The finding, reported today in the journal Neurology, is the latest in a series of reports suggesting that estrogen replacement therapy has a broad range of dramatically beneficial effects. Several studies have shown that estrogen replacement therapy not only increases bone density and lowers cholesterol levels, but also decreases the risk of colon cancer, improves skin tone and even extends life span.

Although experts agreed that most post-menopausal women probably should be taking estrogen because there are so many beneficial effects, "there really are downsides to estrogen for a small population," cautioned Dr. Claudia Kawas of the Johns Hopkins Bayview Medical Center in Baltimore, one of the co-leaders of the study. The decision to take the drug, she said, "really has to be between a woman and her doctor."

Today's estrogen results highlight estrogen's emergence as the newest weapon in the growing arsenal of drugs that may delay or prevent Alzheimer's. The findings follow on the heels of two other recent studies that found significant protective effects against Alzheimer's from Vitamin E, the anti-Parkinson's drug selegiline and the anti-inflammatory drug ibuprofen. Researchers are hurriedly designing clinical trials that will determine the benefits when two or three are taken together.