Across the United States, roughly 6 million adults 65 and over have Alzheimer’s disease. Almost two-thirds of them are women — a discrepancy that researchers have long attributed to genetics and women’s longer life spans, among other reasons. But there is growing consensus that menopause may also be an important risk factor for the development of dementia later in life.
Women going through the life phase, which is clinically defined as the end of fertility, face as many changes in the brain as in the ovaries, said Dr Lisa Mosconi, a neuroscientist and director of the Women’s Brain Initiative at Weill Cornell Medicine. While the vast majority of women will weather these changes without long-term health consequences, about 20 per cent will develop dementia in the decades that follow.
The female brain is rich in estrogen receptors, particularly in regions that control memory, mood, sleep and body temperature, all of which “work beautifully when estrogen is high and consistent”, Dr Mosconi said. Estrogen is also vital for the brain’s ability to defend itself against aging and damage.
The characteristic decline in estrogen during menopause not only alters the functioning in some brain regions, she said, it is also thought to change the brain’s structure; scans show reduced volume in menopausal brains compared to male brains of the same age and to those of pre-menopausal women.
These neurological changes may be responsible for some menopausal symptoms, including hot flashes, mood disruption and a mild, usually temporary decline in memory and cognition.
They also resemble changes in the brain that precede dementia. “Some of the brain regions that are impacted by menopause are also some of the regions impacted by Alzheimer’s disease,” Mosconi said, but the link between the two is not fully understood.
The symptoms of menopause themselves, such as lack of sleep and hot flashes, have been linked to dementia too. A study published last year found that hot flashes were associated with an increased amount of tiny lesions in the brain, which are a sign of declining brain health, said Dr Pauline Maki, a professor of psychiatry and director of the Women’s Mental Health Research Program at the University of Illinois at Chicago and co-author of the study. A more recent study determined that hot flashes during sleep were associated with an increase in blood-based Alzheimer’s biomarkers that serve as early indicators of the disease.
While this research sounds alarming, most women’s brains and cognitive function stabilise after the menopause transition, Maki said.
“Consider how many women go through menopause — every woman, right? And 80 per cent of them will not get dementia,” she said. “We can’t catastrophise this universal transition.”
Beyond that, there are things you can do to bolster your health and cognition in the face of declining estrogen.
Three steps to protect your brain
Several studies have found that up to 40 per cent of dementia cases could be prevented, said Dr Jessica Caldwell, director of the Women’s Alzheimer’s Movement Prevention Center at the Cleveland Clinic in Las Vegas. And a few lifestyle changes in midlife, including quitting smoking, reducing alcohol intake, sleeping better and remaining mentally and socially active, aid in prevention.
But for women in menopause, experts say that three things in particular are likely to have the most impact by addressing both the short-term symptoms as well as the long-term risk of dementia.
Hormone therapy, timed right
For decades, researchers were concerned that the hormone therapy used to treat menopause symptoms was associated with an increased risk of developing dementia in older women. But recent studies, including one published last month that reviewed the findings of over 50 studies, look more closely at the timing of the therapy and suggest a more nuanced picture: hormone therapy that was started around the time when menopausal symptoms began was associated with a reduced risk of Alzheimer’s disease and dementia.
Other studies have found that hormone therapy had no effect on dementia and Alzheimer’s risk, Maki said, but these treatments are effective at addressing hot flashes and night sweats as well as improving quality of life, all of which are “important determinants of brain health”, she said.
Consistent exercise
Physical inactivity presents a greater risk for neurodegenerative diseases in women than in men, Caldwell said. “We know that physical inactivity is a risk factor for dementia. And women throughout their lives, on average, are twice as likely to be physically inactive than men.”
A 2018 study that followed almost 200 middle-aged women for 44 years found that the greater their fitness level at the start of the study, the lower their risk of developing dementia later in life. And Mosconi found that brain scans of physically active middle-aged women had fewer Alzheimer’s biomarkers compared to their sedentary counterparts.
A healthy diet
In recent years, researchers have found that certain diets, like the Mediterranean diet and the fairly similar MIND diet, which prioritise vegetables, fruits, wholegrains, lean proteins and healthy fats, are associated with a reduced risk of dementia in both men and women. The Mediterranean diet in particular seems to be a protective tool, even for women with a genetic risk for Alzheimer’s disease, Mosconi said.
And there may be a specific added benefit of these plant-rich diets for women: preliminary research suggests that certain gut bacteria — which are nourished by a plant-rich diet — might help balance estrogen levels in the body.
Many of these lifestyle changes take time that many middle-aged women feel they don’t have, Caldwell said.
“We are expected by society to put ourselves after everybody else, whether that’s kids, parents or spouses, and we need to keep ourselves on the priority list,” she said. “Because if we don’t do these types of health-maintenance behaviours, we will not have the healthy brain aging we want.”
Written by: Alisha Haridasani Gupta
Illustration by: Sonia Pulido
©2023 THE NEW YORK TIMES
