Tests carried out on 16 young women during their menstrual cycle showed that levels of recollection were constant throughout.

During the mid-luteal phase (with high oestrogen levels), the women did better on tests that didn’t rely on recalling specific events or objects than they did during the early follicular stage, when hormone levels are lower (Neuropsychologia, 2002; 40: 518-29).

* At Scripps Institute in California, other scientists have found, at least in rats, that the male hormone testosterone on its own or with oestrogen, rather than oestrogen alone, may be important in preventing Alzheimer’s.

Testosterone appears to prevent some of the protein abnormalities causing the neurofibrillary tangles found in the brain of Alzheimer’s patients (Proc Natl Acad Sci USA, 2002; 99: 1140-5).