Does Menopause Hormone Therapy Raise Dementia Risk?Two Kinds of Studies, Two Answers

If you take hormone therapy for hot flashes or are considering it, a headline linking it to dementia can be alarming. Two very different studies point in different directions. Here is what each one found and why they differ.

The Danish registry study (2023)

Researchers used Danish national health records for women who were 50 to 60 in 2000. They compared about 5,600 women later diagnosed with dementia with about 56,000 similar women without dementia.¹

• Women who had used estrogen plus a progestogen had a 24% higher rate of dementia than women who never used hormone therapy.¹
• The longer the use, the higher the rate, from about 21% higher for a year or less to 74% higher for more than 12 years.¹
• The link held for continuous and cyclic regimens, for women who started at 55 or younger, and for Alzheimer’s disease.¹

The key limit: this kind of study shows a link, not cause. The authors said more research is needed to tell whether hormone therapy itself raises risk or whether women who need hormone therapy differ in ways that also affect dementia risk.¹

The KEEPS randomized trial follow-up (2026)

The Kronos Early Estrogen Prevention Study randomly assigned healthy, recently menopausal women to an estrogen pill, an estrogen patch (both with progesterone) or placebo for four years.² Ten years later, researchers scanned the brains of 266 participants.²

• Brain amyloid (a marker linked to Alzheimer’s) and brain structure on MRI didn’t differ between the hormone and placebo groups.²
• The researchers found no evidence of harm or benefit, and noted the results match neutral findings on thinking skills in the same group.²

The key limit: the trial was smaller, included only healthy women who started soon after menopause, and used hormones for four years.

Putting it together

• Randomized trials are better at showing cause, but this one was small and looked at short-term use in healthy women.
• Registry studies are large but can’t fully rule out other explanations.
• Longer use was linked to a higher rate in the Danish study.¹ The trial tested four years.²

Questions to ask

1. What’s the main reason I’m taking hormone therapy, and is it still helping?
2. How long should I plan to take it?
3. Do my family history and other risks change the picture?
4. Is a patch or a different progestogen a better fit for me?

Our guides to whether hormone therapy is safe, brain fog in menopause, estrogen pills versus patches and stopping hormone therapy cover related decisions.

Try: “I read about a study linking hormone therapy and dementia. I’ve been on it for six years. Can we review whether I still need it?”

My Body Changed. Now What? includes a Visit Brief. Use it to list how long you’ve used hormone therapy, why, and your questions. See the book.