Alzheimer’s prevention may be less about new drugs, more about income, zip code and education
That your risk of Alzheimer’s disease depends on your salary, what you ate as a child, or the block where you live may seem implausible. But researchers are discovering that social determinants of health (SDOH) play an outsized role in Alzheimer’s disease and related dementias, possibly more than age, and new strategies are emerging for how to address these factors.
At the 2022 Alzheimer’s Association International Conference, a series of presentations offered evidence that a string of socioeconomic factors—such as employment status, social support networks, education and home ownership—significantly affected dementia risk, even when adjusting data for genetic risk. What’s more, memory declined more rapidly in people who earned lower wages and slower in people who had parents of higher socioeconomic status.
In 2020, a first-of-its kind study in JAMA linked Alzheimer’s incidence to “neighborhood disadvantage,” which is based on SDOH indicators. Through autopsies, researchers analyzed brain tissue markers related to Alzheimer’s and found an association with these indicators. In 2022, Ryan Powell, the lead author of that study, published further findings that neighborhood disadvantage was connected with having more neurofibrillary tangles and amyloid plaques, the main pathological features of Alzheimer's disease.
As of yet, little is known about the biological processes behind this, says Powell, director of data science at the Center for Health Disparities Research at the University of Wisconsin School of Medicine and Public Health. “We know the association but not the direct causal pathway.”
The corroborative findings keep coming. In a Nature study published a few months after Powell’s study, every social determinant investigated affected Alzheimer’s risk except for marital status. The links were highest for income, education, and occupational status.
Clinical trials on new Alzheimer’s medications get all the headlines but preventing dementia through policy and public health interventions should not be underestimated.
The potential for prevention is significant. One in three older adults dies with Alzheimer's or another dementia—more than breast and prostate cancers combined. Further, a 2020 report from the Lancet Commission determined that about 40 percent of dementia cases could theoretically be prevented or delayed by managing the risk factors that people can modify.
Take inactivity. Older adults who took 9,800 steps daily were half as likely to develop dementia over the next 7 years, in a 2022 JAMA study. Hearing loss, another risk factor that can be managed, accounts for about 9 percent of dementia cases.
Clinical trials on new Alzheimer’s medications get all the headlines but preventing dementia through policy and public health interventions should not be underestimated. Simply slowing the course of Alzheimer’s or delaying its onset by five years would cut the incidence in half, according to the Global Council on Brain Health.
Minorities Hit the Hardest
The World Health Organization defines SDOH as “conditions in which people are born, work, live, and age, and the wider set of forces and systems shaping the conditions of daily life.”
Anyone who exists on processed food, smokes cigarettes, or skimps on sleep has heightened risks for dementia. But minority groups get hit harder. Older Black Americans are twice as likely to have Alzheimer’s or another form of dementia as white Americans; older Hispanics are about one and a half times more likely.
This is due in part to higher rates of diabetes, obesity, and high blood pressure within these communities. These diseases are linked to Alzheimer’s, and SDOH factors multiply the risks. Blacks and Hispanics earn less income on average than white people. This means they are more likely to live in neighborhoods with limited access to healthy food, medical care, and good schools, and suffer greater exposure to noise (which impairs hearing) and air pollution—additional risk factors for dementia.
Related Reading: The Toxic Effects of Noise and What We're Not Doing About it
Plus, when Black people are diagnosed with dementia, their cognitive impairment and neuropsychiatric symptom are more advanced than in white patients. Why? Some African-Americans delay seeing a doctor because of perceived discrimination and a sense they will not be heard, says Carl V. Hill, chief diversity, equity, and inclusion officer at the Alzheimer’s Association.
Misinformation about dementia is another issue in Black communities. The thinking is that Alzheimer’s is genetic or age-related, not realizing that diet and physical activity can improve brain health, Hill says.
African Americans are severely underrepresented in clinical trials for Alzheimer’s, too. So, researchers miss the opportunity to learn more about health disparities. “It’s a bioethical issue,” Hill says. “The people most likely to have Alzheimer’s aren’t included in the trials.”
The Cure: Systemic Change
People think of lifestyle as a choice but there are limitations, says Muniza Anum Majoka, a geriatric psychiatrist and assistant professor of psychiatry at Yale University, who published an overview of SDOH factors that impact dementia. “For a lot of people, those choices [to improve brain health] are not available,” she says. If you don’t live in a safe neighborhood, for example, walking for exercise is not an option.
Hill wants to see the focus of prevention shift from individual behavior change to ensuring everyone has access to the same resources. Advice about healthy eating only goes so far if someone lives in a food desert. Systemic change also means increasing the number of minority physicians and recruiting minorities in clinical drug trials so studies will be relevant to these communities, Hill says.
Based on SDOH impact research, raising education levels has the most potential to prevent dementia. One theory is that highly educated people have a greater brain reserve that enables them to tolerate pathological changes in the brain, thus delaying dementia, says Majoka. Being curious, learning new things and problem-solving also contribute to brain health, she adds. Plus, having more education may be associated with higher socioeconomic status, more access to accurate information and healthier lifestyle choices.
New Strategies
The chasm between what researchers know about brain health and how the knowledge is being applied is huge. “There’s an explosion of interest in this area. We’re just in the first steps,” says Powell. One day, he predicts that physicians will manage Alzheimer’s through precision medicine customized to the patient’s specific risk factors and needs.
Raina Croff, assistant professor of neurology at Oregon Health & Science University School of Medicine, created the SHARP (Sharing History through Active Reminiscence and Photo-imagery) walking program to forestall memory loss in African Americans with mild cognitive impairment or early dementia.
Participants and their caregivers walk in historically black neighborhoods three times a week over six months. A smart tablet provides information about “Memory Markers” they pass, such as the route of a civil rights march. People celebrate their community and culture while “brain health is running in the background,” Croff says.
Photos and memory prompts engage participants in the SHARP program.
OHSU/Kristyna Wentz-Graff
The project began in 2015 as a pilot study in Croff’s hometown of Portland, Ore., expanded to Seattle, and will soon start in Oakland, Calif. “Walking is good for slowing [brain] decline,” she says. A post-study assessment of 40 participants in 2017 showed that half had higher cognitive scores after the program; 78 percent had lower blood pressure; and 44 percent lost weight. Those with mild cognitive impairment showed the most gains. The walkers also reported improved mood and energy along with increased involvement in other activities.
It’s never too late to reap the benefits of working your brain and being socially engaged, Majoka says.
In Milwaukee, the Wisconsin Alzheimer’s Institute launched the The Amazing Grace Chorus® to stave off cognitive decline in seniors. People in early stages of Alzheimer’s practice and perform six concerts each year. The activity provides opportunities for social engagement, mental stimulation, and a support network. Among the benefits, 55 percent reported better communication at home and nearly half of participants said they got involved with more activities after participating in the chorus.
Private companies are offering intervention services to healthcare providers and insurers to manage SDOH, too. One such service, MyHello, makes calls to at-risk people to assess their needs—be it food, transportation or simply a friendly voice. Having a social support network is critical for seniors, says Majoka, noting there was a steep decline in cognitive function among isolated elders during Covid lockdowns.
About 1 in 9 Americans age 65 or older live with Alzheimer’s today. With a surge in people with the disease predicted, public health professionals have to think more broadly about resource targets and effective intervention points, Powell says.
Beyond breakthrough pills, that is. Like Dorothy in Kansas discovering happiness was always in her own backyard, we are beginning to learn that preventing Alzheimer’s is in our reach if only we recognized it.
Twice a day, morning and night, I use a neti pot to send a warm saltwater solution coursing through one nostril and out the other to flush out debris and pathogens. I started many years ago because of sinus congestion and infections and it has greatly reduced those problems. Along with vaccination when it became available, it seems to have helped with protecting me from developing Covid-19 symptoms despite being of an age and weight that puts me squarely at risk.
Now that supposition of protection has been backed up with evidence from a solidly designed randomized clinical trial. It found that irrigating your sinuses twice a day with a simple saltwater solution can lead to an 8.5-fold reduction in hospitalization from Covid-19. The study is another example of recent research that points to easy and inexpensive ways to help protect yourself and help control the epidemic.
Amy Baxter, the physician researcher behind the study at Augusta University, Medical College of Georgia, began the study in 2020, before a vaccine or monoclonal antibodies became available to counter the virus. She wanted to be able to offer another line of defense for people with limited access to healthcare.
The nasal cavity is the front door that the SARS-CoV-2 virus typically uses to enter the body, latching on to the ACE2 receptors on cells lining those tissue compartments to establish infection. Once the virus replicates here, infection spreads into the lungs and often other parts of the body, including the brain and gut. Some studies have shown that a mouthwash could reduce the viral load, but any effect on disease progression was less clear. Baxter reasoned that reducing the amount of virus in the nose might give the immune system a better chance to react and control that growth before it got out of hand.
She decided to test this approach in patients who had just tested positive for Covid-19, were over 55 years of age, and often had other risk factors for developing serious symptoms. It was the quickest and easiest way to get results. A traditional prevention study would have required many more volunteers, taken a longer period of follow up, and cost money she did not have.
The trial enrolled 79 participants within 24 hours of testing positive for Covid-19, and they agreed to follow the regimen of twice daily nasal irrigation. They were followed for 28 days. One patient was hospitalized; a 1.27% rate compared with 11% in a national sample control group of similar age people who tested positive for Covid-19. Patients who strictly adhered to nasal irrigation had fewer, shorter and less severe symptoms than people in the study who missed some of their saline rinses.
Baxter initially made the results of her clinical trial available as a preprint in the summer of 2021 and was dismayed when many of the comments were from anti-vaxxers who argued this was a reason why you did not need to get vaccinated. That was not her intent.
There are several mechanisms that explain why warm saltwater is so effective. First and most obvious is the physical force of the water that sweeps away debris just as a rainstorm sends trash into a street gutter and down a storm drain. It also lubricates the cilia, small hair-like structures whose job it is to move detritus away from cells for expulsion. Cilia are rich in ACE2 receptors and keeping them moving makes it harder for the virus to latch on to the receptors.
It turns out the saline has a direct effect on the virus itself. SARS-CoV-2 becomes activated when an enzyme called furin snips off part of its molecular structure, which allows the virus to grab on to the ACE2 receptor, but saline inhibits this process. Once inside a cell the virus replicates best in a low salt environment, but nasal cells absorb salt from the irrigation, which further slows viral replication, says Baxter.
Finally, “salt improves the jellification of liquid, it makes better and stickier mucus so that you can get those virus out,” she explains, lamenting, “Nobody cares about snot. I do now.”
She initially made the results of her clinical trial available as a preprint in the summer of 2021 and was dismayed when many of the comments were from anti-vaxxers who argued this was a reason why you did not need to get vaccinated. That was not her intent. Two journals rejected the paper, and Baxter believes getting caught up in the polarizing politics of Covid-19 was an important part of the reason why. She says that editors “didn't want to be associated with something that was being used by anti-vaxxers.” She strongly supports vaccination but realizes that additional and alternative approaches also are needed.
Premeasured packets of saline are inexpensive and can be purchased at any drug store. They are safe to use several times a day. Say you’re vaccinated but were in a situation where you fear you might have been exposed to SARS-CoV-2; an extra irrigation will clear out your sinuses and may reduce the risk of that possible exposure.
Baxter plans no further study in this area. She is returning to her primary research focus, which is pain control and reducing opioid use, but she hopes that others will expand on what she had done.
Podcast: The Friday Five Weekly Roundup in Health Research
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
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Here are the promising studies covered in this week's Friday Five:
- A pill to prevent lung cancer?
- Ancient wisdom about Neti pots could pay off for Covid
- Breakthrough for precision medicine and obesity
- How to refreeze the north and south poles
- The connection between taking multivitamin pills and brain health