Surprisingly, like CSF SV2A, serum SV2A also demonstrated statistical significance in the diagnosis of aMCI (AUC = 74.1%, 95% CI = 0.674–0.802, sensitivity = 97.80%) (Fig. 2m) and differential diagnosis of aMCI from AD (AUC = 70.2%, 95% CI = 0.642–0.758) (Fig. 2o). Here, SV2A is linked to Alzheimer disease.