In a new study, researchers found waist circumference is a more accurate indicator of abdominal visceral fat level than body mass index (BMI) in the elderly.
They found that high waist circumference is associated with a higher risk of obesity-related dementia.
The study is the first large-scale cohort to examine the association of late-life waist circumference with the incidence of dementia in older people.
The research was conducted by a team from Korea University Guro Hospital and elsewhere.
A 2015 large-scale retrospective cohort study of nearly 2 million people showed that the incidence of dementia continued to fall for every increasing BMI category.
Two Mendelian randomization studies showed no link between obesity and dementia.
BMI is not a perfect measure of adiposity because it cannot discriminate between fat and lean body mass.
Studies have been limited and had focused on the relationship between waist circumference and dementia in older persons.
One study showed that central adiposity, represented by waist circumference, predicted an increased risk for the cognitive decline during a 2-year follow-up period in older patients with diabetes.
Another study reported that waist circumference was correlated with lower overall cognition and executive performance in older women with type 2 diabetes.
To help determine a healthy waist circumference, researchers compared the relative risk of dementia associated with waist circumference and BMI categories using the Korea National Health Insurance Service program.
The program is a mandatory social health insurance program that enrolls about 98 percent of Koreans.
The team found people with a waist circumference of greater than or equal to 90 cm for men and 85 for women had a significantly increased risk of dementia.
The team says alternatively BMI might be more related to lean mass in older people and the relationship with BMI and dementia may be more a result of the adverse effects of sarcopenia in the elderly.
The study was done in an Asian population, so it would benefit from confirmatory studies in other populations.
However, it suggests that visceral obesity may be associated with an increased risk of dementia.
One author of the study is Hye Jin Yoo, associate professor at Korea University Guro Hospital.
The study is published in Obesity.
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