Microbiome-Gut-Brain Axis: Implications for the Links Between Inflammatory Bowel Disease and Neuropsychiatric Disorders.

The brain and gastrointestinal tract are closely interconnected as important sensory organs processing signals from both environmental and internal cues. Recent studies have shown that dysregulation of the gut microbiota in inflammatory bowel disease activates the gut immune system. The cross-talk mechanism along the gut-brain axis is implicated in the development of neuropsychiatric disorders such as autism, depression, anxiety, Alzheimer's disease, and Parkinson's disease. Here, we discuss the molecular mechanisms involved in signaling across the gut-brain axis, including the immune and neuroendocrine system, intestinal permeability, microbial composition, and bacterial extracellular vesicles. We focus on the link between specific inflammatory bowel disease, microbial genera and psychiatric and neurological disorders, and propose that the results of preclinical and clinical studies open up the possibility of targeting the gut microbiota to treat neuropsychiatric disorders that are altered by gut interactions.