Profound Autism Prevalence and Assessment Practices in a Population-Based Study

Profound autism is a proposed subcategory of autism including individuals unable to meet basic daily adaptive needs and requiring 24-hour care. This report describes documented assessment practices and profound autism prevalence derived using different definitions.

Among 7,084 8-year-old children with autism from a population-based surveillance program in 13 US sites in 2022, we calculated the availability of IQ, verbal status, and adaptive data. We imputed missing data to calculate profound autism prevalence using the "updated" (2025) definition, which includes having 1) either an intellectual quotient (IQ) score <50 OR being nonverbal/minimally verbal AND 2) adaptive functioning significantly below age level (≤70). We compared prevalence using the updated definition to using the "prior" (2021) profound autism definition that did not incorporate adaptive scores, the updated definition with higher IQ score cutoff (≤70), and using only nonverbal/minimally verbal status and adaptive ≤70.

Among children with autism, 61.1% had IQ data, 74.0% had verbal status data, and 55.9% had adaptive data available. Cognitive data (IQ or verbal status) and adaptive data were available to determine profound autism status for 54.4%. After imputation, updated definition profound autism prevalence was 5.4 (95% CI: 5.1-5.8) and nonprofound autism prevalence was 27.5 (95% CI: 26.8-28.1) per 1,000 8-year-olds in 2022. Of children with autism, 16.5% met the updated profound autism definition and 32.1% met one element of the definition but did not meet full criteria. Prevalence was 33.5% higher using the prior definition, 70.9% higher using the updated definition with higher IQ score cutoff, and 33.3% lower using only nonverbal/minimally verbal status and adaptive ≤70.

Prevalence of nonprofound autism was higher than profound autism. Adaptive or other assessments underlying the profound autism definition were missing almost half the time. Community evaluation practices and the profound autism definition can evolve to better understand and meet needs of individuals with autism.