Could HRT Actually Prevent Alzheimer’s if Taken at the Right Time?

There have been several well-conducted studies that show there’s an increased risk for dementia (along with cancer and cardiovascular events) associated with the use of hormone replacement therapy (HRT). In spite of this there have also been cases reported where there was a reduced risk for dementia in women using HRT. To investigate this further, a prospective study has now been reported in the Annals of Neurology that explores the relationship between the timing of HRT and the onset of dementia.

Over 5,000 postmenopausal women aged between 40 and 55 from an integrated healthcare program, who were free from dementia, were questioned about their use of HRT. Thirty years later the investigators determined the participants’ present HRT use, using pharmacy databases. When the subjects reached an average age of 80 the frequencies of dementia were assessed, using diagnoses by neurologists, neuropsychologists, and internists; the period of assessment covered an average of 7½ years.

A total of 1,524 women (27%) were diagnosed with dementia during the follow-up period. Compared to women who never took HRT, those who took it only at midlife (i.e. at enrollment) had a 26% decreased risk for dementia diagnosis. On the other hand, those who did not report taking HRT at enrolment but had evidence of later-life use had a significantly increased risk of a subsequent dementia diagnosis. Women who had used HRT in both midlife and later life had similar risks to those of women who had never reported taking it.

There are weaknesses in this study. For instance, the initial estimate of HRT use was obtained by self-reporting. Nevertheless, the findings support those outlined in my opening sentences, namely that HRT use in midlife may be protective against dementia, whereas use in late life may increase the risk for dementia. Once again we have to await confirmation of this in other studies. However, even if substantiated, the findings may only provide researchers with new clues as to the underlying causes of dementia; they will not serve as support for increased use of HRT, because of the other adverse effects.