MCI patients had the highest blood KLK‐8 levels (1139.3 pg/mL), compared to AD (453.9 pg/mL) and controls (227 pg/mL), indicating blood KLK‐8 as a stronger discriminator for MCI (AUC = 0.94) than AD (AUC = 0.83)87 and is not associated with non‐amnestic MCI (naMCI).88 Here, KLK8 is linked to Alzheimer disease.