Bariatric surgery (BS) is a well-estab­lished treat­ment for obe­si­ty that induces sub­stan­tial and per­ma­nent weight loss. How­ev­er, a sig­nif­i­cant por­tion of patients show lit­tle to no response. Weight loss might be caused by the body’s meta­bol­ic adap­tion to the rearranged diges­tive tract. Also, recent­ly pro­posed changes in the cen­tral ner­vous sys­tem, alter­ing eat­ing and moti­va­tion­al behav­ior, sug­gest a strong link between gut and brain signaling.
While dif­fer­ences in gut-brain-com­mu­ni­ca­tion fol­low­ing BS have been top­ic of recent research inter­est, lit­tle is known about its rela­tion­ship to the high vari­abil­i­ty in patients’ weight loss. Here, we aim to iden­ti­fy dif­fer­ences between patients with good and poor ther­a­py out­comes by con­nect­ing meta­bol­ic to cog­ni­tive and psy­choso­cial explana­to­ry models.
Using a post-hoc design, we test 50 par­tic­i­pants with either high (>70%) or lit­tle (<35%) excess weight loss at least 2 years after either Roux-en-Y-gas­tric bypass or sleeve gas­trec­to­my, only includ­ing adults with­out neu­ro­log­i­cal impair­ment, uncon­trolled dia­betes (HbA1c > 7%) or sub­stance abuse. We use cog­ni­tive tasks that are indi­rect mark­ers of cen­tral dopamin­er­gic func­tion, specif­i­cal­ly test­ing work­ing mem­o­ry, learn­ing behav­ior and impul­siv­i­ty. Release of gut pep­tides and a meta­bol­ic pro­file will be mea­sured via blood sam­ples before and after a 300-kcal stan­dard­ized liq­uid meal. Eat­ing behav­ior, per­son­al­i­ty traits and mood are assessed via stan­dard­ized ques­tion­naires. Enteric micro­bio­ta will be ana­lyzed via shot­gun sequencing.
We expect to find a sig­nif­i­cant group dif­fer­ence between ther­a­peu­tic out­come and inges­tion-relat­ed response of gut pep­tides, psy­choso­cial char­ac­ter­is­tics and cen­tral dopamin­er­gic lev­el as mea­sured by cog­ni­tive function.