What Is Alzheimer's Disease?
Dementia is a brain disorder that seriously affects a person's ability to carry out daily activities. Alzheimer's disease -- the most common form of dementia among older people -- initially involves the parts of the brain that control a person's thought process, memory, and language.
Alzheimer's disease bears the name of Dr. Alois Alzheimer, a German physician. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental disorder. During the autopsy, he found abnormal clumps (now called amyloid
plaques) and tangled bundles of fibers (now called neurofibrillary tangles) within the brain. Today, these plaques and tangles are considered classic signs of Alzheimer's disease.
Scientists have also found other brain changes in people with Alzheimer's disease, including:
- The death of nerve cells in areas of the brain that are vital to memory and other mental abilities
- Disruptions in the connections between nerve cells
- Lower levels of some of the chemicals in the brain that carry messages back and forth between nerve cells.
All three of these changes may contribute to the impaired thinking and memory seen with Alzheimer's disease.
Age is the most important risk factor for Alzheimer's disease.
In fact, the number of people with this disease doubles every 5 years after age 65.
Alzheimer's research scientists are studying the role of genetics in the development of Alzheimer's disease. Researchers have discovered three genes that cause early symptoms of (familial) Alzheimer's disease and other genetic mutations that cause excessive accumulations of amyloid protein. The buildup of these proteins is associated with age-related (sporadic) Alzheimer's disease.
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