Healthy lifestyle behaviors reduced dementia risk despite family history of dementia
Adopting healthy lifestyle behaviors can lower dementia risk among people who are at higher risk due to a family history of dementia, according to preliminary research to be presented at the American Heart Association's Epidemiology, Prevention, Lifestyle & Cardiometabolic Health Conference 2021.
Familial dementia is a strong risk factor for dementia. Having a first-degree relative such as a parent or sibling with the disease can increase a person's risk of dementia by nearly 75% compared to someone who does not have a first-degree relative with the condition. Other common risk factors for dementia include age, sex, race, education, high blood pressure, high cholesterol, Type 2 diabetes and depression.
"When dementia runs in a family both genetics and non-genetic factors, such as dietary patterns, physical activity and smoking status, affect an individual's overall risk," said study author Angelique Brellenthin, Ph.D., assistant professor of kinesiology at Iowa State University in Ames, Iowa. "This means there may be opportunities for reducing risk by addressing those non-genetic factors."
Brellenthin and colleagues analyzed health information on 302,239 men and women, ages 50-73 years, who completed a baseline physical examination between 2006-2010 as part of the UK Biobank Study, which is a large study encompassing over 500,000 people in the United Kingdom. The adults were free of dementia at the beginning of the study and filled out questionnaires about family history and lifestyle. Participants were given one point for each of six healthy lifestyle behaviors they followed, including:
- Eating a healthy diet with more fruits and vegetables, and less processed meat and refined grains;
- Meeting physical activity guidelines of 150 or more minutes a week of moderate-to- vigorous physical activity;
- Sleeping 6 to 9 hours each day;
- Drinking alcohol in moderation;
- Not smoking; and
- Not having obesity, meaning they had a BMI (body mass index) of <30 kg/m.
Researchers then followed the study participants for about eight years to monitor who did and did not develop dementia. They found:
- During the follow-up, 1,698 (0.6%) participants developed dementia. Adults with a family history of dementia had about a 70% increased risk of dementia compared to those who did not have a family history of dementia.
- Following all six healthy lifestyle behaviors cut the risk of dementia by nearly half compared to following two or fewer healthy behaviors,
- In general, following three of the healthy behaviors was associated with a 30% reduced risk of dementia compared to following two or fewer behaviors, even when investigators considered familial dementia and more common risk factors for dementia like age, sex, race, education, high blood pressure, high cholesterol, Type 2 diabetes and depression.
- Participants with familial dementia who followed at least three healthy lifestyle behaviors had a 25% to 35% reduced risk of dementia compared to those with familial dementia who followed two or fewer healthy behaviors.
Researchers said these results suggest that starting with small changes, like engaging at least three or more healthy lifestyle behaviors, can significantly lower the risk of dementia even for those at higher risk due to a family history of dementia.
"It was interesting to find that participants who followed more of the healthy behaviors at baseline actually also reported more familial dementia at baseline," Brellenthin said. "For example, there was an 11% prevalence of familial dementia among those following two or fewer healthy behaviors, compared to 15% prevalence of familial dementia among those following all six healthy lifestyle behaviors. And individuals who followed more healthy behaviors were less likely to develop dementia in general."
Brellenthin noted this might suggest that individuals who know they have an increased risk of dementia are proactive and already taking important healthy steps to reduce their risk.
Limitations of the study include that it did not prove that lifestyle can cause or prevent dementia, only that they are associated. And the investigators did not have actual genetic data to confirm familial dementia, they relied on questionnaires completed by the study participants.
"This study provides important evidence that a healthy lifestyle can have a positive impact on brain health," said American Heart Association President Mitchell S.V. Elkind, M.D., M.S., FAHA, FAAN, professor of neurology and epidemiology at Vagelos College of Physicians and Surgeons and at the Mailman School of Public Health and an attending neurologist at New York-Presbyterian/Columbia University Irving Medical Center. "It 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."