Of the estimated 5.7 million Americans who are living with Alzheimer’s disease, about two-thirds are women. The threat of the disease is significant: Women in their sixties are about twice as likely to develop Alzheimer’s over the rest of their lives as they are to develop breast cancer. But, as Lisa Mosconi, director of the Brain Health Initiative, writes in her recently released book, “The XX Brain: The Groundbreaking Science Empowering Women to Maximize Cognitive Health and Prevent Alzheimer’s Disease,” while “breast cancer is clearly identified as a women’s health issue, Alzheimer’s is not.” In the following excerpt from the book, which hit shelves March 10, Mosconi talks about some of the myths associated with Alzheimer’s — and why the differences between men and women’s brains matter.
In twenty years of research, some of the most surprising, important, and neglected findings I’ve come across are about the real ways the female brain works. However, as long as a woman’s brain lies far above and beyond her “bikini line,” these vital differences often continue to go unaddressed. Case in point: Alzheimer’s is a huge threat to women’s health, and nobody talks about it. If there was a meteor that was going to hit several million people in thirty years, we’d presumably set aside resources and brainpower to stop it. Instead, most women are not even aware of the problem. The media doesn’t report on it. Doctors aren’t trained to address it.
So before we can talk about the reality of what’s ahead for each woman, and for women as a whole, let’s look at some enduring myths that have kept us, as a society, from recognizing, addressing, and preventing the unique risks to women’s brain health.
This is a moment when the notion of bias has risen to the forefront of culture, and in many cases it is very real and necessary to confront. From a health-care perspective, there are a few biases that deserve large-scale and immediate attention, because like all preconceptions, their consequences can be widespread and disastrous.
The double bias women suffer from is by no means the only misinformed perspective around aging. The field of Alzheimer’s research, for one, suffers from a very similar problem. In fact, the disease is generally understood as the inevitable outcome of unlucky genes, aging, or both. You can just imagine how difficult it’s been to gain a balanced perspective on how real Alzheimer’s risk is for women—and just how important it is to do so.
Alzheimer’s is the most extreme manifestation of a suffering brain, and ultimately, by understanding what leads to Alzheimer’s, we will also understand what leads away from it. If we stay with the comparison of Alzheimer’s to a stock market crash, the same way that economists who study stock market crashes also study what makes a healthy economy, so scientists who study Alzheimer’s are actually learning what makes a healthy, resilient, long-lived brain.
While some of these discoveries are indeed specific to Alzheimer’s, many of the most important ones have a far broader reach. They provide evidence for an uncomfortable but unavoidable truth: there are specific factors that make women especially vulnerable to a number of conditions that negatively impact overall brain health. Additionally, we now understand that even though both genders can experience cognitive changes, men and women tend to do so for different reasons. Sex differences in brain aging and dementia are only just being acknowledged, but the consequences of these findings are already changing the way we fight disease.
There’s always been a persistent sense that illnesses that affect the brain are due to genetics, and that if your mother or father had a specific disease, chances are you’ll get it, too. But a slew of new research using next generation medical imaging and genomic sequencing has completely upended our understanding of the role of aging and genetics in the development of many illnesses, Alzheimer’s first and foremost.
The truth is, while some people do indeed develop diseases like Alzheimer’s due to genetic mutations in their DNA, this typically happens to no more than 1 to 2 percent of the population. This is a much lower number than previously thought, and clearly contradicts the story that genes are destiny in this regard. For most people, risk has much less to do with “bad genes” and much more to do with the combination of our unique genetic makeup, our medical health, the environment in which we live, and all the choices we make on a daily basis.
This is not to say that our genes are not important. Our DNA is involved in every aspect of our lives, including making us women. However, from a medical perspective, it turns out that our genes are not as deterministic as we previously thought.
Keep this fact close to heart; it is the game changer.
But winning and losing have less to do with those cards than with the way you play the game: your environment, lifestyle, medical history, and, especially for women, hormonal health. Study after study shows that these factors act synergistically as powerful epigenetic forces that modify the way our DNA networks play out, by switching select genes on and off. While this doesn’t change the structure of our DNA, it does change the expression of our genes throughout our lives, thereby influencing our chances of developing or not developing any given disease. As a result, we have come to appreciate that the underlying causes of most forms of cognitive decline, although sometimes genetic, are just as often linked to these other factors that are within our control.
From a scientist’s perspective, it’s important to remind everyone that we all once believed that conditions like depression, stroke, and even cancer were essentially unavoidable genetic outcomes. Instead, they have all turned out to result in great part from the interactions of genetic susceptibility and a large number of medical and environmental factors. Medical conditions known to affect brain health, such as heart disease, obesity, and diabetes, are also much more likely to arise from lifestyle factors than from genetic mutations. To give you a better sense of the scale of magnitude, it was estimated that 80 percent of all cases of cardiovascular disease and as many as 90 percent of all cases of type 2 diabetes in recent years were caused by nothing more than an unhealthy lifestyle. Consequently, they might have been prevented by paying more attention to things like dietary choices, weight control, and physical activity.
As it turns out, this is also the case for Alzheimer’s. Recent population-based studies estimate that at a minimum, one-third of all Alzheimer’s cases could be prevented by attending to key medical and lifestyle shifts. These shifts include a different approach to diet and exercise, conscientious intellectual and social engagement, stress reduction, better sleep, balancing hormones, avoiding smoking and toxin exposure, and management of cardiovascular health, as well as those factors leading to obesity and diabetes, to name a few. These practices work in powerful harmony to keep dementia at bay.
For many years, the collective mind-set has been that, since women tend to live longer than men, their longer life spans meant that they would simply “have more time” to exhibit Alzheimer’s in higher numbers. In other words, it was a question not worth studying. As a scientist, and a general advocate for common sense, I approached this issue with a very simple question.
It turns out that this fabled longevity gender gap is in fact closing. Men are catching up. For example, life expectancy in the United States is currently eighty-two years for females and a little over seventy-seven for males, a difference of less than five years. In England, the difference is anticipated to be less than two years by 2030. In many other countries, the “big” difference in life spans isn’t that big after all, and it’s actually heading in the direction of no difference.
Interestingly, research shows that behavior and technology, rather than genetics, are the main reasons for the rapidly narrowing gender gap. At the beginning of the twentieth century, technological and medical progress did indeed lead to a gender disparity in mortality rates. As infectious disease prevention, improved medical technologies, better diets, and other positive health behaviors were adopted by people born during the early 1900s, death rates plummeted for both women and men. However, while women took full advantage of these improvements, men fell victim to the parallel rise of aptly called “man-made diseases.” These include mostly alcoholism, smoking, gun violence, and road accidents, which tend to be more typically “male” health risks. Even the higher incidence of heart disease in men has been largely attributed to smoking, as well as to a poor diet. In other words, the consequences of male behaviors led to the belief that women had some biological advantage in the longevity department.
Rather, today’s women are at risk of replicating the history of yesterday’s men by taking on behaviors and stresses that were formerly considered a man’s prerogative: smoking, drinking, and climbing corporate ladders. The impetus to “lean in” as female entrepreneurs working a hundred hours a week? Commonplace. Women raising small children while holding full-time jobs? Quite the norm. Women working not one but two jobs to support the family? Prevalent now for decades. A female president or prime minister? In some parts of the world, already the case. Perhaps related to these increasing demands, women over fifty now bear the same risk of heart disease as men. Mortality from lung cancer has almost tripled in women in the past two decades. The prevalence of obesity, anxiety, and depression has also increased significantly more for women than for men. Ditto for the risk of infections and a variety of hormonal conditions, from thyroid disease to infertility.
And while all this “progress” has been in process, men have learned to take better care of themselves, leading to the reduction in male mortality and the narrowing gender gap in life expectancy. When it comes to women’s self-care, the opposite case is true.
In the broadest possible terms, men are being less injurious to their own health, and women have become more so.
What all this points to is that women’s changing roles in society, and all the unhealthy behaviors, stresses, and struggles that have come from and with that, have been silently affecting not only our hearts, hormones, and waistlines—but our brains, too. It is in fact our brains that have been suffering to the point of precipitating our chances of developing a neurological disorder like Alzheimer’s. One can just imagine what these same changes have done to our cognitive health at large, further highlighting the importance of our lifestyle and medical health above and beyond that of our age or genes.
Which brings us back to where we began: Can a couple of years’ difference fully account for the fact that two out of every three Alzheimer’s patients are women? Having taken a closer look, I think it seems unlikely. Although age certainly plays a role, statistical models that account for gender-dependent mortality rates broadly show the same 2:1 ratio at any age. In plain English, women with Alzheimer’s outnumber men with Alzheimer’s two to one regardless of their age, age at death, and differences in life span. The brain imaging studies discussed in chapter 1 lend further support to these findings by revealing that the problem isn’t just that women live longer—it’s that they seem to start getting the disease earlier. Specifically, around menopause. A woman as young as forty-five already has a one in five chance of developing Alzheimer’s.
Thanks to the latest research, we can take advantage of the newly discovered window of opportunity to identify, address, and act upon our risk factors before symptoms have a chance to emerge.
Spurred by the new wave of data showing that Alzheimer’s prevention is indeed feasible, it is becoming more common for medical providers to deliver direct clinical care to improve brain health, thereby reducing Alzheimer’s risk, with a number of clinics focusing on both risk assessment and early intervention. Recent clinical trials have also provided persuasive evidence that targeted risk-reduction interventions can help us maintain cognitive function in old age. With the current failure of Alzheimer’s drugs as a viable option, these findings offer us the much-needed alternative we’ve been striving for, empowering even the greatest skeptic not only with renewed hope, but also with the motivation to do what’s necessary to safeguard ourselves and thrive throughout every stage of our lives.
This is particularly good news for women, as there is compelling evidence that women’s brains can really benefit from specific medical and lifestyle practices, giving us the ability to reset the scales in our favor. These interventions are both safer and better tolerated than medications, yielding just as effective, and sometimes even better, results. The key is to tailor treatment toward each patient’s unique risks and needs.
Reprinted from “The XX Brain: The Groundbreaking Science Empowering Women to Maximize Cognitive Health and Prevent Alzheimer’s Disease” by arrangement with Avery, an imprint of Penguin Publishing Group, a division of Penguin Random House LLC. Copyright © 2020, Lisa Mosconi, PhD.