Amyloid Plaque and Tangle Imaging in Alzheimer's Disease and Down Syndrome

This is a naturalistic study in which clinical evaluations and brain scans will be performed on 20 people with Down syndrome (DS) as well as 20 healthy controls across a range of ages. Participants will receive comprehensive clinical and neuropsychological assessments. PET and MRI scans will be performed at baseline and after two years of follow up. All participants will have blood drawn for APOE genotyping during their baseline evaluations. The intellectual range of participants with DS will be restricted to IQ scores of 45 to 60 (moderate range) to reduce variability, particularly due to extreme low levels of intellectual ability.