Effect of bariatric surgery on neurocognitive function after 6 months of follow-up: a pilot study

Background: reduced cognitive performance has been observed in patients with severe obesity. Bariatric surgery and subsequent adipose tissue loss seem to affect cognitive functioning positively; however, improvement predictors are not well established. Aim: to evaluate the cognitive performance and the nutritional status of patients with severe obesity 6-month after bariatric surgery. Methods: we assessed the neuropsychological performance of 22 patients with obesity (body mass index: ~ 42.9 kg/m²). The nutritional evaluation consisted of the routine tests performed in the baseline and postoperative periods. Lastly, we calculated the correlation between neuropsychological assessment results and blood biomarkers. Results: the patients did not present cognitive impairment in the preoperative assessment, but performed below the standard range. The patients underwent significant weight loss after 6 months from surgery (~ 22 kg), with a change in obesity class III to I. Also, the patients presented a significant improvement in attention, mental flexibility, inhibitory control, and processing speed. Additionally, we observed a significant improvement in serum folic acid (108 %), gamma-glutamyl transferase (-41 %), uric acid (-32 %), ferritin (-28 %), triglycerides (-19 %), and high-density lipoprotein (9 %). Lastly, we found a moderate positive correlation between processing speed and body weight (r = 0.46), gamma-glutamyl transferase (r = 0.54), and total protein and mental flexibility (r = 0.75). Conclusion: bariatric surgery promoted significant weight loss and improved attention, mental flexibility, processing speed, and several nutritional biomarkers. Nevertheless, the surgery had limited effects on other cognitive functions such as short- and long-term memory and language.