One study confirmed direct evidence that liver failure leads to an imbalance in the brain cholinergic system by detecting changes in acetylcholinesterase (AChE) activity in brain tissue in an animal model (Garcia-Ayllon et al., 2008), but no meaningful conclusion has been reached regarding whether butyrylcholinesterase (BuChE) participates in the development of MHE-related liver damage and cognitive impairment. This evidence concerns the gene ACHE and liver failure.