In contrast, the synaptic peptides to NPTX2 (AUC of 74.0%), NPTXR (AUC of 71.1%), VGF (AUC of 70.1%) and SCG2 (AUC of 69.8%) best discriminated AD from AsymAD groups suggesting that neurodegeneration due to AD pathology is occurring in the symptomatic phase of disease44. Here, SCG2 is linked to Alzheimer disease.