The LEARN study a multicenter, observational study will that will evaluate the rate of cognitive change in approximately 500 clinically normal older individuals who "screen-fail" for the A4 trial on the basis of their screening PET imaging not demonstrating evidence of elevated amyloid accumulation (Aβ 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.
The LEARN observational cohort will provide a critical comparison group for the A4 placebo arm, and future trials in preclinical AD. Although accumulating longitudinal data suggest that older individuals with elevated Aβ burden are at increased risk of cognitive decline, it is important to demonstrate a differential rate of clinical decline between Aβe ("Aβ elevated") and Aβne ("Aβ not elevated") individuals on a standardized set of clinical outcomes. Over 2000 well-characterized, highly motivated older volunteers will "screen fail" for the A4 trial. The LEARN study will follow 500 of these individuals, matched as closely as possible to the two treatment arms, in this observation cohort. The LEARN study may selectively recruit from a specific range of SUVr that fall below the threshold for "elevated amyloid" in order to support analyses of the relationship of baseline SUVr to subsequent cognitive change and amyloid accumulation. The observational cohort will be followed for 384 weeks with identical clinical/cognitive testing performed every 24 weeks, running parallel to the A4 treatment study and open label extension.
Longitudinal Evaluation of Amyloid Risk and Neurodegeneration - the LEARN Study. A Companion Observational Study to Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) Trial