TUESDAY, Nov. 5, 2002 (HealthDayNews) -- Older women who formerly used hormone therapy for 10 years or more are less likely to get Alzheimer's disease than those who never took hormones.
That's the conclusion of a new study that appears in tomorrow's Journal of the American Medical Association.
The researchers caution, however, that until scientists learn more about the health risks and benefits of hormone replacement therapy (HRT), their study should not be viewed as an endorsement of the treatments.
The study followed approximately 3,200 men and women in Cache County, Utah, for five years, beginning when they were 73 or 74 years old. Women who used HRT had a 41 percent reduction in their risk of Alzheimer's, compared to those who never received the therapy. Those women who used it for more than 10 years had a 2.5-fold lower incidence of the disease, compared with non-users.
Nearly all of the risk reduction was associated with former use of HRT, not current use, unless the women had used it for more than 10 years, the researchers found.
As good as that might sound to a woman fearful of getting the degenerative brain condition marked by severe memory loss, the study results are not, by themselves, a reason to sign on for long-term hormone therapy, says Dr. John C.S. Breitner.
"I wouldn't tell [a woman] to take HRT based on these data," says Breitner, a study co-author and head of geriatric psychiatry at the University of Washington.
"If you have other good reasons to take it, you might get some additional reassurance from these findings," he adds.
About 4 million Americans have Alzheimer's disease, according to the Alzheimer's Association.
In the past several months, women on HRT or those contemplating its use have been bombarded with a spate of studies about its pros and cons. In July, the estrogen-progestin arm of the Women's Health Initiative study was halted after researchers found a small but significant increase in the risk of heart disease, breast cancer and other problems after 5.2 years of use. The estrogen-only arm of the study is continuing.
In the latest study, the researchers concluded that HRT use is associated with a reduced risk of Alzheimer's disease later in life. During the follow-up period, 2.6 percent of the men and 4.7 percent of the women developed Alzheimer's. Researchers have known that women appear to be at increased risk of Alzheimer's after age 80 or so, compared to men.
When they looked more closely, the researchers found no apparent benefit for current users, but rather for former users who had used HRT for more than 10 years. Those who had used it previously for 10 years or more reduced their risk so it was now comparable to the men's risk of getting Alzheimer's, the researchers say.
The researchers suspect there may be a window of opportunity, around menopause, when the depletion of a woman's level of estrogen may have the greatest harmful effects on the brain's neurons. Hormone therapy is thought to make the neurons more active, help them grow and perhaps ward off toxic substances that can set you up for Alzheimer's, Breitner explains.
However, the researchers can't say for sure that it's the hormones that help ward off the disease. Women who decided to take hormone therapy, at least before the halting of the estrogen-progestin portion of the Women's Health Initiative, may simply be more health-conscious, Breitner says, echoing the caveats of other researchers.
Another Alzheimer's expert, Susan M. Resnick, an investigator at the National Institute on Aging's Laboratory of Personality and Cognition, says the new study, while interesting, has limitations. They include the overall health habits of some of the women in the study that could have contributed to their reduced risk of Alzheimer's, says Resnick, who wrote an editorial to accompany the study.
Like Breitner, Resnick says she would not recommend any treatment options based on the new study. Several other studies under way will help provide answers about HRT and Alzheimer's disease in coming years, she says. One such study is the Women's Health Initiative Memory Study, or WHIMS, the segment of the study that will look at the link between HRT and Alzheimer's disease.
Resnick acknowledges that waiting on the results of these and other studies can be frustrating for women faced with a decision about HRT now. However, she says, "We are going to have to realize that the risk-benefit profile [of hormone replacement therapy] may change as we consider other outcomes."
What To Do
For more information on Alzheimer's disease, see the Alzheimer's Association or the National Institute on Aging.
