The central nervous system and HRT

In postmenopausal women, both the aging process and the hypoestrogenism due to the loss of ovarian function seem to be related to the progressive impairment of cognitive functions and to a higher risk of developing Alzheimer's disease (AD). This paper reviews the potentially beneficial effects of hormonal replacement therapy (HRT) on cognition and on the risk of developing AD. Articles relevant to the topic were selected by reviewing MEDLINE data and references of previous published reviews on this subject. Epidemiological studies on the effects of HRT on cognitive functioning have yielded disparate results, perhaps because of varying methodology and designs. However, the available data suggest that the use of HRT could be associated with a lower risk for AD. This conclusion should be interpreted with caution, since most of the studies were case-control studies, and thus subjected to several sources of bias. Further well-designed and conducted clinical trials and longitudinal studies would be required to clarify the effects of estrogens on cognition and AD.