Large UK study links hormone therapy to lower dementia risk in some women
2026-08-26
In August 2026, a study of more than 180,000 UK women linked hormone therapy to a modestly lower risk of dementia, especially when started between 46 and 56. It shows an association, not proof, and a major 2025 review found no clear effect either way.
See a doctor if you or people close to you notice memory problems that are getting worse or affect daily life, as these need proper assessment rather than being put down to menopause.
What happened
Researchers from the University of East Anglia and the University of Exeter studied 183,450 postmenopausal women in the UK Biobank. They followed them for about 13 years. The results appeared in the journal Alzheimer's & Dementia.1,2
Women who used hormone therapy for at least a year had about a 10% lower risk of dementia overall.1,3 Their risk of Alzheimer's disease was about 16% lower.3 There was no link with other types of dementia.3
Who seemed to benefit most
The link was stronger in some groups:1,2
- Women who had surgical menopause (removal of the ovaries) had about 26% lower risk.
- Women who started hormone therapy between 46 and 56 showed the biggest reduction.
- Women with shorter lifetime exposure to their own estrogen, such as those with early menopause.
- Carriers of APOE4, a gene that raises Alzheimer's risk.
The authors said this supports more research into a “critical window” for starting treatment.3 They found no similar benefit when hormone therapy started outside the 46 to 56 age range.2
The lead researcher said the effects of hormone therapy on the brain seem complex and depend on each woman's biology.1 She linked women's higher rates of dementia partly to changes in brain metabolism around menopause.1
How this fits with other evidence
Earlier evidence has been mixed. A review published in The Lancet Healthy Longevity in late 2025 pooled studies with over a million participants.4
It found no clear evidence that hormone therapy raises or lowers dementia risk. Most of the evidence was rated low or very low certainty.4 The authors said the findings support current advice not to prescribe hormone therapy to prevent dementia.4
The review also found gaps. No eligible studies looked at women with early menopause or premature ovarian insufficiency.4 Those are some of the groups the 2026 study suggests might benefit most.
The two findings do not fully contradict each other. A modest benefit in some groups could be hidden when all women are pooled together. Only well-designed trials can settle the question.
What it means for you, and what it does not
The new study is reassuring for women who use hormone therapy for symptoms around the usual age of menopause. It adds to signs that timing may matter.
It does not prove that hormone therapy prevents dementia. The study was observational. Women who choose hormone therapy may be healthier in other ways.3 It had no data on the type, dose or form of hormone therapy, and most participants were white and better off.3
Milder dementia may also have been missed, because diagnoses came from hospital records.3 The European Menopause and Andropause Society says hormone therapy is not indicated for preventing cognitive decline or dementia.5
Short-term memory lapses and brain fog are common around menopause and usually improve. For more on memory changes, see our page on brain fog.
Related
Sources
- Study: hormone replacement therapy lowers dementia risk, Healio (2026)
- Hormone replacement therapy may reduce dementia risk for some women, News-Medical (2026)
- HRT associated with lower dementia risk in some postmenopausal women, US Pharmacist (2026)
- No evidence links menopause hormone therapy to dementia risk (Lancet Healthy Longevity review), Contemporary OB/GYN (2026)
- EMAS statement on the FDA decision to remove black box warnings from menopausal hormone therapy, European Menopause and Andropause Society (2025)