Taking three steps to protect one's heart health in middle age could add more than a decade of dementia-free years onto one's life, a new study suggests.

The research, published Aug. 5 in Neurology Open Access, found that not smoking, maintaining healthy blood pressure and avoiding diabetes between ages 48 and 68 leads to, on average, nearly 13 additional years of life without dementia.

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"Our findings argue that people need to actively avert these factors in midlife as a strategy for preserving brain health for more than a decade," the study's senior investigator, Dr. Josef Coresh, said in a news release.

More than 40% of the U.S. population is at risk of developing dementia after age 55, according to previous research from NYU Langone Health. Blood tests are becoming available to try to identify dementia and Alzheimer's disease risk before symptoms set in, but the tests are not foolproof. And there is no cure for dementia, only medications and lifestyle changes that may help reduce or delay symptoms.

For the latest study, researchers analyzed data from 12,409 people who participated in long-term study that followed them for more than two decades. When the study began in the early 1990s, the participants were 56, on average, and dementia free.

More than 3,000 participants developed dementia, and more than 5,000 died without ever developing dementia. On average, people who had none of the risk factors lived nearly 13 years longer without dementia than people who smoked, had high blood pressure and had diabetes.

Among people who had these risk factors, women lived dementia free longer than men, and white people lived longer without dementia than Black people.

"These results suggest that vascular risk reduction may benefit all groups, but that certain populations, such as Black adults, may especially benefit from targeted prevention efforts," Coresh said. "Hopefully, these results will encourage people to stop smoking and watch their vascular health closely from age 48 on."

The findings were limited by the fact that researchers measured the risk factors only once, at midlife. Also, the study did not prove that not smoking, maintaining healthy blood pressure and remaining free of diabetes directly prevented or delayed dementia. Instead, the findings showed an association between avoiding these vascular risk factors in middle age and more years dementia free.