A nationally representative US study followed more than 8,200 people over the age of 50 for 24 years. The researchers measured body mass index (BMI) repeatedly and gave tests of memory and executive function. Executive function covers skills such as managing emotions, organizing tasks, planning, and concentrating.
The analysis showed that higher BMI over time was associated with more rapid declines in cognitive abilities. The authors reported that every unit increase in BMI was linked to a faster decline and that the strongest correlation appeared at year eight of the study. The effect was most pronounced in adults over 65.
Obesity, defined as BMI 30 or higher, was associated with negative effects on brain health. The researchers suggested likely biological processes — inflammation, reduced blood flow to the brain, and insulin resistance — that may lead to cognitive impairment, Alzheimer’s disease and related dementias. They add that weight management could significantly lower the rate of cognitive decline in as little as two years. The study was reported by the University of Georgia and appears in the Journal of Neurology.
In the United States, the Centers for Disease Control and Prevention say two out of every five Americans are considered obese by BMI alone; a broader definition that also includes waist size and weight-related health conditions raises that share to 75 percent. More than 7 million people in the US currently live with dementia, and that number is expected to double by 2050.
Difficult words
- body mass index — measure using weight and height to assess fatBMI
- executive function — mental skills for planning and controlling actions
- cognitive — related to thinking, memory and understanding
- obesity — very high body fat that harms health
- inflammation — body reaction that causes redness and swelling
- insulin resistance — body condition reducing response to insulin
- dementia — condition causing loss of memory and thinkingdementias
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Do you think weight management could reduce risk of memory loss? Why or why not?
- What actions could local communities take to help adults over 65 protect brain health?
- How does a long study (24 years) give different information than a short study in your view?
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