The Liver–Gut–Brain Axis and Hepatic Encephalopathy

Hepatic encephalopathy (HE) is one of the severe complications of a broad complex of liver injuries, encircling an extensive range of reversible neurological and psychomotor dysfunctions varying from confusion to coma. Based on the etiology, it is categorized into three main categories: type A (resulting from acute liver failure), type B (with underlying portosystemic shunt), and type C (due to liver cirrhosis). A mortality rate could reach 65% depending on the type analyzed. HE affects patients’ quality of life, and successful treatment starts with detecting the leading cause of precipitating events. It is unclear whether the neurological dysfunction is secondary to the etiology of liver disease or comorbidities. In some cases, it might be challenging to attribute neurological disturbances to a specific factor. This chapter elucidates the role of ammonia, altered microbiota, neuroinflammation, hepatitis viruses, and extracellular vesicles as possible mechanisms contributing to HE development.