A 24 Week, Multicenter, Randomized, Double-Blind, Placebo-Controlled Evaluation of the Safety and Efficacy of Donepezil Hydrochloride (E2020) in Patients With Severe Alzheimer's Disease Followed by a 12 Week Open-Label Extension Period

Donepezil hydrochloride (Aricept) has been approved to treat symptoms associated with mild to moderate Alzheimer's disease (AD). Aricept has been shown to improve the memory and thinking abilities, activities of daily living and global function in patients. The purpose of the study is to further investigate the effectiveness and safety of donepezil in patients with severe Alzheimer's disease. Donepezil is thought to work in the brain by increasing the levels of an important brain chemical called acetylcholine. This chemical helps a person's memory to work better.