The “oestrogen only” treatment arm of the women's health initiative memory study shows that oestrogen does not protect against mild cognitive impairment or dementia and slightly increases the risk, say two reports published in JAMA (2004;291: 2947-58, 2959-68).Mild cognitive impairment strongly predicts dementia.

Previous studies have suggested that oestrogen might prevent cognitive decline, said Lon Schneider, professor of psychiatry, neurology, and gerontology at the University of Southern California in Los Angeles, who commented on the …