 This is a randomized study drug assigned by chance, double-blind neither the physician nor the patient know the name of the study medication, placebo-controlled, parallel-group study to evaluate the efficacy and safety of two fixed doses of galantamine 16 and 24 milligrams per day mgday in patients with Alzheimers disease. The study consists of a 4-week screening period during which all patients will receive placebo, and a 24-week double-blind treatment period during which patients will receive placebo, galantamine 16 mgday, or galantamine 24 mgday. For patients receiving galantamine treatment, the starting dose is 8 mgday and increases at 4-week intervals in increments of 8 mgday. The primary measures of effectiveness are the change from baseline to the end of the study week 24 in the Alzheimers Disease Assessment Scale - Japan cognitive subscale ADAS-J cog and the Clinicians Interview-Based Impression of Change plus - Japan CIBIC plus-J. Safety assessments include the incidence of adverse events, clinical laboratory tests, vital signs, electrocardiograms ECGs, and physical examination findings. The study hypothesis is that galantamine will be effective in the treatment of Alzheimers disease. Study drug taken orally twice a day. 