Context: The mechanisms by which obesity alters the cerebral function and the effect of weight loss on the brain have not been completely clarified.
Objective: The objective of the study was to assess the effect of bariatric surgery on the cognitive function and cerebral metabolism.
Design: Seventeen obese women were studied prior to and 24 weeks after bariatric surgery using neuropsychological tests and positron emission tomography.
Setting: The study was conducted in a reference center for the treatment of obesity of a Brazilian public university.
Participants: Thirty-three women paired by age and level of education made up two groups: 17 severely obese patients and 16 lean patients. They did not have diabetes mellitus or a family history of dementia.
Main outcome measures: Comparison of performance in neuropsychological tests and cerebral metabolism of the obese women before and after bariatric surgery was measured. The results found at the two moments were compared with those of the women of normal weight.
Results: Women with a mean age of 40.5 years and mean body mass index of 50.1 kg/m(2) when compared with women with mean body mass index of 22.3 kg/m(2) showed increased cerebral metabolism, especially in the posterior cingulate gyrus (P < .004). No difference was found between the groups for the neuropsychological tests. After 24 weeks the cerebral metabolism of the obese women was lower, similar to the lean women, and there was an improvement of executive function, accompanying changes of metabolic and inflammatory parameters.
Conclusions: Obese women may have increased cerebral metabolism when compared with women of normal weight, and this appears to reverse after weight loss induced by bariatric surgery, accompanied by improved executive function.