Alzheimer's disease is the most common form of dementia and is the fourth leading cause of death among people 65 years of age and older. The global prevalence of the disease will increase significantly as the population ages, unless preventative treatments can be identified and marketed. The present study seeks to evaluate AZD3480 (TC-1734) compared to an approved medication (donepezil) shown to improve cognition and function in patients with Alzheimer's disease.