Fewer hot flashes and night sweats may not be the only upside.
A new study suggests women taking a drug used to ease menopause symptoms may also face a lower risk of developing Alzheimer’s disease.
The finding comes as scientists continue to investigate why women are more likely than men to develop the memory-robbing illness, with research indicating that their longer lifespan alone doesn’t fully account for the higher risk.
The study looked at estrogen-based menopausal hormone therapy, or MHT — a prescription treatment that replaces estrogen after the body’s natural levels of the hormone plummet during the so-called “change of life.”
For women dealing with uncomfortable symptoms related to the menopause transition, MHT can offer some much-needed relief. But researchers at Stanford University wanted to know whether it may also have an effect on the brain.
After all, MHT has had a complicated history. Some earlier studies raised alarms that the treatment could increase the risk of dementia, especially when women started taking it later in life.
The latest research, however, paints a very different picture.
Scientists dug into two existing databases containing information on more than 21,000 women whose brains were examined after their deaths.
They were looking for two telltale signs of Alzheimer’s: amyloid plaques and neurofibrillary tangles. These abnormal proteins can gum up communication between brain cells and eventually contribute to cell death.
The researchers then compared brain autopsies from 258 women who had reported taking estrogen-only MHT with those from roughly 2,701 women who had never used the treatment.
They found that women who had taken estrogen-only MHT had a 35% lower risk of developing Alzheimer’s during their lifetime than those who had not taken the medication.
“MHT appears to exert a modest but meaningful and statistically significant protective effect on the risk of developing Alzheimer’s pathology,” Dr. Jennifer Bruno, co-author of the study, said in a press release.
“While this is by no means more powerful than such very well-known factors as age, possession of the genetic variant knowns as APOE4 or a history of hypertension, it’s nonetheless quite a consistent effect, spanning multiple Alzheimer’s-related outcomes.”
But the results don’t apply to every form of MHT.
Estrogen-only MHT is generally prescribed to women who have had hysterectomies. That’s because taking estrogen by itself can cause the uterine lining to thicken, raising the risk of uterine cancer. Women who still have a uterus typically take progesterone alongside estrogen to protect that tissue.
The potential brain benefit of estrogen-only MHT could have implications for roughly one-third of women of menopausal age. By age 60, more than 30% of women have had hysterectomies and no longer have a uterus.
“The recent medical literature suggests that MHT is more beneficial when initiated during or soon after menopause,” said Dr. Hadi Hosseini, the study’s senior author.
“The women in our study tended to be older. If anything, our finding underestimated the benefit due to their late initiation of therapy.”
Still, the study has some important caveats. Researchers didn’t have enough data to determine whether estrogen-plus-progestin MHT has the same potential benefit, and women using topical estrogen weren’t included.
The findings also only show an association, not proof that the treatment itself prevents Alzheimer’s.
Even so, it offer an intriguing new twist in the long-running debate over how menopause treatments affect women’s bodies.
“For a long time,” Bruno said, “the going recommendation was ‘Don’t use MHT for memory decline.’ This study flies in the face of that recommendation.”
Why women face a higher Alzheimer’s risk
Across the country, more than 7 million Americans age 65 and older are living with Alzheimer’s, and nearly two-thirds of them are women. Scientists are still working to understand that disparity, but several theories have been proposed.
One of the leading hypotheses is that women tend to live longer than men, and older age is the biggest known risk factors for Alzheimer’s. In the US, the average life expectancy for women is 81.4 years, compared with 76.5 for men.
But longevity doesn’t seem to explain the whole difference.
Genetics are also thought to play a role. Studies have suggested that APOE4 — the strongest known genetic risk factor for late-onset Alzheimer’s — may affect women differently than men and could help widen the sex disparity.
Other research has found that women may also be more vulnerable to certain health conditions linked to cognitive decline, including high blood pressure and obesity.
And then there’s estrogen.
The hormone does more than regulate the reproductive system — it also plays a role in the brain. Some experts believe the dramatic drop in estrogen during menopause may take away some of that protection, potentially leaving the brain more vulnerable to dementia.
Whatever the reason, the gender gap could become even more pronounced as Alzheimer’s cases climb.
By 2060, the number of Americans living with the disease is projected to reach 14 million. An estimated 8.5 million of them — roughly 61% — will be women.
