Alzheimer's disease is a progressive condition that destroys the connections between cells in the brain. Eventually these cells die, which affects how the brain works. As cells die in the outer layer of the brain—called the cortex—it shrinks, and the spaces in the brain get larger. The cortex includes the hippocampus, which is an area of the brain that helps new memories form.

The damage to the brain eventually causes problems with memory, intelligence, judgment, language, and behavior.

Alzheimer's is the most common form of mental decline, or dementia, in older adults.