ATLANTA – Higher baseline levels of cognitive impairment are associated with poorer weight loss outcomes after bariatric surgery.
"People with problems of memory, problem solving, or attention prior to surgery show reduced ability to lose weight," said John Gunstad, Ph.D., at Obesity Week, presented by the Obesity Society and the American Society for Metabolic and Bariatric Surgery.
In a prospective study of 109 bariatric surgery patients enrolled in the LABS (Longitudinal Assessment of Bariatric Surgery) study and 41 obese matched controls who’d not had surgery, Dr. Gunstad, who is professor and chairman of neuroscience at Kent (Ohio) State University, and his colleagues assessed all participants’ cognitive function at baseline, at 12 weeks, and at 12, 24, and 36 months.
Dr. John Gunstad
They found that 25% of all surgical patients had baseline cognitive impairment. "These were individuals who were at least 1.5 standard deviations below normal-weight persons in at least one cognitive domain," said Dr. Gunstad. "If these individuals came to my clinic, I would have to diagnose them with some kind of cognitive disorder."
Expanding the criteria to 1 standard deviation meant that 40% of participants had subtle impairment. "Patients who are coming in for bariatric surgery are between 5 and 8 times more likely to have cognitive impairment than their normal-weight counterparts. That’s a remarkable number," said Dr. Gunstad.
At 12 weeks, surgery patients who’d lost an average of 48 pounds showed gains in cognitive functioning. Overall, the study showed initial, rapid cognitive improvement, and then either continued or sustained improvement 3 years out.
"We went from a quarter of patients being clinically impaired prior to surgery," said Dr. Gunstad. "At 3 years after surgery, that number was down to 4%."
However, in a related study, Dr. Gunstad and his colleagues found that greater levels of cognitive impairment correlated to less weight loss at all follow-up points (Surg. Obes. Relat. Dis. 2013;9:765-70).
Dr. Gunstad said this was likely due to patient adherence issues after the tumult of bariatric surgery. "You have to eat in a different way. You have to think in a different way. You have to restructure every moment of your life," said Dr. Gunstad. "If you have problems with memory, problem solving, or organizing, it will be much more difficult to make and persist with those changes."
The clinical implication, said Dr. Gunstad, is that better screening of bariatric surgery candidates might be helpful. "If we know the cognitive status of our patients, it’s likely we will know what the outcomes will be," he said.
The drawback, he said, is that even though most third-party payers will cover the costs of evaluations, if a physician has a large practice of hundreds of patients, then the number of referrals might be overwhelming to the system, which might not have enough neuropsychologists to perform the tests.
Self-reporting might also be an issue because of the phenomenon of the "worried well" – the patients who overreport their problems – or because the patients with cognitive impairment won’t necessarily recognize the symptoms they need to report, said Dr. Gunstad.
By next year, said Dr. Gunstad, he hoped he and his colleagues will have finalized a better screening tool for clinicians who treat bariatric surgery patients.
Dr. Gunstad did not report any financial disclosures.