Study finds geographic link between dementia and cardiometabolic disease

As the number of older adults in the U.S. continues to climb, dementia is becoming one of the nation’s most pressing public health issues. Affecting memory, thinking, and behavior, dementia is not a single disease but rather a group of symptoms caused by different brain disorders. It is now the seventh leading cause of death worldwide and a major source of disability and dependence among aging populations.

A new study from researchers at Barrow Neurological Institute highlights a key insight that could change how the U.S. approaches dementia prevention. It shows that many dementia cases could be avoided by reducing common health problems tied to the heart, blood vessels, and metabolism—conditions that are preventable or manageable with better health care and lifestyle choices.

This study, published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, used geographic information systems (GIS) to map where dementia risk overlaps with high rates of certain health conditions. These include diabetes, high blood pressure, stroke, heart disease, and high cholesterol—collectively known as cardiometabolic diseases (CMDs).

Using GIS, researchers examined claims data from nearly 21 million Americans enrolled in Medicare between ages 67 and 110. Out of those, over 750,000 had been diagnosed with dementia. The data came from across all 50 states and Washington, D.C., giving the researchers a clear view of how regional patterns of health can shape dementia risk.

What they found was striking. The highest concentration of dementia cases linked to CMDs appeared in the Southern United States. This region has long faced higher rates of obesity, poor nutrition, and limited access to health care. These factors help explain why the South stood out so sharply in the study.

“Regional variation in dementia burden can be explained partially by the disproportionate concentration of obesity, lack of physical activity, and unhealthy diet among those living in Southern states,” said Dr. Brad Racette, Chair of Neurology at Barrow Neurological Institute and lead author of the study.

The study’s findings suggest that a large share of dementia cases are not only tied to aging but are deeply connected to other diseases. CMDs played a role in 37 percent of dementia cases nationally.

Among the most influential risk factors were high blood pressure, which contributed to 9.6 percent of dementia cases; ischemic heart disease, responsible for 6.7 percent; and chronic heart failure, which accounted for 5.7 percent. These diseases often share roots in poor diet, lack of exercise, smoking, and long-term stress—factors that could be improved through public health measures and better individual care.

“A substantial number of dementia cases could be eliminated by mitigating modifiable cardiometabolic risk factors,” Dr. Racette emphasized, “especially in U.S. counties with a high risk of dementia attributed to these risk factors.”

While eliminating all CMDs would be ideal, researchers modeled what might happen with more realistic improvements. They found that even a 15 percent reduction in these risk factors could lower dementia rates among older adults by 6.3 percent. That modest drop would still mean thousands of people spared the challenges of memory loss and mental decline each year.

The reasons behind dementia are complex. It doesn’t stem from a single cause. Scientists have identified both internal and external risk factors that accumulate over time. These range from genetics and age to environment and behavior.

Earlier studies have shown that people with fewer social connections, especially in early and midlife, face higher dementia risk. Lack of physical activity, poor diet, smoking, and air pollution also add to the danger. On their own, each factor may seem small. Together, however, they create a powerful wave that builds across decades.

While many studies have looked at individual risk factors, this new research stands out by examining how several of them interact across different regions. That big-picture view helps public health leaders target areas where interventions are most needed.

The Southern U.S. didn’t just have the highest CMD-related dementia rates—it also had some of the strongest overlaps between health conditions and geography. Areas with the greatest CMD-related dementia burdens tended to be those where high rates of smoking, poor diets, and limited exercise were already common.

This matches findings from past studies, which showed that Southern residents tend to have more chronic illnesses and lower access to preventive care. These conditions don’t just increase dementia risk; they also shorten lifespan and lower quality of life overall.

By contrast, regions such as the Pacific Northwest, the Great Plains, and the Rocky Mountains showed much lower connections between CMDs and dementia. These areas generally have lower obesity rates, higher physical activity, and better access to primary health care.

The importance of the Barrow study lies not just in what it discovered, but in how it could guide future action. Understanding where and why dementia risk is rising can help governments and communities focus their health campaigns.

If health officials know which counties have the highest rates of CMD-related dementia, they can roll out better education, screenings, and preventive programs in those regions. That might include nutrition assistance, smoking cessation programs, or improved access to primary care clinics.

This approach could reduce not only dementia, but also other chronic illnesses that cost billions in health care spending each year. And by focusing on the areas with the highest risk, public health programs could use their resources more efficiently.

The study focused on older Americans enrolled in traditional Medicare. People who had Medicare Advantage plans were not included because those plans do not report the same level of detailed claims data.

Despite this limitation, the study still analyzed nearly 21 million people, offering a robust look at nationwide trends. Researchers were supported by the Barrow Neurological Foundation, the Kemper and Ethel Marley Foundation, and the Moreno Family.

Even though dementia can’t be fully prevented in every case, studies like this show that it is far from inevitable. With smarter planning, better care, and targeted efforts, the burden of this growing disease could be eased—for patients, families, and the health care system.

Note: The article above provided above by The Brighter Side of News.

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