Assumptions about the protective effect of oestrogen may have been overstated. New information, while far from conclusive, suggests that postmenopausal women with higher levels of circulating endogenous oestrogen experience greater cognitive decline.
In more than 500 women who were not taking HRT and who participated in the study, cognitive function was measured by a battery of tests. While there was a tendency for women with higher levels of oestrogen to perform poorly on these tests, the results were not consistent, suggesting the need for further research (J Am Geriat Soc, 1998; 46: 816-21).