For older adults, chance of developing dementia within the next decade or two depends on your current belly size. Greater the size of your belly, higher the risk of dementia.
For women that risk is particularly high.
According to a study published in the in the International Journal of Epidemiology, for men and women over 50, the dementia risk is 28% when taking body mass index and waist circumference into account together.
For women in later adulthood, above average belly fat can lead to a 39% increased risk of dementia within 15 years compared with those who have a normal waist circumference, the study said.
Researchers measured participants’ height, weight and waist circumference and followed up with them an average of 11 years later to see whether they’d been diagnosed with dementia.
“As belly size gets larger, the memory center in the brain gets smaller, based on prior studies,” said Dr. Richard Isaacson, who heads the Alzheimer’s Prevention Clinic at Weill Cornell Medicine and New York-Presbyterian Hospital.
“This new study is important since it supports these findings and relates a larger waist size to increased dementia risk, especially in women,” said Isaacson, who was not involved in the study.
Dementia is one of the major health challenges of the 21st century that could threaten successful aging of the population.
Obesity and dementia are linked
To examine the link between obesity and dementia, the researchers delved into a cohort of 6,582 subjects within the English Longitudinal Study who were age 50 or higher.
That project, which Steptoe leads, has been monitoring more than 18,000 subjects since 2002, re-interviewing them every other year about topics such as household demographics, social participation, cognitive function and weight.
The BMI findings were a standard ratio of height and weight measures. And the researchers established a patient’s dementia status through measures such as doctor’s diagnosis or hospital records.
To isolate the link between obesity and dementia, the researchers controlled for potential confounding variables such as hypertension, diabetes, smoking and APOE ε4 gene carrier status, a known genetic risk factor for dementia.
Those who developed dementia were an average of 71.8 years old at the time of their baseline assessment. Those who were free of dementia had a mean age of 61.9 years old when they entered the study.
“From a practical clinical perspective, people who want to protect their brain health over time should pay attention to their waist size,” Weill Cornell’s Isaacson said.
He cautioned that simple body mass index scores, which combine height and weight ratios, can’t capture a full picture of weight and obesity. Measures such as muscle mass and waist circumference can tell a more nuanced story.
“Based on emerging data from studies like this, we are now able to clarify sex differences in dementia risk,” Isaacson said. “Combining these findings with my clinical experience, I have seen greater impact on visceral fat on memory function in women, likely mediated by metabolic pathways.”