A large new study has concluded that women who took estrogen-only hormone therapy later in life had Really less evidence of Alzheimer’s disease in their brains and were less frequently diagnosed with dementia. The research, published in the journal Neurology, reviewed information from over 21,000 women including autopsy results and clinical data, and is one of the most detailed investigations so far into the links between this type of hormone therapy and brain conditions. Researchers analyzed two large datasets, which in conjunction recorded cognitive testing, biomarkers, and in close to 3,000 cases, post-mortem brain examinations.
Women who used estrogen-only therapy had approximately 39 percent lower odds of a clinical diagnosis of dementia compared to women who did not use the therapy. The women also had 35 percent lower odds of exhibiting major Alzheimer’s pathology at autopsy (namely, the development ofamyloidplaques and tau tangles).
It is unclear whether the biomarker testing while still living showed the same results of decreased amyloid among therapy users. The mean age of initiation of HT for women in the study was over 70 years of age, putting these results in a very different context than earlier studies that examined HT at the time of menopause. Our analysis examined use of estrogen alone regimens, since these are generally given to hysterectomized women, on which earlier work had expressed concern about differential risks of combined estrogen plus progestin therapy.
The lead researchers, including Stanford Medicine’s Jennifer Bruno, were careful to point out that the finding represents an association, not proof that taking estrogen-only treatment can actually ward off dementia. Many other factors play a role in brain aging, and estrogen users may differ from non-users in other lifestyle and medical factors.
Even so, each of the three meansclinical diagnosis, Living Biomarkers, and the brain studyall point to the same conclusion. Of those women whose brains were examined after death, 18% of those who had taken estrogen-only treatment showed no pathological evidence of Alzheimer’s disease, versus 10% of the non-users. Conversely, 40% of the therapy users had all three of the hallmarks of Alzheimer’s disease present, against 51% of the non-users. These findings come on the heels of a long and complex history of research examining menopausal hormone therapy and cognitive function. Several landmark studies from over two decades ago cast a long shadow of caution about hormone therapy use, In particular when it is initiated later in life.
Subsequent work has come to be quite inconsistent, but has suggested that timing, formulation, and individual health status may play a role. This newest evidence supports the hypothesis that estrogen-only therapy may be tied to better brain health in some women. Women are estimated to have approximately 2 the lifetime risk of Alzheimer’s disease as men, and this has been a source of confusion for many years over what the relative role of hormonal dysregulation in sex after menopause may play. Estrogen has an effect on very many pathways in the brain, including those mediating inflammation, neuronal resilience and removal of toxic proteins.
