Healthy lifestyle behaviors may offset someone's genetic risk of dementia, according to a new study, "Association of Lifestyle and Genetic Risk With Incidence of Dementia," published in JAMA and presented on July 14 at the Alzheimer's Association International Conference (AAIC 2019) in Los Angeles. This study was spearheaded by scientists at the University of Exeter in collaboration with researchers from the University of Oxford, the University of South Australia, and the University of Michigan.
After analyzing data from 196,383 adults (all 60-plus years old) of European ancestry from the UK Biobank, the international team concluded that participants with a high genetic risk for dementia who lived a healthy lifestyle had a 32 percent lower risk of dementia than peers who lived an unhealthy lifestyle.
Notably, participants who were at a high risk for dementia and led an unhealthy lifestyle were three times more likely to develop dementia in comparison to someone with a low genetic risk who led a healthy lifestyle. The four lifestyle habits examined for this study were: (1) weekly physical activity, (2) diet, (3) smoking, and (4) alcohol consumption.
The researchers consider "no current smoking, regular physical activity, healthy diet, and moderate alcohol consumption" to be healthy lifestyle behaviors associated with lower dementia risk. Although this study only focused on four behaviors, the authors acknowledge that other lifestyle factors (e.g., sleep, social engagement, cognitive activities) might also affect dementia risk.
"This is the first study to analyze the extent to which you may offset your genetic risk of dementia by living a healthy lifestyle. Our findings are exciting as they show that we can take action to try to offset our genetic risk for dementia. Sticking to a healthy lifestyle was associated with a reduced risk of dementia, regardless of the genetic risk," joint lead author Elżbieta Kuźma of the University of Exeter Medical School said in a statement.
Although these findings by Lourida et al. (2019) on a possible link between healthy lifestyle behaviors and lower risk of dementia are promising, it's important to note that this study has several limitations. In the discussion section of their paper, the authors list nine specific limitations, for example:
"First, unlike the genetic variants, adherence to a healthy lifestyle was not randomly assigned. Second, the lifestyle score has not been independently validated to indicate a high-risk lifestyle outside of this study. Third, although analyses were adjusted for known potential sources of bias and participants were followed up for a median of 8 years, the possibility of unmeasured confounding and reverse causation remains. Fourth, lifestyle factors were self-reported and some cases of dementia are not recorded in medical records or death registers. "
Despite a laundry list of limitations, this research offers hope that making healthier day-to-day lifestyle choices—all of which are within someone's locus of control—may reduce dementia risk. "This research delivers a really important message that undermines a fatalistic view of dementia. Some people believe it's inevitable they'll 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," joint lead author David Llewellyn of the University of Exeter Medical School and the Alan Turing Institute said in a statement.
Note: Another "Lifestyle and Risk for Cognitive Decline" presentation this week at AAIC 2019 identified an association between healthy lifestyle behaviors and lower risk of dementia. The Washington Post reported on these findings in a July 14 article based on soon-to-be-published research by Klodian Dhana and colleagues at Rush University Medical Center in Chicago.
Ilianna Lourida, Eilis Hannon, Thomas J. Littlejohns, Kenneth M. Langa, Elina Hyppönen, Elżbieta Kuźma, David J. Llewellyn. "Association of Lifestyle and Genetic Risk With Incidence of Dementia." JAMA (First published online: July 14, 2019) DOI: 10.1001/jama.2019.9879