In terms of D-galactose-induced mice model, the ameliorating cognitive impairment action of the proanthocyanidins correlated with reverse of oxidative damage, prevention of Aβ overproduction and suppression of NO production, appearing as enhancements of SOD and GPX activities in brain, reductions of Aβ1–42, NO and MDA levels and AchE, MAO-B, tNOS and nNOS activities in brain, and declinations of nerve cell apoptosis and p53 protein expression in hippocampus (12). Here, MAOB is linked to Cognitive impairment.