When APOE ε4 carrier status and SCD-Q9 scores together were added to the model, the AUC increased to 0.747 for NC and OCI groups, and 0.593 for SCDs and OCI groups, suggesting that the predictive power of APOE ε4 is limited, especially when OCI group was split into MCI and dementia groups, their discriminating powers for MCI and NC were marginal, but could be increased by combining with scores of SCD-Q9. This evidence concerns the gene APOE and dementia.