APOE and Alzheimer disease: Applying the Naïve Bayes simple machine learning approach to a test set, they found that the average time of conversion of MCI to AD was approximately 1 year where a combination of 10 plasma proteins (TTR, CLU, cystatin C, A1AcidG, ICAM-1, CC4, pigment epithelium-derived factor, A1AT, RANTES, and ApoC3) coupled with the APOE ε4 genotype yielded the greatest predictive potential with 85% sensitivity, 88% specificity, 0.87% accuracy, and 68.8/95% PPV/NPV (Table 3).