Alzheimer's disease (AD), one form of dementia, is a progressive, degenerative brain disease. It affects memory, thinking, and behavior.

Memory impairment is a necessary feature for the diagnosis of this or any type of dementia. Change in one of the following areas must also be present: language, decision-making ability, judgment, attention, and other areas of mental function and personality.

The rate of progression is different for each person. If AD develops rapidly, it is likely to continue to progress rapidly. If it has been slow to progress, it will likely continue on a slow course.

Senile dementia/Alzheimer's type (SDAT)