(HealthScoutNews) -- The National Institute on Aging is launching the first major study of the possible prevention of Alzheimer's disease.

"This is a landmark study because it's the first to look at preventing or delaying Alzheimer's disease in otherwise healthy individuals," says Dr. Edward Zamrini.

Zamrini is an assistant professor of neurology and director of the information transfer core of the Alzheimer's Disease Research Center at the University of Alabama, one of about two dozen sites participating in the trial.

Alzheimer's, a devastating brain disease that results in a progressive loss of memory and other cognitive functions, afflicts more than 4 million Americans. No one knows what causes it, and there's no cure or treatment.

The Alzheimer's Disease Prevention Trial will follow 900 post-menopausal women over the age of 65 to see if the hormone estrogen has any protective effect against the disease. Post-menopausal women face a higher risk of developing Alzheimer's.

Several studies have suggested estrogen may guard against loss of memory, and possibly Alzheimer's. One study, published in the journal Neurology in 1998, found women who used estrogen replacement therapy scored much higher on cognitive tests than women who didn't use estrogen.

Another study, this one published in The Lancet in 1996, found women who had taken estrogen developed Alzheimer's later than women who did not. The risk of developing the disease was also lower.

A third study also found a reduced risk for developing Alzheimer's in women who had used estrogen.

Though the exact biological mechanisms are unknown, scientists believe estrogen has a beneficial effect on nerve cells, particularly nerve cells in the hippocampus section of the brain. The hippocampus is critical for memory and learning functions, and tends to be affected early on by the disease. As Alzheimer's progresses, abnormal structures called plaques and tangles develop in the brain, and impede the function of nerve cells.

The Alzheimer's Disease Prevention Trial will look for any changes in memory in women who are taking estrogen versus those who are not. Age-related memory loss is still a very vague area of research, but there's a suspicion it could be a precursor to Alzheimer's.

"It's not at all clear who among people who have age-related memory loss is going to go on to have more serious loss," Zamrini says. "But there is a growing concern in the scientific community that this is an indicator that [these people] are likely to continue to further deteriorate and probably ultimately develop Alzheimer's."

About 10 percent of people over the age of 65 have Alzheimer's; almost half of those over 85 have the disease.

The University of Alabama will enroll 50 women in its portion of the study. Women who are 65 and older are eligible if they have a family history of Alzheimer's but don't have any significant memory loss themselves. Women who have taken estrogen or hormone replacement therapy in the past year or who have a history of breast, uterine or ovarian cancer are not eligible.

The women will be split into two groups -- one receiving estrogen and the other receiving a placebo -- and followed for five years.

"This will allow us to see what is the rate of development of memory changes," Zamrini says. "That will allow us to tell if, indeed, taking estrogen before one has Alzheimer's has a protective effect."

Men aren't included in the study because they essentially produce their own estrogen for most of their life, whereas women cannot.

What To Do

Here's more information, including how to become a volunteer, on the Alzheimer's Disease Prevention Trial.

For more information on Alzheimer's and estrogen, visit the Alzheimer's Association or the Alzheimer's Disease Education and Referral Center.

Reference Source 101

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