ScopeDetection of Disease-Related Changes in Pre-Symptomatic Alzheimer's Disease

We will take pictures of subjects' brains using PET imaging, in healthy older adults (ages 55 to 80 years) who have both a family history of AD, and who have concerns about changes in their memory (but no clinical symptoms of AD), to see how much of a protein - that is related to AD -is in their brains. When all subjects come to the hospital for PET imaging, we will review the entire study plan with them, the risks and benefits of participation, and we will obtain written informed consent at that time. Our goal is to compare performance on our new stress test to these PET imaging results. Once the PET imaging is done, we will have each subject come to our clinical research unit for a day-long baseline visit. In the morning we will give the tests of memory and thinking, and then we will administer the injection of scopolamine at a very low dose. We will then continue to examine the subjects, and to give the memory and thinking tests at 1, 3, 5, 7, and 8 hours post-dosing. Once they have fully-recovered from all effects of the medication, they will be allowed to go home that day. We will then see all subjects again, for much shorter visits to complete the cognitive tests, at both 9 and 18 months after their initial study visit. We will follow all subjects for 18 months to see which of them show very mild but measurable changes on the memory and thinking tests, as we predict that these will be the same persons who also had stronger results on our stress test at the first study visit. At all three study visits to our clinical research unit, we will obtain measurements using an imaging device that uses infrared and blue light to take picture of the eye and retina. Our secondary goal in this study to search for evidence of the same protein, in the retina, that builds up and is seen with PET imaging of the brain in persons who are at high risk for AD. Finally, we are also collecting a small sample of saliva, at the first visit to our unit, in order to see which subjects have a genetic risk for the disease, as this genetic risk may affect how we interpret the results of our new "cognitive stress test". In this study, a small dose of an already approved medication (used to treat seasickness) will be used to temporarily, and safely, mimic signs of very early disease during just the first day of testing. This is a methodological study to determine if tests that measure how you think can predict the risk of dementia as we age.