Alzheimer's disease is a medical illness that damages the brain and causes problems with memory, mood and behavior. A substance called acetylcholine (ACh), which is naturally produced in the body, plays an important role in the normal functioning of the brain. In subjects with Alzheimer's disease, the level of ACh is greatly reduced. Currently, there are three commonly prescribed drugs used for treating the symptoms of Alzheimer's disease by helping to maintain the level of ACh in the brain. This study will evaluate how much each of these drugs changes the levels of certain brain chemicals that are known to, or may play an important role in, Alzheimer's disease and its symptoms.

Ages Eligible for Study:  50 Years   -   85 Years,  Genders Eligible for Study:  Both

Criteria

Inclusion Criteria:

• Clinical diagnosis of mild to moderate Alzheimer's disease
• Must be able to swallow capsule/tablet
• Must have a caregiver who is available to attend all study visits

Exclusion Criteria:

• Digestive problems related to peptic ulcer
• Experienced a heart attack or stroke in the last 6 months
• Serious/unstable asthma or severe pulmonary (lung) disease
• On current treatment with a blood thinner