The prevalence of autism in 4-year-old children in the United States has increased — from about 1 in 75 children in 2010 to 1 in 59 in 2014 — to match a previously reported rise in 8-year-old children, according to data released last week by the Centers for Disease Control and Prevention (CDC)1.
But children are still being evaluated for autism or other developmental conditions later than is ideal, the data suggest.
The trend highlights how difficult it is to diagnose autism in young children, experts say; early diagnosis is important so that children can be treated early.
The autism prevalence they identified among 4-year-olds in 2014 matches the prevalence among 8-year-olds that same year. (The two groups are not directly comparable, however, because the sites in the two studies don’t match up.)
The new study also shows some of the trends in variability among sites: the Missouri site has the lowest prevalence for 2014, at about 1 in 104 children, and the New Jersey site has the highest, at 1 in 35.
The prevalence in New Jersey increased significantly from 2010 to 2014, whereas the numbers remained stable in Arizona and Missouri.
There is no biological reason for the prevalence to vary so dramatically across the U.S., says Walter Zahorodny, associate professor of pediatrics at Rutgers New Jersey Medical School, who led the analysis for New Jersey.
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