NRGN and Alzheimer disease: The synaptic proteins cerebrospinal fluid (CSF) neurogranin (Ng) and synaptosomal-associated protein 25 (SNAP-25) have been most extensively studied; their concentrations are higher in AD compared with control subjects, and higher levels correlate with faster disease progression.10 - 17 Other synaptic proteins are also emerging as potential biomarkers for AD.