- A 2023 study finds that early menopause may increase your risk of developing Alzheimer’s disease.
- Taking hormone therapy may help offset that risk, according to the study.
- Hormone therapy has a controversial past, but experts stress the importance of its help with menopausal symptoms.
About 411,100 Australians have Alzheimer’s disease and related dementias, and nearly two-thirds (63%) of Australians with dementia are women.
Now, a new study has found that the age when women start menopause may be a factor in the development of Alzheimer’s disease, but menopausal hormone therapy (MHT) could help offset that risk.
The study, which was published in JAMA Neurology, analysed brain scans from 193 women and 99 men who did not have a diagnosis of Alzheimer’s or other forms of dementia to look for signs of beta-amyloid plaques and tau proteins, two markers of Alzheimer’s disease.
The researchers discovered that women in general had more build-up of tau in several parts of the brain than men of the same age, along with more amyloid plaques. All of the women in the study used some type of menopausal hormone therapy, which is a mix of oestrogen and progestin, a synthetic form of the hormone progesterone. The findings suggested that women who went into menopause before age 40, from age 40 to 45, or who started menopausal hormone therapy more than five years after they started menopause had higher levels of tau in their brains.
But the researchers also found that people who started MHT around the time they began menopause didn’t have an increased risk for developing tau proteins in the brain, suggesting that the menopause treatment may temper the risk of developing Alzheimer’s disease.
Ultimately, the researchers concluded that going into menopause at an earlier age and starting hormone therapy late after menopause has begun could contribute to how much tau a woman develops in her brain.
The average age that women go through menopause is 51, according to the American College of Obstetricians and Gynecologists (ACOG), but some women may start menopause before age 40.
Research into the relationship between menopause and Alzheimer’s disease is ongoing, and there’s also a controversial history behind menopausal hormone therapy. With that, you probably have some questions. Here’s what we know so far.
Does early menopause raise a woman’s odds for dementia?
Data has linked early menopause to an increased risk of developing dementia later in life. One study published last year found that women who started menopause around age 45 were 30% more likely to be diagnosed with dementia before age 65 when compared to women who started menopause at 50.
Neurologist Dr Verna Porter says that early menopause “may be an important sex-specific risk factor for Alzheimer’s disease,” but more research is needed.
There are also other risk factors that are thought to be involved in the development of Alzheimer’s. According to the US National Institute on Aging (NIA), those can include:
- Genetics
- Heart disease
- High blood pressure
- Stroke
- Diabetes
- Obesity
Does oestrogen deficiency cause Alzheimer’s?
When a woman goes through menopause, oestrogen levels drop, triggering classic symptoms like hot flashes, mood swings, and vaginal dryness, ACOG explains. With that, some researchers have theorised that lowered oestrogen levels may lead to the development of Alzheimer’s, it just hasn’t been definitively proven. Researchers have found that low oestrogen levels over longer periods of time can cause oxidative stress, which could impact cognitive function.
“This is what we know: oestrogen absolutely has a profound effect on the brain,” says professor of obstetrics and gynaecology Dr Lauren Streicher. “There are oestrogen receptors throughout grey and white matter and you can see changes in women who are post-menopausal.”
But Dr Streicher says that things “get a little sticky when you look at Alzheimer’s disease” and hormone therapy. “People are hesitant to say, Take hormone therapy to prevent Alzheimer’s— not because it isn’t necessarily true, but because it hasn’t been proven yet,” Dr Streicher says. “But this data does not surprise me. We know that oestrogen has a profound impact on the brain. This may be further indication that taking hormone therapy early can potentially prevent the risk of Alzheimer’s disease down the road.”
There is data to support oestrogen therapy in the case of a woman having her ovaries removed, says professor of obstetrics and gynaecology Dr Mary Jane Minkin. “If a woman has her ovaries out before the age of 45 and does not get replacement with oestrogen, we have pretty good data that her risk of dementia is significantly increased,” she says. “The question is what about a woman at age 51 who goes through menopause: does giving oestrogen to her prevent dementia? It’s much less clear and controversial.”
Dr Porter calls the study “intriguing,” adding, “the findings of this study may inform Alzheimer’s disease risk discussions relating to female reproductive health and treatment.”
There is controversy surrounding MHT, but doctors say there shouldn’t be
At a basic level, menopausal hormone therapy (formerly known as hormone replacement therapy) involves taking oestrogen and possibly progestin to replace hormones that your body loses during menopause, ACOG explains.
Hormone therapy has been found to be the best treatment for hot flashes and night sweats, along with vaginal dryness and bone loss, per ACOG. However, preliminary results were published in 2003 from the Women’s Health Initiative clinical trial that linked a combination of oestrogen and progestin with an increased risk of heart disease, stroke, blood clots, dementia, and breast cancer, and the study was stopped early as a result.
But the findings were later debunked. Researchers found that the original study looked at women who were aged 65 and up who already had a greater risk of heart attack, stroke, blood clots, and more, skewing the data. The study also didn’t factor in how old these women were when they started hormone therapy.
Since then, data has shown that using oestrogen with a particular form of progesterone may increase the risk of breast cancer, but not oestrogen alone. “Micronised progesterone is preferable since it’s not associated with breast cancer,” Dr Streicher says.
And, again, timing of MHT matters. “If women start hormone therapy late—more than 10 years after the onset of menopause—the damage may already be done, whether it’s tau proteins or changes in vascularity,” Dr Streicher says.
Dr Porter agrees. “These findings are consistent with clinical guidelines that suggest hormone therapy is relatively safe when used close to the onset of menopause, but may pose an increased risk for progression to Alzheimer’s disease dementia if initiated later,” she says.
Dr Streicher urges women to look into the data on hormone therapy. “You are far more likely to die of heart disease than breast cancer from hormone therapy,” Dr Streicher says.
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