So you don’t exercise. And you like your six pack. And you have a bit of a pot belly. But you are not overweight. In fact, your BMI is in the normal range. Do you feel pretty smug? Read on, and I think you’ll get shaken up a bit, as you should.

 

Central obesity

The correlation between obesity and diabetes and heart disease is well known. In fact, we now know that people should be concerned not only about body fat, but, importantly, where this fat is located. Waistline fat is a major risk factor for diabetes and heart disease, deceptively cute names like “love handles” notwithstanding. But did you know that being a Michelin Man may end up in dementia?

 

The Kaiser study

I certainly did not suspect it. And I dare say, I don’t know anybody in the medical community who has.

Now comes a wonderful study, led by Rachel A. Whitmer of the famed Research Division of Kaiser Permanente in Oakland, CA, that tells us a very disturbing tale.

The investigators took advantage of the extensive medical records kept by Kaiser about their members. They conducted a longitudinal study of 6,583 members of Kaiser Permanente of Northern California who had their sagittal abdominal diameter (SAD) measured in 1964 to 1973. Diagnoses of dementia were from medical records an average of 36 years later (!), January 1, 1994 to June 16, 2006. Where else, with the possible exception of the Scandinavian countries, could you get such a long follow-up? And who else would pay for sagittal sections of the abdomen to carry out such a study? Only Kaiser Permanente, which is a non-profit HMO, with “non-profit” being the operative word. Before I go on, sagittal sections divide the body into left and right portions.

Bottom line: Sagittal sections allow the determination of a pot belly size with great accuracy.

 

And the surprising results

A total of 1,049 participants (15.9%) were diagnosed with dementia. Compared with those in the lowest quintile of SAD, those in the highest had nearly a threefold increased risk of dementia (hazard ratio, 2.72). Now, you’d think that obesity, in general, could explain this astonishing finding. But when the BMI (body mass index) was taken into account, the hazard ratio or risk of dementia, was 1.92, or about twofold.

Those with high SAD (>25 cm, or 10 inch) and normal BMI had an increased risk (hazard ratio, 1.89) vs. those with low SAD (<25 cm) and normal BMI (18.5–24.9 kg/m2), whereas those both obese (BMI >30 kg/m2) and with high SAD had the highest risk of dementia (HR, 3.60). In other words, if you are not obese, but have those cute love handles, your risk is double that of “normal”. And if you are obese and blessed with central obesity, then your risk of developing dementia increases 4-fold! Food for thought, while you still can.

Even more alarming: These subjects had central obesity since middle age. And you can’t find refuge in your good numbers; the association held after correcting for high cholesterol, high blood pressure, diabetes, heart disease, stroke, and other variables. And if you think that your sex will shield you, it won’t—the results were the same for men and women.

As far as I know, this is the first time that anybody studied the correlation between central obesity and dementia. Nobody has a clue how this works on the physiological or molecular level, but rest assured, researchers will rush in to investigate this surprising finding.

But for now, all I can say is thank you Kaiser Permanente for this great study.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.