very day, Alzheimer’s disease forces women to make hard, life-altering choices about their careers, relationships, and finances.
Christell and Shari Anderson are two of them. In 2004, Christell was diagnosed with Alzheimer’s, which slowly stole away her life as she knew it. In 2015, her daughter, Shari, left behind a house, a sales job at a major hotel chain, and a volunteer position with her local chamber of commerce in Shreveport, La., to move to Wichita, Kan., to care for her mother. Christell can no longer speak or walk, and requires round-the-clock care.
Sadly, the Andersons’ situation is not unique. Women make up nearly two-thirds of the more than 5 million Americans with Alzheimer’s disease. A woman in her 60s is now about twice as likely to develop Alzheimer’s as breast cancer during her lifetime. And as described in a Viewpoint article published this week in JAMA Neurology, women shoulder the majority of caregiving for those with dementia. In fact, two and a half times as many women as men reported living full time with a person with dementia.
The prevailing theory for why Alzheimer’s disease disproportionately affects women is that they generally live longer than men. However, mounting evidence suggests that longevity alone may not account for the difference.
The link between differences in sex biology and Alzheimer’s is complex, and likely a product of the interplay between the aging of systems responsible for hormone delivery in the body, hormonal changes over time, and genetic risk for the disease. For example, both human and animal studies suggest that aging-related declines in estrogen, progesterone, testosterone, and other hormones leave brain cells vulnerable to toxic threats, including those from Alzheimer’s.
In May 2015, I had the honor of co-chairing a think tank of scientific experts hosted by the Alzheimer’s Association to map out a research agenda to increase understanding of how Alzheimer’s develops and progresses differently between the sexes. As a result of the meeting, the association — the leading nonprofit funder of Alzheimer’s and dementia research — launched its first-ever Sex and Gender in Alzheimer’s research grants. The effort is providing $2.2 million to nine projects.
As one of the funded researchers, my team is investigating whether women with a known risk gene for Alzheimer’s disease, called APOE-e4, combined with certain sex-specific hormone transitions, incur more substantial brain cell damage than those without this genetic risk. We also will be evaluating whether an investigational therapy we developed can delay or reverse this process.
Other projects funded by the grants include exploring lifestyle interventions that can influence a woman’s risk for developing the disease, such as education, exercise, diet, stress, and sleep. For example, there is strong evidence that formal education across the lifespan, from early life to late life, can boost resilience to cognitive decline and dementia. While disparities in formal education between women and men are declining in the US, they remain substantial among older people currently at highest risk for Alzheimer’s and other dementias. And a growing body of evidence indicates that the cumulative stress of caregiving can increase the risk of developing multiple chronic conditions, including Alzheimer’s.
Only recently has the disproportionate impact of Alzheimer’s and other dementias on women been acknowledged and highlighted. Now we must dig deeper into how the relationship between genetic, hormonal, and lifestyle factors affect the brain over time. Through these efforts, there is an opportunity to better understand the causes and drivers of Alzheimer’s, and which of them are unique to each sex.
Studying and addressing gender differences in disease can pay dividends. Death rates for heart disease dropped by nearly half once it became known that it was a leading cause of death in women. Research showing how women experience heart disease differently from men is helping doctors fine-tune diagnosis, prevention, and treatment. This includes adjusting blood thinner dosage and prescribing low-dose aspirin depending on an individual’s sex, particularly for older women who have already had a heart attack.
Parallel successes in Alzheimer’s could mean fewer stories like the Andersons’. Perhaps a hormone-based therapy or gender-specific lifestyle-based intervention — or a combination of the two — will someday provide the edge needed to prevent the onset of Alzheimer’s or delay dementia symptoms. This could mean not allowing Alzheimer’s to rob you of your independence and the ability to remember your loved ones later in life, or not having to sacrifice your desired path in life — including your job, family, finances, and community interests — for 24/7 caregiving responsibilities.
A sustained commitment to federal funding for Alzheimer’s research is critical to continue the discovery of new approaches and treatment targets. Historically, when we have invested strongly in research — as we have for heart disease, cancer, and HIV/AIDS — effective treatments and prevention strategies have been the result. This is something that all women — and men — should advocate for.
Roberta Diaz Brinton, PhD, is director of the Center for Innovation in Brain Science at the University of Arizona Health Sciences in Tucson.