The Central Coordinating Core (CCC) is responsible for clinical recruitment and follow-up, database management, administration, and strategic planning across the PPG. The CC implements the overall longitudinal design of the PPG. The goal is to recruit and to follow a sample of 500 subjects: 250 normal controls and 250 subjects with variable degrees of cognitive impairment attributed to subcortical ischemic vascular dementia (SIVD) or Alzheimer disease (AD). For normal controls, cognitive/functional status is assessed every 2 years and magnetic resonance imaging (MRI) is repeated every 4 years. For subjects, cognitive/functional status is followed every year, and MRI is repeated every 2 years and magnetic resonance imaging (MRI) is repeated every 4 years. For subjects, depend upon the CCC for classifying subjects and for ensuring the quality of key cognitive/functional data. Although the Pathology Core ultimately determines the likelihood of SIVD, AD, or mixed AD/SIVD, the CCC is responsible for obtaining consent and for coordinating the autopsy program. The CCC manages data from all three Cores (Clinical, Imaging, and Pathology). Key clinical variables include demographics, onset and duration of dementia, activities of daily living, mental status scores, neuropsychological test cores, clinical dementia rating (CDR), clinical diagnosis, and subject categorization. Key imaging data include the number, location, and size of lacunes, the volume of cortical gray matter, white matter; white matter hyperintensities (WML), ventricular and sulcal cerebral spinal fluid, and the volume of the hippocampi. The key pathological data include Braak and & Braak Staging, CERAD rating of neuritic plaques, and severity and distribution of ischemic brain injury and cerebrovascular disease. These data are utilized by all four of the research projects. PPG investigators work well together. In person meetings are held at least twice a year to review progress, set goals, ane to plan strategy. Monthly teleconferences and e-mail mitigate the geographic distances between campuses. Consultants and an external advisory group provides invaluable feedback and guidance. The PPG functions as a vital and cohesive whole.