People who have parents or siblings with dementia have a 72% greater risk of developing dementia themselves—but there are six lifestyle factors that can curb overall dementia risk by about half, according to a new study in Circulation.

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Study details

For the study, researchers looked at health information on 302,239 men and women ages 50 to 73 who had completed a baseline physical examination as part of the U.K. Biobank Study between 2006 and 2010.

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The study participants, who were free of dementia at the start of the study, also completed questionnaires about family history and lifestyle.

For the purpose of analyzing the impact of lifestyle factors on dementia risk, the researchers considered participants to earn one "point" for each of six lifestyle behaviors they said they adhered to, including:

• Eating a healthy diet with less processed meat and refined grains and more fruits and vegetables;
• Completing at least 150 minutes of moderate to vigorous physical activity per week;
• Sleeping between six and nine hours each day;
• Drinking alcohol in moderation;
• Not smoking; and
• Not having obesity, which was defined as having a body mass index of at least 30 kg/m.

The researchers then tracked who developed dementia and who didn't over approximately an eight-year period.

Key findings

According to the researchers, over the course of the study period, 1,698 participants (0.6%) developed dementia.

The researchers found that those with a history of "familial dementia"—defined in the study as those who had a parent or sibling with dementia—had a 72% increased risk of developing the disease compared with those without familial dementia.

However, the researchers also found that adhering to healthy lifestyle behaviors substantially curbed the risk of dementia, whether or not an individual had a history of familial dementia.

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Specifically, the researchers found that people who adhered to all six healthy lifestyle behaviors reduced their risk of dementia by about half when compared with those who followed just two or fewer healthy lifestyle behaviors—an association that held even after controlling for familial dementia and other risk factors, such as age and education level.

Similarly, when compared with those who followed two or fewer healthy lifestyle behaviors, people who adhered to at least three such behaviors had a 30% reduced risk, and people who followed four or five such behaviors had a 42% reduced risk.

Discussion

Angelique Brellenthin, assistant professor of kinesiology at Iowa State University and an author on the study, said the study findings suggest "there may be opportunities for reducing risk by addressing … non-genetic factors," such as a person's diet, physical activity, or smoking status.

Brellenthin also noted that those who adhered to more of the health behaviors at the baseline also reported more familial dementia at baseline.

"For example, there was an 11% prevalence of familiar dementia among those following two or fewer health behaviors, compared to 15% prevalence of familial dementia among those following all six health lifestyle behaviors," Brellenthin said. "And individuals who followed more healthy behaviors were less likely to develop dementia in general."

According to Brellenthin, this correlation may indicate that those who know they're at an increased risk of developing dementia might be proactively taking steps to curb that risk.

Mitchell Elkind, president of the American Heart Association, said it's been known for a long time that "increasing physical activity and decreasing the amount of time spend in sedentary behaviors … can improve one's heart health. Now we're seeing that those same activities can also decrease one's chance of cognitive decline and dementia, and improve brain health."

Elkind added the study results "should be reassuring and inspiring to people to know that following just a few healthy behaviors can delay cognitive decline, prevent dementia, and preserve brain health" (Searing, Washington Post, 5/31; AHA release, 5/20).