Functional Magnetic Resonance Imaging (fMRI) of Anosognosia in Amnestic Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD)

Inclusion Criteria: * Amnestic MCI: 1. Observation of memory decline by informant. 2. Mini Mental Status Exam (MMSE) score between 24 and 30. 3. Objective memory impairment on neuropsychological tests. 4. Intact functional abilities, and 4) no diagnosis of dementia. * AD: 1. A diagnosis of probable AD according with the NINDS-ADRDA and DSM-IV diagnostic criteria. 2. MMSE score between 16 and 27. All AD patients will have capacity to provide informed consent as judged by the referring physician. Exclusion Criteria: * MRI incompatibility; history of neurologic disease (including prior loss of consciousness of more than 10 minutes); prior neurosurgery; or chronic medical diseases (such as poorly controlled diabetes, renal disease, or poorly controlled hypertension). * Excluded medications include neuroleptics, short or long acting nitrates, and Warfarin. * Other exclusions include: less than 10 yrs of education; Hachinski scale of 4 or more; first language other than English; poor visual or auditory acuity; pregnancy.