The bidirectional network consists of neural, endocrine, and immunological signaling pathways and metabolic processes. The gut microbiome —including the microbiota and its metabolites, such as short-chain fatty acids, bile acids, and tryptophan metabolites—plays a central role.
In addition to gastrointestinal diseases—such asCrohn’s disease and irritable bowel syndrome—several neurodegenerative diseases, such as Alzheimer’s disease or Parkinson’s disease, Parkinson’s disease, as well as psychiatric disorders such as depression, and metabolic disorders such as diabetes mellitus, metabolic syndrome, or obesity, have been described in cases where concomitant gutdysbiosis is present.