The LEARN study is a multicenter, observational study that will evaluate the rate of cognitive change in approximately 500 clinically normal older individuals who do not meet the eligibility criteria for enrollment in the A4 trial based of their screening PET imaging not demonstrating evidence of elevated amyloid accumulation (AÎ² negative) but meet all other A4 study eligibility criteria. This study will leverage the A4 infrastructure and maximize the data acquired in screening a large number of well-characterized older adults for the A4 trial.
MRI scans will be used to identify the number of hemosiderin deposits (definite microhemorrhages or areas of superficial siderosis); or any amyloid-related imaging abnormalities – edema/effusions (ARIA-E) at the first visit of the study. The study consists of 8 visits over 3 years. A second MRI exam will be performed at the 8th visit for comparison to the MRI exam performed at the first visit.