Prevalence of intellectual disability among adults born in the 1980s and 1990s in the United States.
T W Benevides, B Datta, J Jaremski and 1 others
PMID 38234197WHAT IT FOUND
Researchers estimated that 818,564 adults aged 21 to 41 years in the United States have intellectual disability.
This represents a prevalence of 0.95%. These figures provide a necessary denominator for tracking adult health services and planning care resources.
Key findings
01The estimated prevalence of intellectual disability among US adults born between 1980 and 1999 was 0.95%, corresponding to approximately 818,564 individuals aged 21 to 41 years in 2021.
02Prevalence rates were generally higher among males (0.83% to 1.25%) than females (0.62% to 0.95%), though this difference was not statistically significant for the 1980-1984 and 1985-1989 birth cohorts.
03The study relied on parent-reported diagnoses from childhood surveys, which were not confirmed by clinical evaluation, and excluded institutionalised individuals, potentially leading to underestimates.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The estimates rely on parent-reported diagnosis from childhood surveys, which introduces the possibility of recall bias and misclassification. The diagnosis was not confirmed by a clinician or through medical records, so the accuracy of the ID status depends on the parents' understanding and the original provider's assessment. The survey sample excluded individuals who were institutionalised or in the US military, which likely leads to an underestimation of the true prevalence. The study did not adjust for mortality or migration when projecting childhood prevalence into adulthood, which could affect the accuracy of the adult estimates. The findings apply only to adults born between 1980 and 1999 (aged 21-41 in 2021) and do not extend to older adults or those born outside this window.
Declared interests
One author (T. Benevides) is an unpaid member of the Scientific Advisory Board of the Organization for Autism Research and an unpaid Advisory Council member of the Institute for Exceptional Care. The same author has received payment for speaking, travel, and research consulting from various universities and the Institute for Exceptional Care. No other authors declared financial or material conflicts of interest.
The easy way to misread this
Do not interpret these prevalence figures as confirmed clinical diagnoses for individual patients. The estimates are derived from parent reports collected during childhood and projected into adulthood without clinical verification, meaning they represent a population-level approximation rather than a validated diagnostic rate.