Barrow study examines geographic ties between dementia and cardiometabolic disease in the U.S.

A “substantial number” of dementia cases in the U.S. could be eliminated by reducing cardiometabolic conditions such as heart attack, stroke and diabetes, according to a new study from Barrow Neurological Institute at Dignity Health St. Joseph's Hospital and Medical Center in Phoenix.

The study, which was recently published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, probed regional data and found the strongest tie between dementia and cardiometabolic conditions in the South.

The study comes at a time when 6.7 million Americans aged 65 and older are living with Alzheimer’s disease, according to the Alzheimer’s Association, and the number is expected to rise to 13 million by 2050.

While those numbers are alarming, the study’s authors argue that the rise of dementia cases could be stemmed by controlling cardiometabolic diseases.

Barrow researchers defined cardiometabolic diseases (CMDs) as diabetes, chronic heart failure, atrial fibrillation, ischemic heart disease, acute myocardial infarction, stroke/transient ischemic attack, hypertension, and hyperlipidemia. They found that 37 percent of U.S. dementia cases could be linked to one of those diseases, with hypertension (9.6%), ischemic heart disease (6.7%), and chronic heart failure (5.7%) the leading causes.

“A substantial number of dementia cases could be eliminated by mitigating modifiable cardiometabolic risk factors, especially in U.S. counties with a high risk of dementia attributed to these risk factors,” says Brad Racette, MD, Chair of Neurology at Barrow Neurological Institute.

Researchers estimate that eliminating eight CMD risk factors from the population would reduce incident dementia cases among Medicare beneficiaries nationally by 37 percent. “More realistically, a 15 percent proportional reduction in these risk factors would reduce incident dementia cases in the population by an estimated 6.3 percent,” Dr. Racette says.

Other studies have examined the connection between CMDs and dementia. The Barrow study broke ground by using novel Geographic Information Systems techniques and the geospatial patterns of the combined effect of CMDs on dementia to identify spatial risk clusters of dementia due to CMDs.

Researchers built their study on claims data from Medicare, the only nationwide, population-based health care program in the U.S. To be eligible for this study, individuals had to be aged 67 to 110 years, enrolled in Medicare Part A and/or B without Part C

coverage, and a U.S. resident of one of the 50 states or District of Columbia.There were 20,789,037 beneficiaries in the U.S. Medicare population who were included in this study - 756,321 (3.6%) dementia cases and 20,032,716 (96.4%) controls. The study revealed the strongest link between CMDs and dementia in the South.

“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,” Dr. Racette says.

By contrast, CMDs attributed far less to dementia risk in the Pacific Northwest, Great Plains, and the Rocky Mountains compared to the rest of the U.S.

Researchers acknowledged some limitations to the study. Medicare is national health insurance for those 65 years and older, but they had to exclude those with Medicare Advantage plans from analyses since those plans do not report detailed claims to CMS.

The study was supported by the Barrow Neurological Foundation, the Kemper and Ethel Marley Foundation, and the Moreno Family.