There are two abnormal structures in the brain associated with Alzheimer’s disease. Amyloid plaques (pronounced AM-i-loyd) are clumps of protein fragments that accumulate outside of cells. Neurofibrillary (pronounced NUR-o-FI-bri-lair-ee) tangles are clumps of altered proteins inside cells. Research about these structures have provided clues about why cells die, but scientists have not determined exactly what role plaques and tangles play in the disease process and whether these are the key factors.

The person with AD may experience confusion, personality and behavior changes, impaired judgment, and have difficulty finding words, finishing thoughts or following directions. It eventually leaves its victims incapable of caring for themselves. The disease usually begins gradually, causing a person to forget recent events or familiar tasks. The loss of brain cells eventually leads to the failure of other systems in the body. The rate of progression of Alzheimer's varies from person to person. The time from the onset of symptoms until death ranges from 2 to 20 years. The average duration is about 8 years.

Inside the Brain: An Interactive Tour
Learn what happens in the brain of a person with Alzheimer’s disease.
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