HRT, Menopause and Alzheimer’s: What the New Research Is Telling Us

There has been a lot of discussion over the years about HRT and dementia, and many women are still worried because they remember being told that HRT could increase the risk of Alzheimer’s disease. The newer research is giving us a much more detailed picture, and although we are not yet at the point where we can say that HRT prevents Alzheimer’s, the evidence is becoming increasingly reassuring about HRT started around the time of menopause.

1. Estrogen-only HRT and Alzheimer’s changes in the brain

A Stanford study published in Neurology in August 2026 was particularly interesting because the researchers did not simply look at whether women had been diagnosed with dementia; they were also able to examine actual brain tissue after death and look for the characteristic changes of Alzheimer’s disease, including amyloid plaques and neurofibrillary tangles.

Among the women studied, those who had used estrogen-only HRT had around 35% lower odds of Alzheimer-type brain pathology and around 39% lower odds of having been diagnosed with dementia during life compared with women who had not used HRT.

This does not prove that estrogen prevented Alzheimer’s because it was an observational study, and estrogen-only HRT is most commonly used in women who have had a hysterectomy. It also does not tell us whether the same findings would apply to the modern combination many women use today, such as transdermal estradiol gel or patches with micronised progesterone.

2. The age you reach menopause may matter

Another study published in JAMA Network Open followed more than 2,600 women and found that earlier menopause was associated with faster cognitive decline, faster decline in episodic memory, earlier Alzheimer’s diagnosis, greater accumulation of white matter changes on MRI and slightly faster loss of brain volume.

One finding that stood out was that, among women who went through menopause naturally, reaching menopause five years earlier was associated with about 15% greater accumulation of white matter hyperintensities over the following decade.

This does not mean that early menopause directly causes Alzheimer’s disease, but it does suggest that the age at which ovarian hormone exposure comes to an end may be relevant to long-term brain health.

3. The very large UK Biobank study

A third study looked at 183,450 postmenopausal women who were followed for an average of just over 13 years. Compared with women who had never used HRT, women who had used it for at least a year had around a 10% lower risk of all-cause dementia and a 16% lower risk of Alzheimer’s disease.

The association appeared particularly interesting in women who had experienced surgical menopause, where HRT use was associated with around a 26% lower risk of all-cause dementia, and the timing of treatment also seemed to matter.

Women who started HRT between approximately 46 and 56 years of age appeared to have the greatest reduction in dementia risk, whereas starting it later did not show the same association. This fits with what we have been discussing for some time as the window of opportunity, where replacing hormones close to the time they are naturally being lost may have very different effects from starting HRT many years after menopause.

4. What about the old study saying HRT caused dementia?

This is where much of the confusion comes from. The Women’s Health Initiative Memory Study, or WHIMS, is still frequently quoted when people say that HRT increases dementia risk, but most of those women were 65 years or older when treatment was started, and the adverse dementia signal was particularly associated with conjugated equine estrogen combined with medroxyprogesterone acetate.

That is quite different from a woman starting modern HRT during perimenopause or around the natural age of menopause, which is why we should be careful about applying the WHIMS findings to every woman considering HRT today.

5. Does modern HRT actually prevent Alzheimer’s?

We still cannot say that it does.

The KEEPS trial is useful because it included recently menopausal women who were randomly assigned to treatment that included transdermal 17β-estradiol with micronised progesterone, which is much closer to the HRT commonly prescribed today. When researchers looked at brain imaging around ten years later, there was no significant difference in amyloid or structural MRI markers between the HRT and placebo groups.

That study did not show that HRT prevents Alzheimer’s, but importantly, it also did not show evidence that modern HRT was damaging the brain.

6. What does this mean if you are considering HRT?

If you have menopausal symptoms and HRT is otherwise appropriate for you, I do not think fear of Alzheimer’s disease should automatically stop you from considering treatment. The newer evidence is increasingly reassuring about HRT started around the time of menopause, and the conversation may be particularly important for women who experience premature menopause, early menopause, removal of both ovaries or surgical menopause, because these women potentially face many more years without normal ovarian hormone exposure.

We still should not prescribe HRT solely as an Alzheimer’s prevention treatment because we do not yet have the randomised evidence needed to make that recommendation, and the Australasian Menopause Society continues to advise that it is too early to recommend HRT specifically for preventing dementia.

7. The bigger picture

What I find most interesting about this research is that the question is becoming much more sophisticated than simply asking whether HRT is “good” or “bad” for the brain. We increasingly need to think about which woman is taking it, which hormones she is using, when treatment was started, whether menopause occurred naturally or surgically, and what her underlying cardiovascular, metabolic and genetic risks are.

HRT is also only one part of looking after your brain. Blood pressure, cholesterol, blood sugar, exercise, muscle strength, sleep, hearing, smoking, alcohol intake, social connection and keeping your brain active are all important parts of reducing dementia risk.

And finally, brain fog is not the same as dementia

Word-finding difficulties, losing your train of thought, poor concentration, forgetfulness and feeling less mentally sharp are all very common during perimenopause, particularly when sleep is poor or there are hot flushes, anxiety, stress, mood changes or ADHD in the background.

Having menopause-related brain fog does not mean you are developing Alzheimer’s disease, although progressive memory problems that begin interfering with normal everyday life should always be properly assessed.

Take-home message

The newest studies do not prove that HRT prevents Alzheimer’s disease, but they are making it increasingly difficult to support the old blanket statement that HRT damages the brain. HRT started appropriately around menopause appears reassuring from a cognitive safety point of view, and large observational studies now suggest that it may even be associated with a lower risk of dementia in some groups of women, particularly those with early or surgical menopause.

For me, the question is increasingly becoming:

Which woman, which hormones, and started when?

General educational information only. HRT should always be considered according to your own symptoms, medical history, menopause history and individual risks, and you should not start, stop or change prescribed HRT solely because of headlines about dementia or Alzheimer’s disease.

1. Bruno J, Shaw J, Hosseini H, et al. Estrogen-only menopausal hormone therapy and Alzheimer-related neuropathology. Neurology. Published August 2026.

2. Campagna MP, et al. Age at Menopause and Brain Atrophy Among Older Women. JAMA Network Open. 2026;9(8). doi:10.1001/jamanetworkopen.2026.30973.

3. Squires S, Saleh RNM, Pilling LC, et al. Hormone replacement therapy and dementia risk among postmenopausal women: Identifying responsive subgroups in the UK Biobank. Alzheimer’s & Dementia. 2026;22. doi:10.1002/alz.71679.

4. Kantarci K, et al. Long-term amyloid PET and MRI outcomes in a menopausal hormone therapy trial. Alzheimer’s & Dementia. 2026;22.

5. Australasian Menopause Society. Oestrogen and cognition in the perimenopause and menopause.