NRGN and Alzheimer disease: Apart from above mentioned biomarkers, many other pathological changes involved in AD such as oxidative stress, mitochondria dysfunction, axonal degeneration (neurofilament light and total-tau), synaptic degeneration (neurogranin), glial activation, and protein dysfunction can be measured and developed as clinical biomarker (Mantzavinos and Alexiou, 2017; Lashley et al., 2018).