Clinical Core Summary/Abstract The Clinical Core of the Program Project Grant (PPG) has provided clinical, cognitive and cognitive diagnostic adjudications, and coordinated autopsies for the past three cycles of the PPG. For the 4th cycle of the PPG (PPG4), the Clinical Core continues this crucial responsibility providing clinical and cognitive diagnostic classifications that are critical to the aims and hypotheses of the Projects. The Clinical Core is primarily responsible for participant recruitment, clinical evaluation and autopsy coordination. The Clinical Core will recruit 300 older adults over the first two years and conduct annual clinical and cognitive assessments. Clinical assessments include annual neuropsychological testing, medical history and neurological examination, and assessments of function, behavior and mood, all of which will be used in the adjudication of cognitive diagnostic classifications in support of Projects 1, 2, 3 and 4. Cognitive diagnoses are adjudicated at biweekly diagnostic case conferences by a multi-disciplinary team from the Clinical Core. The Clinical Core also conducts assessments of vascular risk (arterial stiffness, carotid artery ultrasonography, and vascular endothelial function measures) and sleep (sleep diary, actigraphy, and polysomnography) at baseline, and 24- and 48-months, in support of Projects 1 and 2. The Clinical Core works with the Imaging Biomarker and Methodology Core and the Fluid Biomarker and Methodology Core, providing participants and coordinating scheduling and logistics for imaging and biofluid biomarker data to be obtained by these respective Cores. The Clinical Core transfers all clinical, cognitive, behavioral, vascular and sleep data to the Biostatistics and Data Management Core, and assists in merging these data with the imaging and fluid biomarker data. Finally, building on prior experience in coordinating autopsy cases, the Clinical Core confirms provisional autopsy intent and coordinates the logistics for any new autopsy cases in support of Project 4.