From Thursday's Globe and Mail
May 3, 2007
Women who used estrogen hormone therapy before the age of 65 were less likely to develop Alzheimer's disease than women who didn't take the hormone, according to data released yesterday.
A subset study of the Women's Health Initiative, presented at the American Academy of Neurology's annual meeting in Boston, showed that women who used estrogen after the age of 65 had about a 50-per-cent increased risk of developing dementia. Those in that age group using estrogen and progesterone were at even greater risk.
The research adds yet another twist to the controversy over how and when to use hormone therapy for postmenopausal women. Here's a closer look at the latest results from the Women's Health Initiative - a landmark research project funded by the U.S. National Institutes of Health - and what these results mean for women.
Why is this research important? The Answer
The dementia study adds to a growing body of research that suggests that the timing of hormone therapy is crucial. In 2002, researchers halted part of the Women's Health Initiative because it appeared that women taking estrogen and progesterone for the study faced higher cardiovascular and breast cancer risks. As a result, thousands of postmenopausal women stopped using hormones.
But the women in that part of the study, with an average age of 63, were older than most women going into menopause. Now, investigators are beginning to look at the role of hormones in women younger than 63 - and are asking if the risk is the same. Last month, researchers said women in the study who used hormones in the years right after menopause - typically 45 to 55 years old - did not have elevated heart risks.
What about the hormones' effect on women's cancer risk?
According to the Society of Obstetricians and Gynecologists of Canada, there is a slightly increased risk of breast cancer among hormone users.
The effect after five years of combined estrogen/progestin hormone therapy is similar in magnitude to that of many other lifestyle variables: fewer pregnancies, delaying child-bearing until after the age of 30, less total time breastfeeding and more postmenopausal obesity.
Cigarette smoking, excessive alcohol use and lack of regular exercise also increase breast cancer risk.
Why does the age at which women take hormones make such a dramatic difference to their likelihood of developing Alzheimer's?
Some researchers have suggested that the "window of opportunity" hypothesis could explain why timing is crucial for women considering hormone therapy.
In this theory, the early use of estrogen - before there are pre-Alzheimer's changes in the brain - protects the healthy brain. But in older women, where changes have already begun to occur, the use of estrogen accelerates the process.
Will this study change how you prescribe hormone therapy?
This study suggests we can prescribe hormones with greater confidence to women in the early menopausal years. As always, each decision must be taken on a case-by-case basis. I continue to prescribe low-dose hormone therapy, for the shortest time possible, to those women with intractable hot flashes and night sweats. I do not recommend that patients take them indefinitely. For many younger menopausal women, the benefit of this therapy outweighs the risk.