Taking Care of the Heart in Midlife Can Help to Slow or Prevent Dementia Onset
Midlife is a window of opportunity for protecting heart health—and the benefits may extend to improved brain health in later life.
A new analysis on the lifetime risk of dementia in the U.S. delivered some sobering results: From age 55 to 95, the lifetime risk of developing dementia is 42%, amounting to 1 million cases annually by 2060—almost double the 514,000 cases reported in 2020. Dementia currently affects 6 million Americans.
The study, published on January 13 in Nature Medicine, points to the urgency of addressing the projected steep rise in dementia cases over the coming decades. Researchers analyzed data between 1987 and 2020 from the Atherosclerosis Risk in Communities (ARIC) study, which has tracked nearly 16,000 people for three decades in four communities to investigate risk factors for heart disease and, more recently, the connections between cardiovascular and cognitive health. (The Bloomberg School runs the Washington County, Maryland, component of the study.)
“Something that our society really wrestles with is how to deal with people who need intensive, long-term care in older age,” says Elizabeth Selvin, PhD ’04, MPH, a study co-author, professor in Epidemiology, and director of the Welch Center for Epidemiology and Clinical Research. However, researchers say the message of the study is not one of “doom and gloom.” Rather, the findings present an opportunity to address dementia risk factors and take steps in middle age to prevent or slow the onset of dementia later in life.
Selvin and Michael Fang, PhD, MHS, assistant professor in Epidemiology and lead author of the study, discuss why taking care of the heart protects the brain, addressing dementia risk factors in midlife, and positive takeaways from the new study.
What is the main message of the study?
MF: The message isn’t doom and gloom and that everyone's just going to get dementia at some point. I am hoping that it raises awareness that if you live long enough, your risk increases—and this risk may be a lot higher than we previously thought. But there are things that you can do on an individual level to reduce the burden of dementia, including trying to optimize your cardiovascular health (avoiding diabetes, hypertension, smoking). And for people who are in positions of policymaking, developing broad strategies and interventions that improve cardiovascular health can also help on a population level. The future that we projected in the paper doesn't necessarily have to be the future that we eventually see if we start implementing strategic policies and taking action now.
ES: A positive message is that focusing on a healthy lifestyle and improving heart health will have important benefits for your brain health and preventing dementia.
Research has suggested that it’s possible to take protective steps in middle age to delay or prevent dementia. Why is this a time of life to act?
ES: Much of our work in ARIC has been focused on midlife risk factors for late life dementia. We’ve shown very strong associations with midlife risk factors: Diabetes, hypertension, and smoking are the big ones. It turns out there's more bang for your buck if you focus on the midlife risk factors. If you prevent diabetes in middle age, if you improve diabetes control, if you prevent hypertension, if you aggressively manage blood pressure, this has long-term benefits that can delay or prevent dementia in later life.
There’s some evidence that better risk-factor management in later life can also help, but the real benefits are in midlife. That's been one of the important discoveries and messages from the work in ARIC. ARIC is unique because we have detailed information in midlife and more than three decades of follow-up for dementia and other outcomes.
If you prevent diabetes in middle age, if you improve diabetes control, if you prevent hypertension, if you aggressively manage blood pressure, this has long-term benefits that can delay or prevent dementia in later life.
How might the brain be affected generally if someone has dementia risk factors in middle age?
MF: We start seeing different regions of the brain show signs of damage earlier on. When you have diabetes there is evidence that your brain starts undergoing neurodegeneration at a much faster rate than if you don’t have this condition. We've also done studies in ARIC where we've taken images of people's brains, with diabetes and without diabetes, and shown that people with diabetes have smaller brain volume. So there's differences in brain sizes. These studies suggest that when you have cardiovascular risk factors like diabetes, you start experiencing damage more rapidly, so I think that speaks to the importance of earlier prevention.
What does prevention look like in terms of risk factors like diabetes, high blood pressure, and smoking?
ES: It’s the stuff we know, but I am not sure people know that this will also prevent dementia. Maintaining a healthy weight, which is essential to preventing type 2 diabetes. Being active. Eating a healthy diet with lots of fruits and vegetables. Not smoking, or quitting smoking if you’re a current smoker.
A lot of people are worried about genetic risk. One important genetic risk factor is having an APOE4 allele, but we've shown that a diagnosis of diabetes in midlife has a similar effect as having one APOE4 allele. So some ARIC study findings have shown that by focusing on vascular risk factors in midlife, you can help mitigate genetic risk.
Maintaining hearing is also important for maintaining cognitive function. A study that involved ARIC participants and led by our colleague Frank Lin, MD, PhD, director of the Cochlear Center for Hearing and Public Health, demonstrated that a hearing aid intervention in older adults at high risk for dementia was associated with less cognitive decline over three years than those without hearing aids. [Ed. note: The Hearing Number app, recently launched by the Bloomberg School for iOS and Android, allows users to self-test their hearing with a widely used clinical measure. In this way, people can track their hearing over time and adopt technologies to improve hearing when indicated.]
Do you think it’s widely understood that middle age is a key period to take preventive actions against cognitive decline and dementia?
MF: That was part of the motivation of doing this whole lifetime risk estimate. The original use of lifetime risk was actually in the breast cancer space to encourage early screening and engagement in prevention. The idea was when you're young, you don't really think about the risk of breast cancer, but if you show the risk over the entirety of your lifespan, then it raises awareness that at some point this is something you should be thinking about.
In that same sense, dementia is something we don't typically think about until we're much older. But if someone shows you a curve that if you live to your 70s, 80s, and 90s, this is something that you may have to think about, that puts it into perspective.
Our assumption in those projections is that people's risks will remain the same. We took the risk in the people in our study, and applied that uniformly to the next 40 years. But that risk doesn't necessarily have to stay static. We can do a better job in terms of prevention to reduce the risk in the population, and that theoretically will in turn reduce and lower some of that curve, and some of those individuals may not end up developing dementia.
Jackie Powder is the associate editor of Hopkins Bloomberg Public Health magazine.
