MAPT and Alzheimer disease: Crosstalk between the brain and periphery is crucial for shaping neuronal survival and function, yet the etiological relevance of bi-directional interactions between neuroendocrine, neuroimmune, and bioenergetic systems, and amyloid and tau pathways for AD progression is unknown (Engelhart et al., 2004; Blennow, 2010; Chakrabarty et al., 2015; Zheng et al., 2015; Alam et al., 2016; Gonzalez et al., 2017).