Mechanics of Alzheimer's Disease

Alzheimer's disease is a form of dementia characterized by the degeneration of healthy tissue inside the brain. The mechanics, or mechanisms, of the disease follow certain general patterns of development.

The Facts

• The National Institute on Aging (NIA) reports that researchers do not know precisely why Alzheimer's begins in a given individual. It is known, however, that the brain changes that eventually trigger Alzheimer's may begin as long as 10 to 20 years before symptoms manifest.

Plaques and Tangles

• The Mayo Clinic and the Alzheimer's Association note that two abnormal structures---known as plaques and tangles---typically appear in the brains of individuals with Alzheimer's. Plaques form from clumps of a protein called beta-amyloid, while tangles form from alterations in a protein called tau, which normally helps support brain cells.

Brain Cell Death

• The buildup of plaques and tangles degrades the function and communication abilities of brain cells, notes the NIA. Eventually, brain cells begin to die.

Progressive Damage

• In time, brain cell death extends to an area of the brain called the hippocampus, reports the NIA. The hippocampus plays a vital role in the brain's ability to form memories.

Advanced Effects

• Advancing brain cell death triggers shrinking in affected areas of the brain. Eventually, this process causes widespread brain damage, notes the NIA.