Sporting a girthier waistline and higher body mass index during one’s 60s may be associated with greater signs of brain aging years later, according to a study published this past summer in Neurology, the medical journal of the American Academy of Neurology. The study suggests that these factors may accelerate brain aging by at least a decade.
“People with bigger waists and higher BMI were more likely to have thinning in the cortex area of the brain, which implies that obesity is associated with reduced gray matter of the brain,” said study author and neurologist Tatjana Rundek, MD, PhD. “These associations were especially strong in those who were younger than 65, which adds weight to the theory that having poor health indicators in mid-life may increase the risk for brain aging and problems with memory and thinking skills in later life.”
The study involved 1,289 people with an average age of 64. Their BMI and waist circumference were measured at the beginning of the study. An average of six years later, participants had MRI brain scans to measure the thickness of the cortex area of the brain, overall brain volume and other factors.
A total of 346 of the participants had a BMI of less than 25, which is considered normal weight; 571 people had a BMI of 25 to 30, which is considered overweight; and 372 people had a BMI of 30 or higher, which is considered obese.
For waist circumference, which can be different for men and women, the normal weight group, which was 54 percent women, had an average of 33 inches, the overweight group, which was 56 percent women, had an average of 36 inches, and the obese group, which was 73 percent women, had an average of 41 inches.
After researchers adjusted for factors that could affect the cortex (ie, high blood pressure, alcohol use and smoking), the researchers found a correlation of higher BMI and larger waist with a thinner cortex. In overweight people, every unit increase in BMI was associated with an approximate .09 millimeter (mm) thinner cortex—and in obese individuals with a 0.207 mm thinner cortex. Having a thinner cortex is associated with an increased risk of Alzheimer’s disease.
Rundek said, “In normal aging adults, the overall thinning rate of the cortical mantle is between 0.01 and 0.10 mm per decade, and our results would indicate that being overweight or obese may accelerate aging in the brain by at least a decade.”
These results emphasize another benefit of losing weight and getting in shape, even in one’s 60s—they may be able to stave off aging of their brains and potentially the memory and thinking problems that often stem from brain aging. Rundek noted that the study does not prove that extra weight causes the cortex to get thinner; it only shows an association.
Reference:
Caunca, et al. “Measures of obesity are associated with MRI markers of brain aging The Northern Manhattan Study.” Neurology, 2019 DOI: 10.1212/WNL.0000000000007966
