Weight-loss surgery may help individuals not only shed pounds but improve their memory and concentration.

Obese people participating in a new study were tested on their mental abilities. They showed, on average, slightly impaired memory and concentration. Twelve weeks after surgery, subjects' scores registered in the normal range. Meanwhile, the obese study participants who did not undergo surgery actually showed a decline in their mental abilities over those 12 weeks, but the researchers aren't sure why this occured.

The study is the first to look at changes in mental abilities after bariatric surgery, which can result in a large amount of weight loss in a short period of time. The study shows "the obesity-related cognitive effects might be at least partly reversible," said study researcher John Gunstad, an associate professor at Kent State University in Ohio. "It also provides potentially additional motivation for people who are thinking about losing weight."

However, further research is needed to confirm the results and to understand what, exactly, is responsible for the improvement in memory, Gunstad said.

The study adds to a growing body of research linking obesity to memory deficits and to an increased risk for Alzheimer's disease and other types of dementia.

Bariatric surgery is not without its own risks. A recent study found that many patients who receive gastric bands experience complications over the long term.

Weight loss and memory

The study involved 150 individuals whose average weight was about 300 pounds (136 kilograms); 109 of them underwent weight-loss surgery.

Most of the procedures were gastric bypass surgery, in which the stomach is stapled to turn it into a small pouch, and a portion of the intestine is rerouted so that it is attached to a different part of the stomach. A few of the patients received gastric banding instead, which involves placing a band around the top portion of the stomach to restrict the amount of food it can hold.

All the participants underwent a battery of tests to assess their cognition beforehand. In some, participants were read a list of words (or numbers) and were asked to recall them at a later time.

Participants showed mild impairments on the initial tests. Theses impairments might translate into difficulties in carrying out everyday activities, such as following instructions, Gunstad said.

Twelve weeks later, the surgery participants had lost about 50 pounds, Gunstad said. They improved on all four tests designed to assess memory, while the non-surgical subjects performed worse on two of these tests and about the same on the others.

Future work

The researchers aren't exactly sure why the surgery patients showed improved memory, though changes in blood pressure may be partly responsible.

"We've known for a long time that high blood pressure is bad for all parts of the body, including the brain," Gunstad said.

However, the study found the weight loss itself could not directly explain the memory improvements, suggesting there were other factors tied to the surgery or weight loss, Gunstad said.

The future research will examine whether weight loss achieved through non-surgical means produces the same changes in memory, Gunstad said.

The study will be published in an upcoming issue of the journal Surgery for Obesity and Related Diseases.

Pass it on: Obese individuals who undergo weight-loss surgery may boost their memory.

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This story was provided by MyHealthNewsDaily, a sister site to LiveScience.