Beyond the Genes
Following a healthy lifestyle is associated with a lower risk of dementia in cognitively healthy older adults at varying levels of genetic risk for Alzheimer’s disease and related dementias, according to a study recently published in the Journal of the American Medical Assoc. Funded in part by the National Institute on Aging, the study is the first to examine the relationship between multiple genetic risk factors for dementia and multiple lifestyle factors.
Researchers led by the University of Exeter Medical School in the United Kingdom analyzed data from 196,383 participants, age 60 and older, who did not have cognitive impairment or dementia when they joined the UK Biobank study between 2006 and 2010. Using polygenetic risk scores based on previously published Alzheimer’s disease genome-wide association studies, researchers sorted participants into levels of genetic risk for dementia (low, intermediate, and high). Participants were also assigned a healthy-lifestyle score (favorable, intermediate, and unfavorable) based on self-reports of their current smoking status, regular physical activity, healthy diet, and moderate alcohol consumption.
“Higher levels of genetic risk were still associated with increased risk of incident dementia at every level of lifestyle.”
Over a median eight years of follow-up, 1,769 participants developed dementia. The researchers found that, in participants at high genetic risk for dementia, a favorable lifestyle was associated with lower dementia risk than in those with an unfavorable lifestyle. However, scores for genetic risk and healthy lifestyle were independently associated with dementia risk — that is, following a healthy lifestyle was associated with lower dementia risk for participants at all levels of genetic risk, but higher levels of genetic risk were still associated with increased risk of incident dementia at every level of lifestyle.
The authors noted that additional research is necessary given some of the study’s limitations. The participants studied were limited to those of European ancestry, and they volunteered rather than being randomly selected from a sampling frame, making it difficult to generalize to other populations. Also, the average age of the participants at the end of the follow-up period was 72, so the incident dementia cases were relatively low despite the large number of participants tracked. Finally, the crucial lifestyle variables were self-reported by participants rather than being objectively observed.
Information provided by the National Institute on Aging.