The purpose of this study is to determine the distribution of the Apolipoprotein E (APO-E) alleles in Alzheimer's disease (AD) patients and healthy elderly, the possible ethnic variations in the distribution of the APO-E alleles and to assess whether neuropathological and clinical variability and rate of decline in AD are accounted for by APO- E genotype. In addition we wish to establish a DNA bank for the testing of possible markers of AD. Since support was renewed in February 1996, collection of blood for the extraction of DNA from WBC's continued in all the live subjects participating in the Hopkins Alzheimer's Disease Research Center (ADRC). The remaining extracted DNA is stored for future studies. DNA from deceased subjects was extracted from frozen and fixed brain tissue. A total of 161 samples have been typed since funding was granted in June 1994. In the last funding period (12/l/95 through 11/30/96), a total of 23 participants have been genotyped. Of these 13 where women and 10 were men. Final results on prevalence of the Apo-E genotypes, racial differences and clinical and neuropathological correlations will be available in 1997 with completion of the typing of the entire cohort.