Risk of dementia can be significantly reduced with regular exercise and proper diet no matter what your genes say
A healthy lifestyle can substantially reduce the risk of dementia, irrespective of genetic risk. The findings were published simultaneously in JAMA and presented recently at the Alzheimer's Association International Conference 2019 in Los Angeles. This is the first such study to state it is not inevitable that a person will develop dementia because of their genetics, and they can offset it with healthy behaviors such as regular physical activity, healthy diet, no smoking, and drinking alcohol in moderation.
"Among older adults without cognitive impairment or dementia, both an unfavorable lifestyle and high genetic risk are significantly associated with a higher risk of dementia. A favorable lifestyle was associated with lower dementia risk among participants with a high genetic risk. To our knowledge, no previous study has investigated the association between a combination of lifestyle factors and multiple genetic risk factors and dementia incidence,” say the researchers in their findings.
The risk of dementia was 32% lower in people with a high genetic risk if they had followed a healthy lifestyle, compared to those who had an unhealthy lifestyle, shows the observational study.
"The study delivers an important message that undermines a fatalistic view of dementia. Some people believe it's inevitable they will develop dementia because of their genetics. However it appears that you may be able to substantially reduce your dementia risk by living a healthy lifestyle," says joint lead author Dr. David Llewellyn, from the University of Exeter Medical School and the Alan Turing Institute.
According to the World Health Organization (WHO), approximately 50 million people worldwide have dementia, and it is now the fifth leading cause of death. "Dementia is an umbrella term for several diseases affecting memory, other cognitive abilities, and behavior that interfere significantly with a person’s ability to maintain their activities of daily living. Although age is the strongest known risk factor for dementia, it is not a normal part of aging," says WHO.
Genetic factors are associated with increased risk of dementia, but to what extent lifestyle factors might offset these was not known so far. Led by the University of Exeter in collaboration with researchers from the University of Michigan, the University of Oxford, and the University of South Australia, the study examined data from 196,383 adults of European ancestry, who were aged at least 60 years of age without cognitive impairment or dementia at baseline.
Participants joined the UK Biobank study from 2006 to 2010 and were followed up until 2016 or 2017. Over eight years of follow-up, there were 1,769 new cases of dementia. The researchers grouped the participants into those with high, intermediate, and low genetic risk for dementia.
The team evaluated published data and identified all known genetic risk factors for Alzheimer’s disease. “Each genetic risk factor was weighted according to the strength of its association with Alzheimer’s disease,” says the findings. The researchers also categorized the participants into favorable, intermediate, and unfavorable categories based on their self-reported diet, physical activity, smoking, and alcohol consumption. This was done to assess their lifestyle choices and behaviors over a period of time.
The analysis shows that participants with high genetic risk and an unfavorable lifestyle were almost three times more likely to develop dementia compared to those with low genetic risk and a favorable lifestyle. Individuals who did not smoke, were physically active, had a healthy diet, and reported moderate alcohol consumption were categorized as those with healthy behaviors.
"Both an unfavorable (the least healthy) lifestyle and high genetic risk were associated with higher dementia risk compared with low genetic risk and a favorable (the most healthy) lifestyle score. A favorable lifestyle was associated with lower dementia risk regardless of genetic risk, indicating that genetic risk and a healthy lifestyle are independently associated with risk of dementia," says the team.
The findings show that among participants with a high genetic risk, 1.23% developed dementia as compared to 0.63% of participants with low genetic risk. Of the participants with high genetic risk and unfavorable lifestyle, 1.78% developed dementia compared with 0.56% with low genetic risk and favorable lifestyle, says the paper. Further, among participants with high genetic risk, 1.13% of those with a favorable lifestyle developed dementia compared with 1.78% with an unfavorable lifestyle.
"Living a healthy lifestyle was associated with a reduced dementia risk across all genetic risk groups. The absolute risk reduction for dementia of a favorable lifestyle compared with an unfavorable lifestyle among the high genetic risk group was 0.65%. This risk reduction implies that, if the lifestyle is causal, 1 case of dementia would be prevented for every 121 individuals per 10 years with high genetic risk who improved their lifestyle from unfavorable to favorable," states the paper.