Adults with Down syndrome and early stage Alzheimer's disease showed decline in their ability to selectively attend to stimuli in a multitrial cancellation task. They also showed variability in their performance over the test trials, whereas healthy participants showed stability. These changes in performance were observed approximately 2 years…

The authors present a case study of a 70-year-old man with Down syndrome ("Mr. C.") who they followed for 16 years and who does not exhibit declines in cognitive or functional capacities indicative of dementia, despite having well-documented, complete trisomy 21. The authors describe the age-associated changes that occurred over 16 years as well…