MRIs Show Slightly More Brain Decay in Women on Estrogen
May 5, 2000 -- A study's finding that elderly women who take estrogen have brains that are slightly more decayed than those of other women their age worries Teri Manolio, MD. She's worried not because of the finding -- she calls it a "very, very small difference" -- but because women who hear about it might stop taking their hormone replacement therapy.
Manolio, director of the epidemiology and biometry program at the National Heart, Lung, and Blood Institute (NHBLI), was part of a team that looked at sophisticated brain studies from 2,133 women with an average age of 75 years. Overall, the women who took estrogen scored better on tests of mental function. But magnetic resonance imaging (MRI) scans showed that specific areas of their brains had decayed more than those of women who didn't take estrogen. In some women, the more decay, or atrophy, there was, the worse they did on the mental-function tests.
In a paper published Friday in a medical journal, Manolio and co-workers note that the brain changes they detected have been linked to mental decline. Manolio tells WebMD that this means only that future researchers should keep this in mind -- not that patients should take action. "Our interpretation is that these are very small changes that don't make a clinical difference," she says. "They are probably more related to why people are taking the hormone than to the hormone itself."
Barbara B. Sherwin, PhD, co-director of the McGill University Menopause Clinic, was the first researcher to show that estrogen protects memory and improves new learning in menopausal women. "That was 15 years ago, and since then we have been doing a lot of studies to see if those findings hold up," she says. "It certainly has held up across time."
Sherwin, who was not involved in the NLHBI study, says that the authors focused too much on the difficult-to-read MRIs. "How do you account for the fact that [mental] functioning improved in estrogen users?" she asks. "They are putting all their money on [MRI] studies, rather than the fact that women who take estrogen are actually performing better as a group -- which seems to me to be the crucial thing. If they are finding small differences in their brains, it's hard to say what that means."
The current study clearly does little to resolve the ongoing scientific and medical controversy over estrogen replacement therapy. Why all the fuss? "It is a very complicated issue," Sherwin says. "Estrogen has effects on bone mass, on the heart, on the brain, and long-term use is associated with breast cancer. Like any other drug, there is a risk/benefit issue for women. Some people focus on the positives, some on the negatives -- it's a mixed bag of things."
An ongoing study should provide answers to many of these questions. Funded by the U.S. National Institutes of Health, the Women's Health Initiative Memory Study hopes to enroll a very large number of women 65 and older. For six years, these women will take either estrogen or a pill that looks like estrogen but does nothing. But the first results from the study won't be available until 2005.
Meanwhile, Manolio has a message for women who may be frightened by the finding of estrogen-related brain decay. "Basically, this is a very secondary issue in terms of decisions to take or not to take estrogen," she says. "Women need to take their physicians' advice -- this is nothing on which to change their behavior."