HRT Now Linked to Alzheimer's, Dementia

May 27, 2003 -- Hormone replacement therapy is under scrutiny again.

Last summer, a landmark study linked hormone replacement therapy (HRT) to heart disease, stroke, and breast cancer. And now, there's more news about HRT -- none of it good. This time, it's about dementia and Alzheimer's disease.

"Many women were willing to risk the possibility of a slight increase in adverse events if hormone therapy could prevent dementia, especially Alzheimer's disease," writes Kristin Yaffe, MD, in an editorial accompanying the study in the May 28 issue of The Journal of the American Medical Association.

Indeed, once thought to protect a woman from dementia and Alzheimer's disease, combined HRT -- estrogen-plus-progestin -- now seems to cause thinking and memory impairment.

The three new studies -- all involving women enrolled in the Women's Health Initiative -- look at HRT's effects on disorders affecting the brain, such as stroke, dementia, and milder forms of impaired thinking.

In fact, the addition of progestin to the HRT formula may create the detrimental effect, Yaffe writes. Progestin has been shown to modify the beneficial effects of estrogen -- possibly increasing the risk of heart disease and dementia, she states.

Researchers are only beginning to really understand the biological effects of estrogen replacement, writes Yaffe. A woman's age when she begins taking HRT, how long she takes it, and if she gets it from a patch or a pill -- all could have an effect on her risk.

"Until these questions are answered ... hormone therapy should be prescribed only for temporary use to treat menopausal symptoms," Yaffe writes.

For women trying to sort through the data, to make their own decisions, here's a summary of today's findings and advice from experts.

HRT, Dementia, and Mild Thinking Impairment

The first study looks at more than 4,500 women, all over age 65, with no memory or thinking problems at the study's onset. Half the women took HRT in pill form; the other women got a placebo pill.

Five years later, researchers found 61 cases of dementia; the majority -- 66% -- were in the HRT group, reports Sally A. Shumaker, PhD, epidemiologist with the department of public health sciences at Wake Forest University in Winston-Salem, N.C.

In fact, HRT doubled the likelihood of dementia, and the effects were evident early on -- just one year after the women began taking HRT.

Also, HRT did nothing to prevent mild thinking impairment in these women, writes Shumaker.

It's important to keep her findings in perspective, writes Shumaker. Her study looked at women over age 65, not at younger women. Also, the number of women who developed dementia was relatively small, even though the numbers were noteworthy, she writes.

No Protective Effects

Another study looked at whether HRT could help preserve memory and thinking -- or at least slow its decline associated with aging. No such luck.