NRGN and Alzheimer disease: CT-Ng significantly correlated with synaptotagmin 215–223 (rho = 0.512, P = 0.04) and synaptotagmin 238–245 (rho = 0.527, P = 0.03) in patients with MCI-AD, while FL-Ng did not correlate with any of the pre-synaptic markers within this group (Table 3).