Neuroimaging correlates of cognitive changes after bariatric surgery

Abstract

Background: Obesity has been associated with cognitive deficits and increased risk for developing dementia. Bariatric surgery may result in improved cognitive function; however, the underlying structural and functional brain correlates are unclear.

Objectives: This longitudinal study explores the hypothesis that specific brain regions and networks underlie cognitive changes after bariatric surgery.

Setting: University Hospital, United States.

Methods: Seventeen patients were recruited for this prospective cohort study, including 9 patients undergoing bariatric surgery, and 8 age-, sex-, and education level-matched healthy, nonobese control patients. Bariatric patients underwent longitudinal neuropsychologic tests and magnetic resonance imaging (MRI) scans both before and 6 months after surgery. One patient was lost to follow-up. The same neuropsychologic tests and MRI scans were performed for control patients. Differences in MRI and neuropsychologic testing between bariatric patients and control patients, and longitudinal changes within bariatric patients were assessed.

Results: At baseline, bariatric patients demonstrated deficits in cognitive function relative to control patients, including pattern comparison (P = .009) and picture sequence memory (P = .004), which improved after significant weight loss. Baseline cognitive deficits in bariatric patients were accompanied by significantly lower left executive control network connectivity on resting-state functional MRI relative to control patients (P = .028), but differences resolved or diminished after bariatric surgery. Longitudinal improvements in pattern comparison performance correlated significantly with increases in left executive control network connectivity (r = .819; P = .013). No significant group or longitudinal differences were found in brain perfusion or brain white matter lesions.

Conclusions: Individuals with obesity undergoing bariatric surgery exhibit deficits in cognitive function and specific alterations of brain networks; however, cognitive performance can improve, and executive control network connectivity can increase after weight loss from bariatric surgery.

Keywords: Bariatric surgery; Cognitive testing; Obesity; Resting-state functional magnetic resonance imaging.