Add 'memory boost' to weight-loss surgery's potential benefits

Losing weight might not only help your waistline, but just maybe your memory too. A new, small study would seem to suggest that obese patients who have their fat surgically removed show improvements in memory and concentration when compared to obese people who didn't have surgery.

Researchers from Kent State University in Ohio gave a cognitive and memory test to 150 obese patients in New York and North Dakota. The tasks involved navigating through computer mazes and recalling word lists and as many animal names as possible in 60 seconds. Many of the patients scored in the low-average to average range. Then, about two-thirds of the group — 109 patients — underwent bariatric weight-loss surgery (104 had gastric bypass surgery and 5 had adjustable gastric bands implanted) through which they shed on average 17% of their body weight.

When all the patients were retested 12 weeks later the ones who had the surgery tested within average to above-average ranges, while the group that didn't have the surgery actually tested slightly worse — from the middle range of mild impairment to the low end, the team reported. The findings have been reported online and are to be published in print in the journal Surgery for Obesity and Related Diseases.

Changes in blood pressure seemed to have an especially significant effect: The surgery patients who lowered their blood pressure got better at recalling vocabulary words 12 weeks later than those whose blood pressure didn't change, researchers found.

The results seem exciting — who wouldn't want to be trimmer and smarter? But it's worth repeating that the study was small, only 150 people. Effects seen in a small number of people can disappear in a larger group.

And one finding in this study should give pause: Why would the control group — the 41 people who didn't have surgery — have lower cognitive scores in just three months?

People usually have slight improvements when taking the test the second time around, acknowledged John Gunstad, a psychologist at Kent State who led the research. One wouldn't expect such a fast change in a group of people with moderate dementia, much less in a random sampling of obese patients without moderate dementia. Gunstad said the researchers can't rule out that some situation effect is going on.

Nor are the researchers clear why shedding pounds would help the brain function better, but that's what they attributed the memory improvements to.

If they're right, the mechanism is probably complicated.

"It appears blood pressure is at least part of the explanation," said Gunstad. "But it doesn't explain all the pieces." Cardiovascular fitness is known to help cognitive ability, as is improved blood sugar control. Gunstad thinks there are probably many more factors at play.

But the conclusion does echo the results from a study last year that found that every one-point increase in body mass index (BMI) corresponds to a decline in cognitive ability (at least in postmenopausal women).

And with more study, cognitive improvements might be added to a growing list of potential benefits of bariatric surgery: increased longevity (surgery may be able to buy about three extra years), treating diabetes, lowering blood pressure and treating high cholesterol.

That's not to say weight-loss surgery is without risks. So no one, not us anyway, is suggesting a rush to conclusions — unless it's to address some of the potential health risks without surgery first.

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