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Rates of autism continue to rise, new data indicate

Many children still diagnosed late, after age 4

by Jim DrydenApril 26, 2018

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New statistics indicate rates of autism in children have continued to increase. However, the rates have increased only modestly, suggesting  there may be a leveling off.

Still, researchers found that many children aren’t getting diagnosed until age 4 or older. The older a child is at diagnosis, the harder it is for health-care professionals to intervene and change the trajectory of autism spectrum disorder. Children with autism often face social challenges, communication problems and intellectual deficits, but research suggests some of those hurdles may be overcome with early, intensive therapy.

The new statistical findings, from the 11-center Autism and Developmental Disabilities Monitoring Network, which includes Washington University School of Medicine in St. Louis, are based on data from more than 10,886 children. The results are published April 27 in the Centers for Disease Control and Prevention’s “Morbidity and Mortality Weekly Report.”

In 2014, the most recent year for which comprehensive statistics are available, researchers found that 1.7 percent of 8-year-olds (1 in 59) in the study had a diagnosis of autism spectrum disorder. That compares with 1.5 percent (1 in 68) in 2012. This increase could indicate an improvement in the identification of autism spectrum disorder, particularly in previously underdiagnosed minority populations, among other factors. Prevalence estimates in the 11 communities represented in this report ranged widely, from a low of 1.3 percent to a high of 3 percent.

“I think this shows that the prevalence of autism in the U.S. is continuing to show signs of steadying,” said John N. Constantino, MD, one of the study’s authors and the Blanche F. Ittleson Professor of Psychiatry and Pediatrics at Washington University. “Unfortunately, however, it appears many kids still aren’t getting diagnosed early enough to get maximum benefit from therapy.”

Some 39 percent of the children in the study who were diagnosed with an autism spectrum disorder didn’t receive such a diagnosis until they were over 4 years of age, added Constantino, director of the William Greenleaf Eliot Division of Child & Adolescent Psychiatry and co-director of Washington University’s Intellectual and Developmental Disabilities Research Center.

“It remains a priority to diagnose autism earlier and begin intervention sooner, especially given recent research suggesting that higher intensity and duration of early developmental therapy for children with autism is associated with significant improvements in outcomes,” he said.

A higher percentage of white children than African-American and Hispanic children were identified as having autism spectrum disorder. That gap, however, is narrowing, which may be due in part to increased efforts to diagnosis children in minority communities.

Despite the narrowing gap, minority children with autism are disproportionately affected by intellectual disabilities related to the disorder. Some 44 percent of African-American children with autism also have intellectual disabilities, compared with 22 percent of white children with the disorder.

“That underscores the necessity of resolving racial disparities in access to diagnostic and therapeutic services,” Constantino said.

In 2004, the Centers for Disease Control and Prevention launched the “Learn the Signs. Act Early” campaign. Its aim is to help identify developmental concerns early so that parents and health professionals are able to intervene to address potential problems as soon as possible.

Baio J, et al. Prevalence of Autism Spectrum Disorder among children aged 8 years — Autism and Developmental Disabilities Monitoring Network, 11 sites, United States, 2014. Morbidity and Mortality Weekly Report, vol. 67 (6), April 27, 2018.

This work was supported by the U.S. Centers for Disease Control and Prevention.

Washington University School of Medicine’s 1,300 faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is a leader in medical research, teaching and patient care, ranking among the top 10 medical schools in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.

Jim retired from Washington University in 2023. While at WashU, Jim covered psychiatry and neuroscience, pain and opioid research, orthopedics, diabetes, obesity, nutrition and aging. He formerly worked at KWMU (now St. Louis Public Radio) as a reporter and anchor, and his stories from the Midwest also were broadcast on NPR. Jim hosted the School of Medicine's Show Me the Science podcast, which highlights the outstanding research, education and clinical care underway at the School of Medicine. He has a bachelor's degree in English literature from the University of Missouri-St. Louis.