Scientists are racing to find a cure as millions of people reach the age when Alzheimer's is most commonly manifested (Plontz).

Experts are still trying to fully understand the cause or causes of Alzheimer's disease. In the meantime, it's helpful to understand the hallmarks of Alzheimer's -- plaques and tangles -- and the risk factors that affect a person's likelihood of developing the disease (Hill).

Alzheimer's disease is characterized by a build-up of proteins in the brain. Though this cannot be measured in a living person, extensive autopsy studies have revealed this phenomenon. The build-up manifests in two ways: Plaques -- deposits of the protein accumulate in the spaces between nerve cells. Tangles -- deposits of the protein that accumulate inside of nerve cells.

Scientists are still studying how plaques and tangles are related to Alzheimer's disease. One theory is that they block nerve cells' ability to communicate with each...
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