Oestrogen plus progestin doubles the risk of dementia in post-menopausal women Shumaker S, Legault C, Rapp S et al. Estrogen plus progestin and the incidence of dementia and mild cognitive impairment in postmenopausal women: the women's health initiative memory study: a randomized controlled trial.

5the beneficial effect of estrogen on psychological and cognitive function. We need to await the outcome of the unopposed arm of the WHIMS trial to determine whether medroxyprogesterone acetate was influential in the negative findings of the hormone therapy arm of this study. Second, 80% of the WHIMS sample were hormone naive, and started hormone therapy at a mean age of approximately 70 years. Both animal and human studies provide evidence that estrogen protects cognitive function when treatment is initiated soon after ovariectomy in rats 6