GP9 and Alzheimer disease: Diagnostic model including GP8, GP9, and GP14 was of promising capability to distinguish dementia from NC group with an AUC of 0.876 (95% CI: 0.815–0.923) and distinguish AD from NC group with an AUC of 0.887 (95% CI: 0.819–0.936) under 5-fold cross-validation random forest classifiers.