Liver cirrhosis results from long-term continuous damage to the liver leading to irreversible buildup of scar tissue impairing liver function. Cirrhosis can occur as a consequence of various chronic liver diseases including alcoholic liver disease and non-alcoholic fatty liver disease. One of the most serious complications of cirrhosis is hepatic encephalopathy (HE), a pathological state characterized by neurological deficits that significantly impair quality of life and overall prognosis. Furthermore, these neurological impairments can be irreversible, persisting after resolution of liver injury. Our current understanding of the events leading to the development of HE is limited, resulting in limited therapeutic options which ultimately leads to poor patient outcomes and generates significant challenges for the US healthcare system. We have recently demonstrated that cholesterol accumulation plays a role in the development of HE due to acute liver failure. However, whether a similar phenomenon can be observed during liver cirrhosis is unknown. The objective of this proposal is to assess the dysregulation in brain cholesterol homeostasis, and the subsequent effects of aberrant neurosteroid synthesis, during HE in models of liver cirrhosis. Based upon strong preliminary data, we propose the novel central hypothesis that during liver cirrhosis there is an accumulation of free and membrane-bound cholesterol in the brain during HE, due to a dysregulation of pathways involved in cholesterol clearance. The excess cholesterol increases neurosteroid synthesis, which depresses neural activity and contributes to the pathogenesis of HE. Three specific aims have been designed to test this working hypothesis: 1) Cholesterol accumulation in the brain contributes to the neurological deficits associated with HE; 2) HE-associated suppresses of cholesterol clearance pathways in the brain is regulated by farnesoid X receptor signaling; 3) Increased brain cholesterol is associated with an aberrant increase in neurosteroid synthesis pathways. With the completion of the proposed studies, we will understand the molecular pathology contributing to the progression of HE in the context of liver cirrhosis. This knowledge will lead to novel therapeutic targets for drug development. This would greatly benefit the US healthcare system by decreasing patient morbidity and mortality, improving patient quality of life, and reducing medical expenditures.