Alzheimer's disease (AD) is the most common dementia, accounting for 60-80% of cases in the elderly. It afflicts 5-10%of the population over the age of 65, and as much as 45% of the population over 85. The earliest sign is typically animpairment of recent memory function and attention, followed by failure of language skills, visual-spatial orientation,abstract thinking, and judgment. Inevitably, alterations of personality accompany these defects.