LY450139: Tolerability and Biomarker Assessment in Subjects With Mild to Moderate Alzheimer's Disease

The purposes of this study are to determine: - The safety of LY450139 dihydrate and any side effects that might be associated with it. - How much LY450139 dihydrate should be given and how long it may be detected in blood. - To determine if LY450139 dihydrate may have an effect on a protein found in blood, called A beta. This protein is studied in subjects with Alzheimer's disease. - To collect and store samples from blood and spinal fluid for research related to Alzheimer's disease and similar (neurodegenerative) diseases or inflammation (irritation) that may provide information on how subjects respond to LY450139 or other medications. Length of study: Approximately 29 weeks. Number of office visits: 11 for most subjects: initial visit, every other week during 14 weeks of study drug treatment, and 2 follow-up visits. At no cost, approximately 45 eligible participants will receive: - Study medication - Study-related diagnostic and laboratory evaluations