Individuals at increased risk for dementia because of family history can reduce that risk by adopting healthy lifestyle behaviors, data from more than 300,000 adults aged 50-73 years suggest.
Dr. Angelique Brellenthin
Having a parent or sibling with dementia can increase a person’s risk of developing dementia themselves by nearly 75%, compared with someone with no first-degree family history of dementia, according to Angelique Brellenthin, PhD, of Iowa State University, Ames, and colleagues.
In a study presented at the Epidemiology and Prevention/Lifestyle and Cardiometabolic Health meeting sponsored by the American Heart Association, the researchers reviewed information for 302,239 men and women who were enrolled in the U.K. Biobank, a population-based study of more than 500,000 individuals in the United Kingdom, between 2006 and 2010.
The study participants had no evidence of dementia at baseline, and completed questionnaires about family history and lifestyle. The questions included details about six healthy lifestyle behaviors: eating a healthy diet, engaging in at least 150 minutes of moderate to vigorous physical activity per week, sleeping 6-9 hours each night, drinking alcohol in moderation, not smoking, and maintaining a body mass index below the obese level (less than 30 kg/m2).
The researchers identified 1,698 participants (0.6%) who developed dementia over an average follow-up period of 8 years. Those with a family history (first-degree relative) of dementia had a 70% increased risk of dementia, compared with those who had no such family history.
Overall, individuals who engaged in all six healthy behaviors reduced their risk of dementia by about half, compared with those who engaged in two or fewer healthy behaviors. Engaging in three healthy behaviors reduced the risk of dementia by 30%, compared with engaging in two or fewer healthy behaviors, and this association held after controlling not only for family history of dementia, but also for other dementia risk factors such as age, sex, race, and education level, as well as high blood pressure, high cholesterol, and the presence of type 2 diabetes.
Similarly, among participants with a family history of dementia, those who engaged in three healthy lifestyle behaviors showed a 25%-35% reduction in dementia risk, compared with those who engaged in two or fewer healthy behaviors.
The study findings were limited by several factors including the inability to prove that lifestyle can cause or prevent dementia, only to show an association, the researchers noted. Also, the findings were limited by the reliance on self-reports, rather than genetic data, to confirm familial dementia.
However, the findings were strengthened by the large sample size, and the results suggest that a healthy lifestyle can impact cognitive health, and support the value of encouraging healthy behaviors in general, and especially among individuals with a family history of dementia, they said.
Small changes may promote prevention
The study is important now because, as the population ages, many individuals have a family member who has had dementia, said lead author Dr. Brellenthin, in an interview. “It’s important to understand how lifestyle behaviors affect the risk of dementia when it runs in families,” she said.
Dr. Brellenthin said she was surprised by some of the findings. “It was surprising to see that the risk of dementia was reduced with just three healthy behaviors [but was further reduced as you added more behaviors] compared to two or fewer behaviors. However, it was not surprising to see that these same lifestyle behaviors that tend to be good for the heart and body are also good for the brain.”
The evidence that following just three healthy behaviors can reduce the risk of dementia by 25%-35% for individuals with a familial history of dementia has clinical implications, Dr. Brellenthin said. “Many people are already following some of these behaviors like not smoking, so it might be possible to focus on adding just one more behavior, like getting enough sleep, and going from there.”
Dr. Mitchell S. V. Elkind
Commenting on the study, AHA President Mitchell S. V. Elkind, MD, said that the study “tells us that, yes, family history is important [in determining the risk of dementia], and much of that may be driven by genetic factors, but some of that impact can be mitigated or decreased by engaging in those important behaviors that we know are good to maintain brain health.
“The tricky thing, of course, is getting people to engage in these behaviors. That’s where a lot of work in the future will be: changing people’s behavior to become more healthy, and figuring out exactly which behaviors may be the easiest to engage in and be most likely to have public health impact,” added Dr. Elkind, professor of neurology and epidemiology at Columbia University and attending neurologist at New York–Presbyterian/Columbia University Irving Medical Center, New York.
The study received no outside funding, but the was research was conducted using the U.K. Biobank resources. The researchers had no financial conflicts to disclose.