Hormone Therapy Linked to Brain Atrophy in Older Women

 

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By Anne Harding

MONDAY, Jan. 12, 2008 (Health.com) — Not too long ago, millions of postmenopausal women were taking estrogen as part of hormone therapy to protect their hearts, prevent cancer, and keep their brains sharp.

But two new studies in the journal Neurology show that not only does hormone replacement therapy increase the risk of heart attack, stroke, blood clots, and breast cancer in women over the age of 65, but it also shrinks their brains.

"This is extra-double-triple reason not to go on estrogen after 65," says Constantine Lyketsos, MD, of the Johns Hopkins Bayview Medical Center in East Baltimore, Md. Dr. Lyketsos, an expert on dementia treatment, was not involved in the research.

Experts say the findings should not be cause for alarm among younger women who are taking estrogen according to the current guidelines. The U.S. Food and Drug Administration recommends that women who take hormones to treat hot flashes and other menopausal symptoms start doing so as early as possible, at the lowest effective dose, for the shortest time possible. (Women who haven't had a hysterectomy need to take a combination of estrogen and progestin, because estrogen alone increases the risk of cancer of the lining of the uterus; women who've had their uterus removed can take estrogen alone.)

There is good evidence that for younger women, estrogen can actually help defog the brain, improve mental function, and possibly even protect against Alzheimer's disease decades later, says Pauline Maki, PhD, who runs a research program on steroid hormones' effect on cognitive function at the University of Illinois at Chicago. She was not involved with the new studies.

One of the most plausible explanations for this paradox is the "healthy cell bias of estrogen." In other words, estrogen is good for healthy cells, and bad for unhealthy cells, she explains. In her own research, Maki has shown that women who experience an unusually high number of hot flashes during menopause have worse verbal memory.

"What I think happens is that women's brains during hot flashes, while they're not sleeping as well, the brain material is still fine," Maki says. "When you introduce estrogen to these women, you're introducing it into a healthy cell, and the results cognitively are generally beneficial."

Older women's brain cells are likely to be in worse shape than younger women's, especially if their mental faculties are already fading. "The scenario that seems to arise is one where [hormone therapy] at the dose of this trial is harmful to the frailest brains, but perhaps not to the strongest ones," Giovanni Frisoni, of the National Center for Research and Care of Alzheimer's Disease in Brescia, Italy, says. Dr. Frisoni has studied estrogen's effects on brain volumes, but was not involved in the new research.