Brain and cognition. Is there any case for improving cognitive function in menopausal women using estrogen treatment?

In the 1990s, estrogens were thought to protect the aging brain. Large randomized controlled studies, however, showed that estrogens did not treat dementia symptoms and even increased risk for dementia in older women. These findings contrast with earlier positive findings, including a wealth of cell culture and animal data all suggesting that estrogens could be a prophylactic treatment for dementia. Observational data had also suggested a significantly decreased risk for dementia in women who had been treated with estrogens for menopausal symptoms in midlife. This review discusses the "Critical Window", Healthy Cell Bias' and "Limited Duration" hypotheses, and forms of bias (healthy user, recall and survivor bias) and potential mediators (e.g., body mass, genetics) to attempt to explain the differences seen between the studies. On the basis of limited data, we conclude that estrogens only have limited positive effects on some tests for a number of months regardless of age. These effects were seen in recently menopausal women, but also in women with dementia, who are at least 15 years past the average age of menopause. In addition, after a longer period of time, treatment may confer risk, especially in older women. From this it would follow that longer term treatment with estrogens to maintain cognitive function is not indicated for older women. Whether there still is a case to treat surgical menopausal women with estrogens for a longer or shorter period of time remains to be tested.