Neuroinflammatory remodeling of the anterior cingulate cortex as a key driver of mood disorders in gastrointestinal disease and disorders.

Most gastrointestinal diseases and disorders (GIDD) are associated with depression, anxiety, and cognitive dysfunction. This suggests that shared features of GIDD, particularly chronic pain and inflammation, affect specific neural targets. The critical review of clinical and animal research presented here reveals that anterior cingulate cortex (ACC) is a primary target. It is particularly sensitive to neuroinflammation, and its function accounts for altered mental function emergent in GIDD. We propose that peripherally-triggered neuroinflammation normally signals injury/illness to ACC, which increases threat assessment and pain sensitivity to cope with increased vulnerability. Chronic peripheral inflammation over-drives this process, leading to long-term ACC structural remodeling, and excessive threat signaling. This evokes anxiodepressive phenotypes even without direct evidence of threats because ACC utilizes schemas to infer affective outcomes (e.g. pain) based on complex contextual information. This activates the autonomic nervous system, exacerbates immune dysfunction, and promotes further gut pathology. This theory provides a mechanistic account of bidirectional interactions among gastrointestinal, immunological, and neural systems in GIDD, and is likely applicable to other chronic inflammatory conditions.