NRGN and Alzheimer disease: Second, it was determined whether quantitative clinical biomarkers of AD pathology (i.e., amyloid beta 42 [Aβ42], Aβ42/40, phosphorylated MAPT/tau (181) (p-MAPT/tau [181]) and total MAPT/tau (t-MAPT/tau) neurodegeneration (NEFL [neurofilament light chain]), synaptic dysfunction (NRGN [neurogranin]), cognitive status and brain atrophy correlated with biomarkers of mitophagy.