SV2A and Alzheimer disease: However, the mean level of serum SV2A, consistent with the trend in the CSF, was significantly lower in the AD group than in the VaD and PDD groups (Table 1), with good diagnostic efficacy in identifying AD from VaD (AUC = 82.3%, 95% CI = 0.764–0.872) (Fig. 2p) and PDD (AUC = 84.8%, 95% CI = 0.790–0.895) (Fig. 2q).