Bottom Line: This observational study looked at whether a healthy lifestyle was associated with a lower risk of dementia regardless of genetic risk. Genetic factors are associated with increased risk of dementia but to what extent these might be offset by lifestyle factors is unknown. Genetic information from the UK Biobank was available for the 196,383 adults in this study who were of European ancestry, at least 60 years old and without dementia at the study baseline. Scores reflecting genetic risk and lifestyle were compiled based on genetic variants associated with Alzheimer disease and dementia and questionnaires about smoking, physical activity, diet and alcohol consumption. Over eight years of follow-up, there were 1,769 new cases of dementia. 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 healthy lifestyle are independently associated with risk of dementia. The study has a number of limitations including that it cannot show causality, lifestyle factors were self-reported and the study was restricted to adults of European ancestry so it may not be generalizable to other populations.
Authors: David J. Llewellyn, Ph.D., University of Exeter Medical School, Exeter, United Kingdom, and coauthors
(doi:10.1001/jama.2019.9879)
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