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Alzheimer's Disease Health Center

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Causes of Alzheimer's Disease

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Researchers don't know exactly what causes Alzheimer's disease. There are probably a lot of things that are behind it. But as scientists have learned more about the condition, they’ve found clues about where symptoms come from and who’s at risk.

The Brain and Alzheimer's Disease

When a person has Alzheimer’s, his brain changes. It has fewer healthy cells, and it gets smaller over time. Most of the time, the brain cells also form two types of flaws:  

  • Neurofibrillary tangles. These are twisted fibers inside brain cells that keep nutrients and other important things from moving from one part of the cell to another
  • Beta-amyloid plaques. These are sticky clumps of proteins that build up between nerve cells instead of breaking down like they do in healthy brains.

Plaques and tangles damage the healthy brain cells around them. The damaged cells die, and the brain shrinks. These changes cause the symptoms of Alzheimer’s, such as memory loss, speech problems, confusion, and mood swings.

Brain cells affected by the disease also make lower amounts of the chemicals called neurotransmitters that nerves use to send messages to each other.

Scientists don't know if these brain cell changes cause Alzheimer’s or happen because of it.

What Can Lead to Alzheimer's Disease?

There are a few things that may make people more likely to get Alzheimer’s. So far, research has linked the disease with:

  • Age. Your risk for Alzheimer's goes up as you get older. For most people, it starts going up after age 65.
  • Gender. Women get the disease more often than men.
  • Family history. People who have a parent or sibling with Alzheimer’s are more likely to get it themselves.
  • Down syndrome. It’s not clear why, but people with this disorder often get Alzheimer's disease in their 30s and 40s.
  • Head injury. Some studies have shown a link between Alzheimer's disease and a major head injury.
  • Other factors. High cholesterol levels and high blood pressure  may also raise your risk.


WebMD Medical Reference

Reviewed by Neil Lava, MD on June 28, 2014
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