Screening For Alzheimers

The following article was provided by www.Mayoclinic.com

Most scientists agree that a screening test for Alzheimer's - one that will predict with certainty those who will develop the disease - is still years away. However, genetic research offers some important clues about Alzheimer's that may eventually lead to the development of a screening test.

Discovering Clues
Some of the most exciting clues about Alzheimer's come from the following three areas of genetic research:

• Gene defects—Up to 40% of cases of early-onset (before age 65) Alzheimer's are hereditary. Since the 1990s, researchers have made progress in understanding the mutations or defects in three genes—presenilin 1 and 2 and the amyloid gene—implicated in early-onset, hereditary Alzheimer's. Researchers are now close to identifying a gene or chromosome that may be important in late-onset dementia.
   
• Plaque formation - Plaques (found in the brains of people with Alzheimer's) are mainly composed of a protein called beta-amyloid, a by-product of a larger protein involved in cell membrane function. Cells throughout the body secrete beta-amyloid protein, but the brain produces particularly large amounts. Beta-amyloid plaques develop in the spaces between nerve cells early in the disease process - before any evidence of surrounding nerve cell damage and 10 to 20 years before symptoms develop. Mayo Clinic researchers participated in a study that confirmed that a specific form of this protein is not a result of the disease but rather is critical to the development of the disease. Researchers want to understand the normal function of beta-amyloid protein, how and why it accumulates and what role it plays in the death of nerve cells. Understanding this process may lead to treatments that interrupt the fundamental processes that lead to Alzheimer's.
   
• Role of tangles and tau - The internal support structure for nerve cells depends on the normal functioning of a protein called tau. In people with Alzheimer's, threads of tau protein undergo changes that cause them to become twisted and tangled. Many researchers believe this seriously damages the nerve cells, causing them to die. However, scientists don't know if the development of tangles is an attempt on the part of the cells to strengthen the support structure or to damage and ultimately destroy nerve cells. Understanding this sequence of events may lead to treatments that intervene at critical points in the development of the disease.

Closer to a Test
Laboratory tests can measure levels of amyloid proteins and tau proteins. But no definitive test predicts who will develop Alzheimer's. As scientists uncover more information about Alzheimer's, they may eventually develop a test - perhaps within the next decade - that can predict this devastating disease.

For more information, visit the Alzheimer's Center at MayoClinic.com.

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