The University of Washington Alzheimer's Disease Patient Registry (ADPR) is a model clinical and epidemiologic database for dementia and dementia of the Alzheimer's type (DAT). It was established in late 1986 by a grant from the National Institute on Aging and is based in a large health maintenance organization -- Group Health Cooperative of Puget Sound (GHC). The ADPR enrolls only those cases of dementia and DAT who have come to medical attention since 1 January 1987; providing each of the potential cases with a standardized, physical, neurological and neuropsychological examination leading to a criteria-based diagnosis. The goal of this application is to continue the model ADPR for another three years so that additional cases can be enrolled; additional cases will allow ongoing epidemiologic/genetic studies to proceed and make future investigations feasible. The specific aims of the project are: 1. To identify GHC patients who come to medical attention for (previously undiagnosed) dementia and to provide each of these patients with a standardized, thorough examination for dementia and to assign based on established criteria; 2. To enroll the identified patients in the ADPR and to maintain a detailed database including epidemiologic, clinical and family history data; this database will provide cases for other investigations especially concerning diagnosis, etiology and risk factors for DAT and other dementias; 3. To describe the course of dementia, in particular DAT, in terms of cognitive and functional decline, survival and clinical- pathologic correlations. 4. To compare the annual case identification rate of dementia and DAT from the GHC population base with published estimates of incidence.