Background: Growing evidence has shown that obesity is associated with poor neurocognitive outcomes. Bariatric surgery has been shown to be an effective intervention for morbid obesity and can result in improvement of many co-morbid medical conditions that are associated with cognitive dysfunction. The effects of bariatric surgery on cognition are unknown.

Methods: We performed a prospective study total of 150 subjects (109 bariatric surgery patients enrolled in the Longitudinal Assessment of Bariatric Surgery project and 41 obese control subjects who had not undergone bariatric surgery). These 150 subjects completed a cognitive evaluation at baseline and at 12 weeks of follow-up. The demographic, medical, and psychosocial information was also collected to elucidate the possible mechanisms of change.

Results: Many bariatric surgery patients exhibited impaired performance on cognitive testing at baseline (range 4.6-23.9%). However, the surgery patients were no more likely to exhibit a decline on ≥2 cognitive tests at 12 weeks of follow-up than were the obese controls [12.84% versus 23.26%; chi-square (1) = 2.51, P = .11]. Group comparisons using repeated measures multivariate analysis of variance showed that the surgery patients had improved memory performance at 12 weeks of follow-up [λ = .86, F(4, 147) = 5.88, P <.001]; however, the memory performance of the obese controls had actually declined. Regression analyses showed that the surgery patients without hypertension had better short delay recall at 12 weeks than those with hypertension [β = .31, P = .005], although the other demographic and medical variables were largely unrelated to the test performance.

Conclusion: The present results suggest that cognitive impairment is common in bariatric surgery patients, although these deficits might be at least partly reversible. Future studies are needed to clarify the underlying mechanisms, in particular, longitudinal studies using neuroimaging and blood markers.