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Hormone replacement therapy and dementia: what the studies report
Women make up most people with Alzheimer's, and the drop in oestrogen at menopause has long been suspected to play a part. This page shows what the library holds on hormone therapy.
- 86studies in the library match, of 30,180
- 41name it in the title
- 1991–2026years published
- 85peer-reviewed articles
The query: title or abstract mentions "hormone therapy", "hormone replacement therapy", "HRT", "menopausal hormone", "estrogen/oestrogen replacement/therapy/treatment/plus progestin", "conjugated equine estrogens" or "Women's Health Initiative", matched case-insensitively against each record's title and abstract (its summary field) in alzhub's library of 30,180 study records, as of 2026-11-10. Every count on this page comes from that match. The matched list as JSON.
Observational studies once suggested that women taking hormone replacement therapy after the menopause developed Alzheimer's less often. A large randomised trial in older women then found the opposite, more dementia in those given hormones, which changed practice. Since then the research has turned to timing: whether starting hormones close to the menopause has a different effect from starting them years later, and whether the type of hormone matters.
This page describes what published research in alzhub's library reports. It is not medical advice and does not apply to any one person: a doctor who knows the person's history is the only one who can say what a result or a treatment means for them.
What the studies report, in their own words
Whole sentences copied from the abstract or key findings of the highest-scoring matched studies, chosen because they mention the subject and give a figure. 8 of the 86 matched records are quoted; each links to its study page and from there to the paper.
“More women in the estrogen plus progestin group had a substantial and clinically important decline (> or =2 SDs) in Modified Mini-Mental State Examination total score (6.7%) compared with the placebo group (4.8%) (P =.008).”
“For CEE alone, younger women (aged 50-59 years) had more favorable results for all-cause mortality, myocardial infarction, and the global index (nominal P Conclusions and relevance Menopausal hormone therapy has a complex pattern of risks and benefits.”
“The adverse effect of hormone therapy was more pronounced among women with lower cognitive function at baseline (all P 2 SDs) was estimated to be 1.47 (95% confidence interval, 1.04-2.07).”
“Hormone therapy was not associated with PiB SUVR in the APOEɛ4 non-carriers.”
“Conclusions Conjugated equine estrogens with or without MPA are associated with greater brain atrophy among women aged 65 years and older; however, the adverse effects are most evident in women experiencing cognitive deficits before initiating hormone therapy.”
“Overall, 61 women were diagnosed with probable dementia, 40 (66%) in the estrogen plus progestin group compared with 21 (34%) in the placebo group.”
“When combined hormone therapy (n=2196) was compared with placebo (n=2189), there was a significant increase in the number of major cardiovascular events (7 v 0, P=0.016) and venous thromboembolisms (22 v 3, hazard ratio 7.36 (95% CI 2.20 to 24.60)).”
“Associations of p-tau217 with dementia were larger in magnitude for women randomized to estrogen plus progestin (HR, 4.18; 95% CI, 3.41-5.13) vs placebo (HR, 3.07; 95% CI, 2.41-3.91) (P for interaction = .04) but did not significantly vary by estrogen alone vs placebo.”
What kind of evidence it is
By study design
| Design (as recorded) | Studies |
|---|---|
| Systematic review or meta-analysis | 10 |
| Randomised controlled trial | 3 |
| Cohort or longitudinal study | 13 |
| Case-control study | 2 |
| Cross-sectional study | 3 |
| No design recorded | 55 |
The design is the one named in alzhub's record for the study; a record with none is counted as "no design recorded".
By year
| Year | Studies | Share |
|---|---|---|
| 2026 | 3 | |
| 2025 | 5 | |
| 2024 | 0 | |
| 2023 | 2 | |
| 2022 | 1 | |
| 2021 | 3 | |
| 2020 | 1 | |
| 2019 | 0 | |
| 2018 | 0 | |
| 2017 | 5 | |
| 2016 and earlier | 66 |
Other counts within the matched set
| Peer-reviewed articles | 85 |
| Marked open access in the record | 11 |
| Rated "high" evidence strength in alzhub's summary | 32 |
| Rated "moderate" evidence strength in alzhub's summary | 18 |
| Rated "low" evidence strength in alzhub's summary | 36 |
| Records stating a participant count | 32 |
| Median participants (those records) | 1,035 |
| Largest participant count | 3,142,673 |
Within the 86 matched studies
| Studies… | Count | Rule |
|---|---|---|
| …that mention the Women's Health Initiative | 18 | the abstract also contains "Women's Health Initiative" or "WHI/WHIMS" |
| …that discuss timing or a critical window | 12 | the abstract also contains "timing", "critical window" or "window of opportunity" |
| …that are randomised trials or mention one | 26 | the abstract also contains "randomised" or "placebo" |
The 10 highest-scoring matched studies
Title matches first, then by alzhub's usefulness score, which rates a study's design, journal, evidence and recency, not whether its result is good news.
- Alzheimer's blood-based biomarkers, incident dementia, and interactions with age, APOE status, and hormone therapy
- Effect of estrogen plus progestin on global cognitive function in postmenopausal women: the Women's Health Initiative Memory Study: a randomized controlled trial
- Menopausal hormone therapy and health outcomes during the intervention and extended poststopping phases of the Women's Health Initiative randomized trials
- Conjugated equine estrogens and incidence of probable dementia and mild cognitive impairment in postmenopausal women: Women's Health Initiative Memory Study
- Conjugated equine estrogens and global cognitive function in postmenopausal women: Women's Health Initiative Memory Study
- Postmenopausal hormone therapy and regional brain volumes: the WHIMS-MRI Study
- 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
- Long-term hormone therapy for perimenopausal and postmenopausal women
- Estrogen therapy in postmenopausal women: effects on cognitive function and dementia
- Main morbidities recorded in the women's international study of long duration oestrogen after menopause (WISDOM): a randomised controlled trial of hormone replacement therapy in postmenopausal women
Systematic reviews and meta-analyses in the set
10 of the matched records are recorded as a systematic review, meta-analysis or umbrella review; the highest-scoring not already listed above:
- Evidence-based prevention of Alzheimer's disease: systematic review and meta-analysis of 243 observational prospective studies and 153 randomised controlled trials
- Treatment of Symptoms of the Menopause: An Endocrine Society Clinical Practice Guideline
- Postmenopausal hormone replacement therapy: scientific review
- Hormone replacement therapy and cognition: systematic review and meta-analysis
- Risk factors associated with the onset and progression of Alzheimer's disease: A systematic review of the evidence
Newest matched studies
- Associations of menopause hormone therapy with late-life cognition and brain health vary by formulation and APOEε4 presence
- Plasma Phosphorylated Tau 217 and Incident Mild Cognitive Impairment and Dementia in Older Women
- Menopause hormone therapy and risk of mild cognitive impairment or dementia: a systematic review and meta-analysis
- Hormone replacement therapy in women and vascular risk factors modify the association of a multi‐ancestry polygenic risk score with Alzheimer disease and related traits
- The 2024 UK clinical guideline for the prevention and treatment of osteoporosis
Journals with the most matched studies
| Journal | Studies |
|---|---|
| JAMA | 12 |
| Neurology | 10 |
| Alzheimer's & dementia : the journal of the Alzheimer's Association | 3 |
| Menopause (New York, N.Y.) | 3 |
| Neurobiology of aging | 3 |
Questions
- Does hormone replacement therapy prevent Alzheimer's?
- The largest randomised trial, in women who started hormones well after the menopause, found more dementia, not less. Whether starting earlier is different is the open question the newer studies on this page address; none of this is a reason to start or stop treatment without a doctor.
- How many studies on hormone therapy (hrt) and dementia does alzhub hold?
- 86 of the 30,180 study records in alzhub's library match the query "title or abstract mentions "hormone therapy", "hormone replacement therapy", "HRT", "menopausal hormone", "estrogen/oestrogen replacement/therapy/treatment/plus progestin", "conjugated equine estrogens" or "Women's Health Initiative""; 41 of them name it in the title. Counted from the records when this page was built.
- What kinds of study are they?
- 10 systematic review or meta-analysis, 3 randomised controlled trials, 13 cohort or longitudinal studys, 2 case-control studys, 3 cross-sectional studys; 55 record no design.
- What is the most recent study in the set?
- "Associations of menopause hormone therapy with late-life cognition and brain health vary by formulation and APOEε4 presence" (medRxiv (preprint), 2026), the newest by publication date among the matched records.
- Which journals publish most on it?
- JAMA (12); Neurology (10); Alzheimer's & dementia : the journal of the Alzheimer's Association (3), counted across the matched records.
Read on
- Why are more women affected?The question behind this research.
- PreventionLifestyle trials and their results.
- Risk factors, rankedSex and hormones among the risks.