NRXN3 and major depressive disorder: With respect to an association with the ratios Aβ42/40 and Aβ42/ptau, we observed differences between the synaptic markers: while SNAP-25 was not associated with the ratios as mentioned above, NRXN3 and NGRN showed a moderate correlation with Aβ42/ptau in the whole cohort and in MDD specifically.