Turns out, hormone replacement therapy could have some benefits for your brain health.
Reviewed by Dietitian Madeline Peck, RDN, CDN
Key Points
- Hormone replacement therapy (HRT) was linked to a 10% lower dementia risk in this study.
- Women who started HRT between ages 46 and 56 saw the strongest brain health benefits.
- HRT’s impact on dementia risk may depend on timing, genetics and individual health factors.
Women are more likely to develop dementia than men, and understanding why has been a major goal for researchers in recent years. One potential explanation could be hormonal changes—estrogen does a lot for the brain. It supports how neurons connect, how the brain uses energy and how it protects itself from inflammation.
When estrogen levels shift during menopause, that may be more than just a simple hormonal shift. Researchers question whether it may also be a moment that matters for long-term brain health. So it’s a reasonable question to ask: Could hormone replacement therapy play a role in reducing dementia risk? A new large-scale study set out to cut through the noise and find out which women, if any, might benefit most, and the results were published in Alzheimer’s & Dementia.
How Was the Study Conducted?
Researchers used information from the UK Biobank, a large-scale health database that tracks the wellbeing of hundreds of thousands of people over time. For this study they focused on 183,450 postmenopausal women and followed them for an average of 13 years.
To analyze the data, the team used a statistical modeling approach suited to tracking whether an exposure like hormone replacement therapy (HRT) relates to an outcome over time. The models were adjusted for a range of known dementia risk factors, including age, education, smoking status, blood pressure, BMI, cholesterol, ethnicity, diabetes and medication use, to help reduce the chance that other variables were driving the results.
The researchers also took a more granular approach than most previous studies by examining how outcomes varied across distinct subgroups. They looked at menopause type (natural versus surgical) as well as whether women carried the APOE ε4 gene variant, the strongest common genetic risk factor for dementia. Lifetime estrogen exposure, measured as the span between a woman’s first period and menopause, and the age at which women started HRT were also factored in. The aim was to understand whether certain groups of women responded to HRT differently than others.
What Did the Study Find?
Overall, women who used HRT for at least a year had a 10% lower risk of all-cause dementia—the risk went from a rate of about one in 48 to one in 43. It’s a modest reduction across the whole group, but the more interesting findings came when the researchers zoomed in on specific subgroups.
The strongest link appeared in women who had undergone surgical menopause, such as removal of the ovaries or a hysterectomy. For them, the risk of dementia was 26% lower—reducing the risk from one in 39 women to one in 44. Women with the APOE ε4 variant appeared to have a 13% lower risk of dementia if they used HRT (from affecting one in 23 women to one in 21 women), while women with fewer years of estrogen exposure over their lifetime appeared to have a 16% lower risk (with the risk lowering slightly from two in 87 women to two in 88).
Timing mattered too. Women who started HRT between the ages of 46 and 56 saw the greatest benefit. Starting earlier than 46 or later than 56 wasn’t linked to reduced risk, which supports the idea of a “window of opportunity” when the brain may respond best to hormones.
When the researchers looked at dementia types, HRT was linked to a lower risk of Alzheimer’s disease specifically. However, there was no clear benefit for non-Alzheimer’s forms of dementia across the group as a whole. So the protective link seems to lean toward Alzheimer’s rather than dementia in every form.
Limitations
There are some limitations to consider when interpreting this data. This was an observational study, which means it found associations rather than proof of cause and effect. HRT wasn’t shown to prevent dementia, only to be linked with lower risk. There’s also the issue of healthy-user bias. Women who choose HRT may differ from those who don’t in ways that affect their health, such as lifestyle or access to care. The researchers adjusted for many of these factors, but they couldn’t rule out every hidden influence.
The study didn’t have data on the type of HRT women used, whether it was estrogen alone or combined with progestogen, or how it was taken. That’s a meaningful gap because formulation may shape the results. The participants were also mostly white women of European descent, so the findings may not apply equally to everyone. And because dementia diagnoses came largely from hospital records, milder cases may have been missed.
How Does This Apply to Real Life?
If you’re approaching menopause or thinking about HRT, this study offers something useful to bring to a conversation with your doctor. It doesn’t hand you a simple yes or no, but it does suggest that the picture is more personal than one-size-fits-all.
The findings hint that certain women may have more to gain. If you’ve had surgical menopause or carry the APOE ε4 gene variant, the potential brain benefit appears potentially stronger. Timing looks important too, with the mid-forties to mid-fifties standing out as the period when HRT was most associated with lower risk.
None of this means HRT is right for everyone, and it shouldn’t be started for brain health alone based on this evidence. HRT carries its own risks and benefits that depend on your personal health history. The takeaway is that these are questions worth raising, and this research gives you and a healthcare provider more information to work with when weighing the decision.
Our Expert Take
This study published in Alzheimer’s & Dementia followed more than 183,000 postmenopausal women in the UK Biobank for over 13 years and found that HRT use was linked to a 10% lower risk of dementia, with stronger associations in women who had surgical menopause or started HRT between ages 46 and 56. While the results can’t prove cause and effect, they build a solid case that HRT’s relationship with brain health may depend heavily on who’s taking it and when, pointing toward a future where HRT prescribing is tailored more closely to each woman’s individual risk.