Aging in adults with Down syndrome: report from a longitudinal study.

Changes in functioning related to aging were examined in 34 adults (14 females, 20 males) with Down syndrome who were 22 to 56 years of age. Changes in functioning over 3 to 4 years were examined, with age, IQ at entry into the study, and gender considered. Neither effects of age at entry nor change over time were significant, suggesting that changes related to aging in adults with Down syndrome were minimal. In contrast, IQ at entry had a significant effect on all performances, suggesting that any examination of aging must consider intellectual level. Results do not support the idea that adults with Down syndrome show rapid age-related declines in functioning apart from the occurrence of a progressive dementia such as Alzheimer's disease.