The liver normally filters out ammonia, which is a toxic by-product from the break down of protein that we eat, but when the liver is too damaged it can't do that anymore, and the ammonia
ends up in
, and goes to your brain, where it causes mental symptoms. That's hepatic encephalopathy, which is a complication of advanced cirrhosis. Lactulose is the standard treatment, it binds to the ammonia in the body and makes it pass through the intestines.