As belly size gets larger, the memory center in the brain gets smaller

Researchers at University College London link waist circumference with dementia.

As belly size gets larger, the memory center in the brain gets smaller

Over one in eight adults are now obese -- a ratio that has more than doubled since 1975 and will swell to one in five by 2025, a major survey reported April 1, 2016.

Photos: Robyn Beck, Ronaldo Schemidt, Paul Ellis/AFP via Getty Images
  • Researchers at University College London have discovered a link between waist circumference and dementia.
  • Seventy-four percent of volunteers that developed dementia were overweight or obese.
  • Women with central obesity had a 39 percent greater risk of dementia.

One of every eight deaths in England was attributed to dementia in 2017. Considering the substantial public health burden this adds to a society, researchers at University College London wanted to understand the role of obesity on cognitive decline. A new study, published in the International Journal of Epidemiology, sheds light on this connection.

Obesity impacts a range of health problems, including cardiovascular disease, diabetes, stroke, and dementia. Around the planet, obesity rates in adults have tripled since 1975. In 2016, an estimated 39 percent of adults in England were obese.

The researchers specifically wanted to know if waist circumference (WC) plays a role in increasing dementia rates. The team pulled data from 6,582 participants from the English Longitudinal Study of Ageing, an 18-year study (so far) featuring over 18,000 volunteers.

For this study, adults over age 50 were considered. They were broken into normal weight, overweight, and obese groups. Body Mass Index (BMI) was one of two markers used. The relevance of this particular measurement—(Weight in Pounds x 703) / (Height in inches x Height in inches)—has long been contested. It does not account for muscle mass or how fat is distributed throughout the body.

The WC measurement, which the researchers refer to as central obesity, adds a bit of clarity to the study. They define excess central obesity as 35+ inches for women and 40+ inches for men.

In total, 6.9 percent of volunteers developed dementia over a (maximum) 15-year follow-up period. Seventy-four percent of participants that developed dementia were overweight or obese. These findings are independent of demographics, lifestyle behaviors, hypertension, diabetes, and APOE E-ε4, a genetic risk factor for dementia.

Notably, women with excessive central obesity had a 39 percent greater risk of developing dementia compared with non-central obese women.

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Co-author Andrew Steptoe, a professor of psychology and epidemiology at the university, sums up the team's work:

"Dementia is one of the major health challenges of the 21st century that could threaten successful aging of the population. Our findings suggest that rising obesity rates will compound the issue."

Dr. Dorina Cadar, a senior fellow at UCL and corresponding author of the study, suggests monitoring both BMI and WC status. Her suggestions include following a Mediterranean diet, reducing alcohol consumption, and regular exercise.

Dr. Richard Isaacson, the director of the Alzheimer's Prevention Clinic at Weill Cornell Medical College, says that brain health and waist size are linked, especially for women.

"Based on emerging data from studies like this, we are now able to clarify sex differences in dementia risk. 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."

This is another in a long list of studies linking obesity to cognitive problems, and serves as a reminder as to why exercise and nutrition remain your best defense against dementia. Regardless of the conveniences of modern society, human beings evolved during times of scarcity. We're not built for excess. Our brains pay the price when we indulge.


Stay in touch with Derek on Twitter, Facebook and Substack. His next book is "Hero's Dose: The Case For Psychedelics in Ritual and Therapy."

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