Age, adaptive behavior, and Alzheimer disease in Down syndrome: cross-sectional and longitudinal analyses.

Cross-sectional and longitudinal analyses were used to compare age-related changes in adaptive functioning in institutionalized adults with and without Down syndrome. Cross-sectional analysis showed significant differences related to level of functioning but not to age or etiology of disability. Longitudinal analysis showed a pattern of decline in self-help and communication skills in several individuals with Down syndrome older than 40. The case of an adult with Down syndrome with confirmed Alzheimer pathology at postmortem was presented. Results were discussed in relation to aging and the likelihood of Alzheimer-like changes in individuals with Down syndrome.