Second, TRH and its analogs are able to increase cerebral blood flow and metabolism which often decline with aging and in PD or AD (Farkas et al., 2000; Borghammer et al., 2010; Austin et al., 2011), thus achieve the protection by accelerating the elimination of toxins in the CNS and reducing the formation of anoxia or toxins-induced acidic micro-environment, which is a trigger in AEP activation. This evidence concerns the gene TRH and Alzheimer disease.