Finally, multiple studies have suggested that TRH acted as a regulator of homeostasis (Gary et al., 2003) involving immune and endocrine system, whereas imbalance of inflammation (Zheng et al., 2016) or diabetes (Arvanitakis et al., 2004) plays a recognized role in neurodegenerative diseases like PD or AD. This evidence concerns the gene TRH and Alzheimer disease.