Independent Perspective News

CHICAGO, Illinois (Reuters) -- Post-menopausal hormone replacement therapy may help prevent Alzheimer's disease when the drugs are used for 10 years or more, a study said on Tuesday.

The study, published in this week's Journal of the American Medical Association, will add to the fierce debate over hormone replacement therapy, which recent research has shown is not as safe and helpful as was previously believed.

"Our findings, along with other recent work, suggest that (such therapy) may be effective for the primary prevention of Alzheimer's disease, if not for its treatment," the Veteran's Administration, which had a team working on the study, said in a statement.

Hormone replacement therapy using a combination of estrogen and progestin was popular among millions of women seeking to ease the symptoms of menopause including hot flashes and mood swings. It had also been promoted to lower the risk of heart disease, to keep women feeling younger and to prevent bones from becoming brittle.

But a study published in July cast doubt on the treatment, saying it increased the risk of heart disease and breast cancer when used for more than five years. The government strengthened the warning labels on the drugs used in that study -- Wyeth's PremPro and Premarin.

In the study released on Tuesday, Peter Zandi of Johns Hopkins University in Baltimore and colleagues looked at the rates of Alzheimer's disease between 1995 and 2000 in 1,889 women, all elderly, in Utah. Women who had used HRT drugs for at least a decade were 2.5 times less likely than women who had never used them to develop Alzheimer's.

The study, funded by the National Institutes of Health, included teams at the Veteran's Administration, Puget Sound Health Care System in Washington, Duke University in North Carolina, the University of Washington and Banner Health System in Phoenix, Arizona.

Calcium supplements, rats and dementia

The study also looked at the use of calcium supplements and multivitamins and found women who used them did not have a lower risk of Alzheimer's "A new finding in this study is an apparent limited window of time during which sustained (replacement therapy) exposure seems to reduce the risk of Alzheimer's disease," the VA said.

"We found that, in contrast with (use earlier in life) ... exposures within 10 years of Alzheimer's onset yielded little, if any, apparent benefit," they added, theorizing that estrogen may protect against Alzheimer's only before extensive damage had occurred in the brain.

"The current data are insufficient to recommend hormone therapy for prevention of Alzheimer's disease," Susan Resnick of the National Institute on Aging in Baltimore and Victor Henderson of the University of Arkansas for Medical Sciences in Little Rock, Arkansas, said in a commentary.

"The results ... indicate that former users of hormone therapy have a greater reduction in the incidence of Alzheimer's disease than current users. Among current users, only long-time users (greater than 10 years) appeared to benefit," they added.

A study in rats published separately on Tuesday could shed light on this. A team at the University of Pittsburgh removed the ovaries of lab rats, effectively causing menopause, and then gave some estrogen. The rats that got estrogen did better in a maze than rats not given the hormone, they reported in the November issue of Hormones and Behavior.

Some of the rats had certain neurons, or brain cells, removed and those rats were not helped by the estrogen.

"The study ... suggests why starting estrogen after dementia has developed is ineffective. For estrogen to work, the neurons must be alive and working," Dr. Sarah Berga, a professor of obstetrics, gynecology and reproductive sciences at the university who did not work on the study, said in a statement.