MAPT and Alzheimer disease: NPTX2 is a marker of glutamatergic synaptic plasticity,64 which has been shown to be down-regulated in AD correlating with cognitive deterioration and hippocampal volume.65 Here, we used NPTX2/T-tau ratio as it has been shown to have a high classification accuracy in discriminating AD from normal controls and a strong correlation with cognition.47