There are countless factors that may contribute to the risk of developing dementia, from genetics to blood pressure levels. Now, it turns out that your waist size may also be a marker for dementia.
A new study, conducted by researchers at Korea University Guro Hospital and published in Obesity, finds that abdominal obesity—or a larger waist size—was associated with a greatly increased risk of developing dementia.
The researchers focused on a data set of 872,082 participants in the 2009 Korean national health screening, who were aged 65 and older. They tracked participants until they developed dementia or died, up until December 2015. Participants’ smoking levels, age, exercise, alcohol use and medical history were also tracked.
They also measured BMI, or body mass index, which is an indicator for obesity and health. A higher BMI can typically be a sign of being overweight. The researchers also analyzed waist size, measured between the lower part of the rib cage and the iliac crest on the hips.
Participants who had a waist size of larger or equal to 90 centimeters for men, and 85 centimeters for women, had a greater risk of dementia—even when the researchers adjusted for other factors (age, BMI, blood pressure and cholesterol).
“This study emphasizes that waist circumference should be considered in the assessment of obesity-related dementia risk in the elderly,” Hye Jin Yoo, associate professor at Korea University Guro Hospital and an author of the study, said in a news release.
However, the study also found that people who had a low BMI and were considered underweight actually had a higher risk of dementia compared to people with a normal BMI and weight, which leaves some questions unanswered.
“This study does not let us know why there is this discrepancy but may point to the different roles of subcutaneous fat versus visceral fat,” Dr. Dan Bessesen of the University of Colorado School of Medicine, who was not involved in the research, said in the news release.
Subcutaneous fat is the type of soft fat that lies right under the skin, according to Harvard Health. 90 percent of body fat is subcutaneous, and it’s been linked to more negative health problems. Visceral fat, meanwhile, is stored in between organs. More research will be needed to identify what kind of fat may contribute to dementia risk.
Weight and Cognitive Health
Research has established a link between belly fat and waist size, and brain health, in the past. One 2019 study found that extra body fat around the waist correlated with shrinking brain size, which is linked to memory and cognitive decline. Researchers identified a trend: People who had a higher BMI tended to have smaller brain volume.
Fortunately, unlike your genetic profile, there’s something you can do about this particular risk factor.
The researchers write that “dementia is regarded as a preventable condition with many possible modifiable risk factors,” noting that obesity is “one such modifiable risk factor.”
In fact, recent research discovered that certain lifestyle changes — like eating a healthier diet, sticking to an exercise routine and improving sleep — could act as an intervention of sorts and slow cognitive decline. Some experts even say that with these lifestyle changes, a third of dementia cases could be preventable.