In a study from The Ohio State University and elsewhere, scientists found the risk factors linked to cognitive decline in older adults explain a surprisingly modest amount about the large variation in mental abilities between older people.
They found that the factors most commonly associated with cognitive functioning—including socioeconomic status, education and race—explained only 38% of the variation in functioning among Americans at age 54.
Health behaviors such as avoiding obesity and smoking and participating in vigorous exercise had only very small effects on functioning by the time people reached their mid-50s.
In addition, the factors studied explained only 5.6% of the variation in how quickly cognitive functioning declined in people between age 54 and 85.
In the study, researchers used data came from 7,068 participants in the 1996-2016 Health and Retirement Study. Participants were born between 1931 and 1941.
They measured their cognitive functioning at age 54 and how it declined until they were 85.
The team found the most important predictor of cognitive functioning at age 54 was education, which explained about 25% of the difference between people.
That was followed by race, household wealth and income, parental education, occupation and depression.
The contributions of chronic diseases, health behaviors, gender, marital status and religion were rather small—less than 5%.
The researchers found that the variation in cognitive functioning at age 54 was three times as much as the variation in how quickly the participants declined over the next 30 years.
Overall, all the factors examined in this study only explained 5.6% of variation in the decline of cognitive functioning with age.
This suggests it is much more important to try to improve functioning at the baseline than trying to slow down the rate of decline.
One explanation for declines in cognitive functioning that this study could not account for is a genetic factor—the APOE4 gene. That gene has been found to increase the risk of developing dementia, including Alzheimer’s disease.
But other studies show that dementia, including Alzheimer’s disease, accounts for only 41% of cognitive decline among the elderly.
If you care about brain health, please read studies about how the Mediterranean diet could protect your brain health, and blueberry supplements may prevent cognitive decline.
For more information about brain health, please see recent studies about antioxidants that could help reduce dementia risk, and Coconut oil could help improve cognitive function in Alzheimer’s.
The study was conducted by Hui Zheng et al and published in the journal PLOS ONE.
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