Cognitive Changes in Alzheimer's Disease Patients Associated With or Without White Matter Changes After Rivastigmine

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