CD81 and Alzheimer disease: NDEV levels of NRGN and REST exhibited a similar pattern of decreased levels in mild-to-moderate AD patients (NRGN CD81-adjusted levels: 233.23 pg/ml; REST CD81-adjusted levels: 367.93 pg/ml) compared with controls (p < 0.001 and p < 0.05, respectively) and advanced AD (p < 0.01 both) (Fig. 1e,f).