Specific Aim 1: To assess and compare amyloid deposition (with PiB PET) in non-demented/functionally stable adults with DS across three age cohorts (30-39, 40-49, and \>50 years of age).
Primary Hypothesis 1: At initial assessment, there will be a significantly higher prevalence of amyloid-positive (PiB+) subjects in each succeeding age cohort.
In addition, we will test the following secondary hypothesis:
Secondary Aim 1: To compare the presence or absence of the apolipoprotein-E4 allele to the retention of PiB in various brain areas of the DS subjects.
Secondary Hypothesis 1: At baseline, subjects who carry at least one Apolipoprotein-E4 (ApoE4) allele will show a higher prevalence of being PiB+.
