spectrum disorders (ASD), researchers report online January 2 in JAMA. While that’s up slightly from about 2.2% in 2014, the difference is too small to rule out the possibility that it was due to chance.
Over the three-year study period, about 2.4% of children and teens had ASD, a collection of diagnoses that can include Asperger’s syndrome, autism and other developmental disorders that impact communication and behavior.
That’s higher than previously thought, although the current study mirrors other recent research suggesting autism rates may have hit a plateau, said senior author Dr. Wei Bao, a public health researcher at the University of Iowa in Iowa City. Three years just isn’t long enough to confirm whether autism rates are leveling off, and more time is needed to verify this trend, Bao said by email.
“At this time, it is not safe to conclude firmly that autism rates are no longer rising,” Bao added.
A steady rise in awareness and screening for autism in recent decades is partly responsible for increases in diagnosis rates, the researchers note.
Many pediatricians do routine autism screenings of children between 18 and 30 months old. Screening isn’t universal, however, and the U.S. Preventive Services Task Force (USPSTF) concluded in 2016 that it’s impossible to know if routine screening is warranted.
Early symptoms of autism can vary, but may include repetitive behaviors like hand flapping or body rocking, extreme resistance to changes in routine, and sometimes aggression or self-injury. Behavioral, educational, speech and language therapy may help reduce the severity of autism symptoms in some children.
Autism is more common in boys, and the current study findings offered fresh evidence of this: 3.6% of boys had this diagnosis, compared with 1.3% of girls.
The study also found differences based on race and ethnicity: 1.8% of Hispanic children had autism, compared with 2.8% of white kids and 2.5% of black youth.
Lower diagnosis rates for Hispanic children and for girls might be partly explained by cultural biases, and not necessarily a lower risk of autism for these children, said Dr. Jeremy Veenstra-VanderWeele, a psychiatry researcher at Columbia University in New York City who wasn’t involved in the study.
There might be more Hispanic children diagnosed with autism or less of a gap in autism rates between boys and girls when all children are screened, regardless of whether parents, teachers or doctors voice a concern about a child’s development, Veenstra-VanderWeele said by email.
One limitation of the study is that it relied on data from the National Health Interview Survey, which determines autism diagnoses based on parents responses to questionnaires rather than from medical records or a confirmed diagnosis from a physician.
Whether or not autism rates are truly leveling off, parents still need to understand that it’s a common developmental disorder and make sure pediatricians screen children by the time they’re 18 to 24 months old, said Geraldine Dawson, director of the Center for Autism at Duke University in Durham, North Carolina.
“This can be done with a simple questionnaire that can be filled out in the pediatrician’s office,” Dawson, who wasn’t involved in the study, said by email. “Early treatment makes a difference.”
If autism rates stop rising, it may become easier for kids to get this treatment, said Dr. Craig Powell, a psychiatry researcher at the University of Texas Southwestern Medical Center who wasn’t involved in the study.
“Finding qualified experts for ongoing therapy is not always easy,” Powell said by email. “If ASD prevalence has stabilized, that will make it somewhat easier for communities to rise to the occasion and provide services.”
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