Genetic Risk for Alzheimer's in Early Menopausal Women Lead Investigator: Tamar Rodney Institution : Johns Hopkins University E-Mail : trodney1@jhu.edu Proposal ID : 1439 Proposal Description: Aims Aim 1: To compare the risk of Alzheimer?s Disease and onset for early (before 45 years old) vs late estrogen replacement therapy users (>51 years old) for female APOE carriers. Hypotheses - Aim 1: Late Estrogen Replacement female APOE carriers will have an increased risk and earlier onset of Alzheimer?s disease occurrence compared to Early Estrogen Replacement Therapy.#8239 Aim 2:#8239To compare Alzheimer?s disease frequency APOE genotypes to determine if certain allele combinations (E2/E3/E4) are associated with Alzheimer disease for early ERT users (before 45 years old) and late ERT users (>51 years old). Hypotheses-#8239Aim 2: Combinations of genotypes containing E4 allele will have a higher frequency of Alzheimer?s occurrence than other genotypes with other alleles for Early and Late ERT. Methods: Analysis for Aim 1: To compare risk for developing Alzheimer?s disease occurrence for female APOE carriers who had early vs late estrogen replacement therapy. Correlation of Age and development of AD One Way ANOVA: To compare age of onset between early and late ERT-Compare mean of age of onset of Alzheimer?s disease for early and late ERT Control for any relevant variables. Analysis for Aim 2: To frequency analysis: Stratify for Early ERT and Late ERT. Compare means for both using ANOVA ? compare frequencies of Alzheimer?s disease for different allele combinations. Utilize an Analysis of Covariance ( ANCOVA) model if appropriate with identified covariates (control for different allele combination) Type of Data Needed: Date from female APOE carriers of APOE genotype, occurrence of Alzheimer?s disease, age of Alzheimer's onset, age of earliest recorded ERT treatment.#8239Any demographic data related to the sample would be also helpful.