NRGN and Alzheimer disease: In this context, recent years have witnessed the rise of a new generation of biomarkers related to AD pathological mechanisms, such as neurofilament light (NFL) for neuronal injury, neurogranin, BACE1, SNAP-25 and synaptotagmin for synaptic dysfunction and/or loss, and sTREM2 and YKL-40 for neuroinflammation, due to the activation of microglia and astrocytes [38,60,61].