PPIB and neurodegenerative disease: In animal model studies of neurodegenerative diseases, the hallmark role of 3-HB acid in reducing some characteristic symptoms has been well described, for example, preventing the accumulation of β-amyloid peptide, responsible of inflammation and oxidative stress in Alzheimer’s patients [61]; preventing the loss of dopaminergic neurons in the substantia nigra in Parkinson’s [62,63]; and improving the abnormalities in mitochondrial function and microglia overactivation in the brain in Huntington’s disorder [64,65].