A study of seniors finds further evidence that hardened arteries are tied to the development of dementia.

Experts have known for some time that heart health and brain health are linked, but new research suggests that hardened arteries are tied to the brain plaques seen in patients with Alzheimer’s disease.

Researchers scanned the brains of 91 people between the ages of 83 and 91 who did not show signs of dementia. These seniors had been healthy and active throughout their lives.

Half of them had beta amyloid plaques, the telltale sign of Alzheimer’s disease.

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Researchers found that those with brain plaques were also more likely to have high blood pressure and greater arterial stiffness. Those with amyloid plaques and brain lesions had the highest levels of arterial stiffness, meaning that their hearts were working harder to pump blood, putting them at risk for heart attack and stroke. In fact, every unit increase of stiffness in the arteries doubled a person’s likelihood of developing plaques in the brain.

“We feel like what we found is really strong,” lead researcher Tim Hughes of the University of Pittsburgh told Healthline. “We’ve known for a while that vascular and brain health were linked, but our findings may lead to more precise measures of Alzheimer’s risk.”

Beta amyloid plaques are clumps of proteins that accumulate in the brain and interfere with how brain cells communicate. While the specific cause of Alzheimer’s is unknown, beta amyloid plaques are the prime suspect. To locate them, these researchers used a compound that binds to and highlights amyloid plaques in the brain under positron emission tomography (PET) scans.

The study, supported by the National Institutes of Health and the National Institute on Aging, was published today in the journal Neurology.

Calling the study “interesting,” Maria Carrillo, vice president of Medical and Scientific Relations at the Alzheimer’s Association, said, “The study population is small, but nonetheless large enough to have some credibility and make us want to further explore the results. The findings are consistent with thinking in the Alzheimer’s field that heart health and brain health are inexorably linked, but this study takes it one step further by including the presence of beta amyloid in the brain, as well.”

Hardening of the arteries, or atherosclerosis, is a natural part of aging, while Alzheimer’s and other forms of dementia are not.

A 1997 study was one of the first to link dementia and atherosclerosis, stating that people with severely hardened arteries were three times more likely to have dementia.

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Hughes now plans to study adults as young as 50 to measure their levels of atherosclerosis and see when plaques begin to form in the brain. While a lot of Alzheimer’s research is focused on determining how to break up plaques that have formed in the brain, Hughes and other researchers are hoping to prevent their development.

“The reality is that as we get older, our arteries stiffen,” he said. “What we’re trying to get at is, what is healthy brain aging?”

“There’s quite a lot of modifiable risk factors out there, and we’re learning which ones can help prevent Alzheimer’s,” Hughes said.

Experts have known for quite some time that exercise is good not only for the heart, but also for the brain. It can boost brain function and lessen the symptoms of diseases like Alzheimer’s, stroke, and depression.

Exactly how it worked, however, remained elusive until recently.

A new study in the journal Cell Metabolism identified a specific protein released during exercise that promotes brain health. Harvard Medical School researchers say it could be used to develop drugs to guard against neurodegenerative diseases and protect brain function in seniors.

Until those drugs are available, getting regular exercise and challenging your brain are the best ways to stave off mental decline. Eating a diet low in fat and cholesterol has also been shown to reduce a person’s risk of arterial stiffness.

“It’s quite possible that cardiovascular exercise and staying active are going to help you in the long run,” Hughes said.