Menopause marks the end of menstrual periods and is accompanied by declining estrogen levels. The drop in estrogen has been hypothesized to contribute to increased risk for Alzheimer’s disease, and investigators have been exploring how menopausal hormonal therapy influences dementia-related outcomes. A recent retrospective study published in Neurology examined associations between estrogen-only menopausal hormonal therapy and multiple Alzheimer’s-related markers.
The researchers used data from two major repositories: the National Alzheimer’s Coordinating Center (NACC) and the Alzheimer’s Disease Neuroimaging Initiative (ADNI). The NACC cohort compared 258 participants who reported using estrogen-only menopausal hormonal therapy with 2,701 participants who did not. The ADNI cohort included 110 estrogen-only users and 1,948 nonusers. The average age across cohorts was approximately 71–72 years, and a majority of participants were white.
The investigators defined estrogen-only therapy to exclude topical estrogen preparations and omitted participants reporting combined estrogen–progestin regimens. For a subset of participants, brain autopsy data were available, permitting direct examination of neuropathologic markers such as amyloid burden and other components of Alzheimer’s pathology.
On autopsy measures, participants who had used estrogen-only menopausal hormonal therapy were less likely to show increased scores for Alzheimer’s disease pathology. The study reported that estrogen-only users also had evidence of lower amyloid load, indicating a comparatively reduced burden of this core Alzheimer’s biomarker. In addition, estrogen-only therapy was associated with fewer infarcts, brain regions of tissue loss related to insufficient blood supply.
These autopsy and biomarker observations were the principal biologic findings supporting an association between estrogen-only therapy and more favorable brain pathology metrics in this retrospective analysis.
Analyses of clinical outcomes differed somewhat by dataset. In the NACC cohort, estrogen-only users had a lower likelihood of receiving a clinical diagnosis of dementia and showed less clinical decline compared with nonusers. In the ADNI cohort, estrogen-only therapy was linked to better immediate memory and learning performance.
A subgroup analysis within ADNI that focused on participants without dementia found an association between estrogen-only therapy and improved verbal memory. The researchers also conducted several exploratory subgroup analyses that considered types of estrogen-only therapy, though full details of those subgroup results were not reported in the source article.
This work was retrospective and observational, using preexisting clinical, imaging, and autopsy data from NACC and ADNI. Such study designs can identify associations but cannot establish causation. The source article notes that much more research is required to confirm whether the observed associations reflect a true protective effect of estrogen-only therapy against Alzheimer’s disease or whether unmeasured confounding or selection biases account for the findings.
Important details either not reported in the summary or not available from the datasets as described include duration and timing of estrogen exposure relative to menopause, precise formulations and doses used, and comprehensive demographic breakdowns beyond the reported majority race and mean age. The study also excluded topical estrogen and combined estrogen–progestin regimens, limiting applicability to those specific therapies.
The reported associations—lower Alzheimer’s pathology on autopsy, reduced amyloid burden, fewer infarcts, and better memory outcomes among estrogen-only users—are hypothesis-generating. They suggest that future prospective and randomized studies should investigate whether estrogen-only menopausal hormonal therapy can meaningfully alter Alzheimer’s risk or progression when given according to specific timing, dose, and formulation strategies.
Until higher-level evidence is available, clinicians should interpret these retrospective findings cautiously. Decisions about menopausal hormonal therapy should continue to be individualized, weighing known benefits and risks for each patient and considering that the current report shows association rather than proven causal protection against Alzheimer’s disease.