RecruitingPhase 2Drug trialUAB Alzheimer's Disease Center Core Cohort - Imaging SubstudyThe primary objective of this study is to measure the concentration and the regional brain distribution of pathologic amyloid deposition using the PET tracer \[C-11\]PiB in participants in the UAB Alzheimer's Disease Center cohort. Assessment of interactions between race and vascular risk factors, brain amyloid levels measured with \[C-11\]PiB-PET, and cognitive status will be the primary outcome of this imaging study.