The Associated Press

- An estrogen alternative does not appear to have one of the possible benefits of the real hormone - protection against mental decline.

Some research has suggested that taking estrogen reduces the risk of getting Alzheimer's disease for post-menopausal women.

In a study reported in Thursday's New England Journal of Medicine, researchers looked at the effect of an estrogen alternative, Evista, on mental ability. Evista, an osteoporosis drug also known as raloxifene, mimics estrogen in strengthening bones but without the increased risk of breast cancer.

In the study, 7,478 women with osteoporosis were given either one of two doses of Evista or a dummy pill for three years. They were periodically given a series of tests that measure such things as memory, concentration and learning.

The researchers concluded that Evista did not have an overall effect on cognitive function. There was some evidence that Evista may slightly lower the risk of decline in word memory and attention in women over 70, but more study is needed, they said.

The study was conducted by researchers at the University of California at San Francisco and San Diego and at Eli Lilly, which makes Evista and principally financed the study. Some of the researchers have received other research support from Lilly or other drug makers.

In an accompanying editorial, Dr. Richard Mayeux of Columbia University College of Physicians and Surgeons said the results of the study and related tests of estrogen are discouraging but not conclusive, and it is too soon to rule out a benefit.

``Estrogen has a critical role in the developing brain, and estrogen, or the lack of it, is likely to be equally important in the aging brain,'' he wrote.

Results of estrogen studies have been mixed, but taken together they suggest the hormone reduces the risk of Alzheimer's disease by about 30 percent.

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