It was recently reported that the level of neuroligin-1 (Nlgn1), a post-synaptic cell adhesion protein, was reduced in the CSF of patients with AD (n = 43) compared with controls (n = 42) [71], indicating that Nlgn1 is an interesting synaptic biomarker candidate for neurodegenerative diseases. Here, NLGN1 is linked to neurodegenerative disease.