In some U.S. communities autism prevalence is more than three times the national average, a new study suggests.

While the developmental disability is estimated to affect less than 2% of children nationwide, rates in parts of New Jersey are nearly 7% or higher, according to findings published recently in the journal Autism Research.

Researchers took an in-depth look at the number of children with autism in four New Jersey counties that include 76 school districts. They combed special education records and those from hospital-based developmental centers to identify all children born in 2008 who had autism indicators at age 8. Then clinicians reviewed the records to confirm whether a child qualified for a diagnosis on the spectrum. The methodology used is consistent with what the Centers for Disease Control and Prevention employs to come up with national prevalence estimates.

The study found rates of the developmental disability that varied considerably from one place to the next and by other factors including race, socioeconomic status and school district size.

Overall, autism prevalence was 3.6% in New Jersey. But the rate topped 5% in a fifth of school districts, reaching a high of 7.3% in the state’s largest suburban district, Toms River.

“We found that mid-socioeconomic status communities, like Toms River, had the highest ASD rates, which was contrary to expectation because in earlier U.S. studies ASD rates were highest in high-socioeconomic status communities,” said Josephine Shenouda, a project coordinator at Rutgers New Jersey Medical School and a co-author of the study.

Hispanic children were less likely to be diagnosed with autism, the research found.

It’s unclear what’s driving differences in prevalence across communities, but the researchers said it could be due to the level of access to services or it’s possible that families of children with disabilities are inclined to move to certain areas.

Regardless, they said the findings indicate that more work needs to be done to address the needs of children on the spectrum.

“The study suggests that effective educational and health planning should be informed by community and county level estimates and data as well as by state and national averages,” said Walter Zahorodny, an associate professor of pediatrics at Rutgers New Jersey Medical School and a co-author of the study. “It also shows that additional effort is needed to reduce disparities in the identification of ASD in the Hispanic community, including expansion of ASD screening of toddler-age children.”

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