Oct. 11, 2010 (San Diego) -- Bariatric or weight loss surgery may improve memory, according to new research, which also found no adverse effects on other cognitive skills such as attention or language.

"Just three months after surgery, there was a significant improvement in memory function," says researcher Gladys Strain, PhD, director of research for laparoscopic and bariatric surgery at Weill Cornell Medical College in New York, who presented her findings at Obesity 2010, the annual meeting of the Obesity Society in San Diego.

Obesity is linked with a host of health problems, including a higher risk of stroke and Alzheimer's disease, Strain says. Growing evidence also suggests that obesity is associated with problems in cognition.

While bariatric surgery, such as gastric bypass, has been shown to be effective as an obesity treatment, its effects on cognition have not been well studied, she says.

All major surgery, including bariatric procedures, includes some risk of cognitive problems, Strain says. Patients may worry about the effects anesthesia has on their thinking skills. Nutritional deficiencies after surgery may boost the risk of cognitive performance problems, she says.

Some previous research by others found that bariatric patients who become vitamin deficient can suffer memory loss and other cognitive problems.

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Bariatric Surgery and Cognition

Strain compared 120 patients who had bariatric surgery as participants in the Longitudinal Assessment of Bariatric Surgery study, funded by the National Institutes of Health, with 60 obese patients who did not have the surgery.

While the groups were similar in age, Strain says their body mass index (BMI) differed, with the non-surgery group having lower, or healthier, BMIs. Most surgery patients had gastric bypass, while a handful had the banding procedure.

Both groups took a battery of computerized cognitive tests at the start of the study and then 12 weeks later, after the surgery had been done.

Strain tested four skills: attention, executive function, memory, and language. Executive function refers to a set of abilities that regulate other abilities, such as being able to think abstractly.

For attention, executive function, and language, "there were no changes during that three months," she says of the patients. But the surprise was the improvement in memory among the surgery patients, an improvement not found in the comparison group.

Memory skills tested including learning, short-term recall, long-term recall, and recognition.

"Postoperative changes may be associated with cognitive benefit," Strain says. A patient may or may not notice the memory improvement, she tells WebMD, as it may be modest.

Exactly why the surgery improved memory isn't clear, she says. One possibility is the resolution of depression. "Bariatric patients have an increased incidence of depressive disorders and anxiety and sedentary lifestyles," she says. As they lose weight, that depression may lift, perhaps explaining the improvement in cognitive skills, she says.

She says more research is needed to focus on the exact mechanisms. Ideally, she would like to test patients for longer intervals after surgery.

Second Opinion

The findings are not surprising to Julie Schwartz, RD, a dietitian in Suwanee, Ga., who reviewed the findings for WebMD. She often counsels patients with weight issues.

"Before surgery, people are depressed and anxious, and often their self-confidence and self-esteem are low," she tells WebMD. "Post-surgery, by three months, there is usually significant weight loss."

She notices improvement in patients' confidence and image at that point, as well. Other improvements, such as a decline in insulin resistance, are known to occur, too, she says.

It makes sense that those improvements could improve memory, Schwartz says.

This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.