A new study is among the first to estimate the number of adults in the U.S. with intellectual disability, offering policymakers and other stakeholders a snapshot of the need for resources.

Just shy of 1% of adults between the ages of 21 and 41 have intellectual disability, according to findings published recently in the Journal of Intellectual Disability Research.

With no national survey measuring prevalence of intellectual disability among adults, researchers turned to data collected on children through the government’s National Health Interview Survey between 1980 and 1999.

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“Intellectual disability is diagnosed in childhood,” said Teal Benevides, an author of the study and an assistant professor at the Institute of Public and Preventive Health at Augusta University. “It needs to be diagnosed early. It’s not something that just happens in adulthood. So relying on the estimate that’s from childhood surveys is a good start.”

When the researchers aged up estimates based on the current U.S. population, they concluded that there were 818,564 people ranging in age from their early 20s to early 40s living with intellectual disability in this country in 2021, or a prevalence of 0.95%.

Importantly, many adults with intellectual disability are on waiting lists for community-based services and are not receiving necessary supports for housing, employment and much more, Benevides said. In addition, they often face an uncertain future as caregivers age.

“What alarms me is we don’t have sufficient services and supports for adults. We just don’t have them,” Benevides said. “When people ask for services, support and resources, there’s no place to point them to unless they are children.”

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