Healthy habits help preserve brain health, despite genetics
Published on Monday, June 6, 2022
By: Karen Bascom
Simple habits might be the simplest solution to preserving lifelong brain health, according to a new study from the University of Mississippi Medical Center.
The paper, published online May 25 in Neurology, found that people who adhered to the American Heart Association Life’s Simple 7 (LS7) guidelines in midlife had lower rates of dementia decades later. This effect held up for people with increased genetic risk of Alzheimer’s disease. The AHA Life’s Simple 7 are the seven risk factors that people can improve through lifestyle changes, from controlling blood pressure to losing weight.
“Genetics can put an individual at higher risk for late-onset dementia,” said Dr. Adrienne Tin, associate professor of medicine at UMMC and first author of the study. “However, genetics alone does not determine whether an individual would eventually develop dementia.”
Tin, a researcher with The MIND (Memory Impairment and Neurodegenerative Dementia) Center, said a 2020 report found that about 40 percent of the world’s late-onset dementia cases can be tied to 12 modifiable risk factors. These are habits and health factors that people can to some extent control. Seven of them come from the LS7, which the AHA says can prevent heart disease and maintain brain health. They recommend that people manage blood pressure, control cholesterol, reduce blood sugar, get active, eat better, lose weight, and stop smoking.
“However, it was uncertain whether the effects of these seven factors can also be observed among those with high genetic risk,” Tin said.
To find out, the researchers looked at participants in the Atherosclerosis Risk in Communities (ARIC) Study. They included 8,823 people with European ancestry and 2,738 people with African American ancestry who the researchers followed for a median of 26 years.
“ARIC provides over thirty years of data on participants’ cardiovascular risk factors, medical conditions, medications, hospitalizations, and lifestyles, among other things,” said Dr. Gwen Windham, professor of medicine at UMMC and study co-author. “In this study, examining lifestyle behaviors collected at midlife and genetic data from stored blood samples from middle age followed by thirty years of surveillance for dementia outcomes could only be done through a longitudinal design such as ARIC.”
Researchers assigned each participant a midlife LS7 score ranging from 0 to 14 based on data collected at the beginning of the study in the late 1980s. They also calculated a genetic risk score, or GRS, for Alzheimer’s disease for each participant. They checked participants’ DNA for genetic variants known to increase the risk of dementia. One variant, known as APOE ε4, increases risk of Alzheimer’s, but scientists have identified other variants that increase risk as well.
Finally, they noted which participants developed any form of dementia during the course of the study.
Tin found that among participants with European ancestry, people with medium and high LS7 scores had 30 percent and 43 percent lower risk of dementia compared to those with low LS7 scores. Among participants with African American ancestry, medium and high LS7 groups had six percent and 17 percent lower risk than the low LS7 group.
Within each GRS level, Tin and colleagues found that higher LS7 scores were associated with lower dementia risk. Generally, each point higher in Life’s Simple 7 scores was associated with as much as a 10 percent decrease in dementia risk.
“Our findings reinforce the idea that late-onset Alzheimer’s and dementia are due to a combination of modifiable health and genetic factors. Health professionals and individuals can follow the guidance from Life’s Simple 7 to lower the risk of dementia,” Tin said. “With each new study, we are learning that what’s good for the heart is good for the brain.”
Tin notes that one of the study’s limitations is that the African American group is substantially smaller than the European ancestry group.
“Although the findings in European and African American ancestry groups were largely similar, due to the smaller sample size, the estimates among participants of African American ancestry have more uncertainty,” Tin said. “In the future, it would be very informative to conduct similar studies among African Americans with a larger sample size.”
The ARIC Study helps form the basis for The MIND Center, which aims to find new ways to prevent and treat Alzheimer’s disease and other forms of dementia.
“This study is encouraging in that although one cannot change what genes they inherit, it supports the role of our lifestyles, which we can change, to improve brain health and lower risk for developing dementia later in life, even if one has higher genetic risk,” said Windham, director of The MIND Center’s Neuro-Epidemiology Core. “This study emphasizes the importance of lifestyle factors for brain health and therefore a public health need to help people engage in healthy lifestyle behaviors and management of chronic health conditions.”
"There may be other factors that prevent people from having a higher LS7 score, including health care access, access to healthy food, or factors that prevent people from being active," Tin told Medscape. "It's also important to understand the biological connection between these factors and the brain. If we can identify the biological connection, then maybe these connections could serve as therapeutic targets."
The National Institutes of Health funds the ARIC Study. Co-authors of this paper represent the School of Medicine and the John D. Bower School of Population Health at UMMC, Johns Hopkins University, the University of Texas Health Science Center at Houston, and the NIH.