Picture a world where a doctor prescribes a drug based on the results from a blood sample drawn. Alzheimer's disease (AD) is heterogeneous and complex; the symptoms are likely to arise from a combination of defects, the relative contributions of which are unique to that individual. We propose to focus on the contribution of mitochondria, which have been shown to be defective in AD, and profile 50 individual well-documented AD cases via characterization of blood-derived lymphoblast cell lines. We believe that peripheral cells such as blood cells, will be useful as a "window on the brain" to predict patient response to candidate drugs, paving the way for the development of drugs for selected sub-groups of AD patients. The goal is to more accurately predict groups of patients and predict responders and non-responders. Once we have the established assays, we will test known drugs.