ALADDIN is a clinical trial investigating the safety and effectiveness of leuprolide (a hormone drug) to improve the cognitive function and slow the progression of Alzheimer's disease (AD). The study will include treatment of men 65 years and older with mild to moderate Alzheimer's disease who reside in the community. The objective is to evaluate the safety and efficacy of two different doses of leuprolide to improve the cognitive function and slow the progression of AD, as measured by the ADAS-COG and the Clinical Global Impression (CGI). Measures of behavioral disturbances, and quality of life of the caregiver will be made also. The study design is randomized, double blind, placebo-controlled, parallel group design with a 2:1 randomization of drug to placebo. Sample size will include 90 participants from multiple test sites.