The purpose of this study is to evaluate and compare the changes of cognitive function (as measured by ADAS-Cog) in the two group of patients with Alzheimer's disease (AD) associated with and without white matter changes after rivastigmine patch therapy.

Acetylcholinesterase inhibitors (AChEIs) increase the amount acetylcholine at ACh receptors within the brain, and are the primary medications used to treat AD. Alzheimer's disease patients are frequently associated with mild or moderate white matter changes on MR imaging. The impact of whiter matter changes on the efficacy of cognition, functional abilities, behavioral and psychiatric symptoms and caregiver burden for probable Alzheimer's disease is not well known. There are very few studies for the efficacy of rivastigmine between the patients with mild to moderate Alzheimer's disease associated with or without vascular risk factors.

Recently, the rivastigmine patch demonstrated efficacy comparable to the highest doses of rivastigmine capsules, with markedly improved tolerability profile. The investigators hypothesized that rivastigmine patch will provide benefits to AD patients with white matter changes compared to those without any white matter changes. Possible explanation about favorable benefits for AD with white matter changes is that rivastigmine may act on both Alzheimer's and vascular pathologies contributing to dementia, providing additive treatment effects in patients suffering from both conditions concurrently. To our Knowledge, there was no study or clinical trial to compare the changes of cognitive function, ADL, BPSD and caregiver burden in two groups of patient with Alzheimer's disease associated with or without white matter changes after rivastigmine transdermal patch therapy.

Inclusion Criteria:

• AD in NINCDS-ADRDA criteria, mild to moderate
• probable AD with or without mild to moderate whiter matter lesions, excluding multiple large vessel infarcts or a single, strategically placed infarct (angular gyrus, thalamus, basal forebrain, territory of the posterior or anterior cerebral artery) on MRI scan (within 12 months)
• MMSE score : 10 to 26 at screening
• Hachinski scores ≤ 4
• No clinically significant laboratory abnormalities, such as thyroid disease, vitamine B12 deficiency or folic acid deficiency

Exclusion Criteria:

• Current evidence of history of neurological, psychiatric and other illness that could contribute to dementia
• Subjects with clinical significant cardiovascular disease, stroke, pulmonary disease or any other medical disease in the past 6 months
• History of cancer within the last 5 years
• Subjects with evidence or history of clinically significant allergic reaction to AchEI or drugs
• Subjects who had significant visual or hearing difficulties