Exploring the link between inflammation and brain function after metabolic-bariatric surgery: A year-long fMRI study.

Background: Metabolic-bariatric surgery (MBS) transcends weight loss and offers wide-ranging health benefits, including positive effects on brain function. However, the mechanisms behind these effects remain unclear, particularly in the context of significant postoperative changes in the inflammatory profile characteristic of MBS. Understanding how inflammation influences postoperative brain function can enhance our decision-making on patient eligibility for MBS and create new opportunities to improve the outcomes of this popular treatment.

Objective: To identify brain regions where spontaneous neural activity and functional connectivity are linked with the evolving inflammatory profile following MBS.

Methods: We investigated the relationship between the perioperative ratio of interleukin (IL)-6 to IL-10 and both the amplitude of low-frequency fluctuation (ALFF) and functional connectivity across 375 brain regions. We examined 36 patients at three time points: 1 week before, and 3 and 12 months after laparoscopic sleeve gastrectomy.

Results: Initially, the IL-6/IL-10 ratio increased during the early postoperative period but then decreased to levels lower than the preoperative values 1 year after surgery. We observed that ALFF in four subcortical structures decreased with a rising IL-6/IL-10 ratio and increased with a declining ratio. Conversely, 16 cortical regions displayed the opposite trend. Additionally, functional connectivity between the left insula and bilateral medial prefrontal cortex increased with a rising IL-6/IL-10 ratio and decreased with a declining ratio.

Conclusions: Our study is the first to identify brain regions significantly linked to inflammation after MBS. Importantly, many of the discovered areas were previously shown to be involved in the pathogenesis of obesity or are targets of contemporary medical treatments. Consequently, our findings offer valuable insights for future obesity research, especially in the context of potential therapeutic opportunities.