Adding age, sex, education, and APOEɛ4 allele to plasma NfL in the models significantly improved the accuracy for discriminating AD from non-dementia (AUC = 0.85:95% CI 0.81–0.88), normal cognition (0.87; 0.84–0.91), and MCI (0.79; 0.74–0.83) (compared with plasma NfL alone, all p for bootstrap test <0.001), but not for differentiating between MCI and normal cognition (p for bootstrap test >0.05) (Supplementary Table 1). This evidence concerns the gene NEFL and dementia.