Results The score of time-orientation was worse in SCD group than that in the normal control group [4 (5, 3) vs 5 (5, 4)] significantly (t=3.047, P=0.003). MCI group performed worse than SCD group in calculation, repeat, writing, copying, clock-contour, clock-numbers, clock-hands, digit-backward, tapping, fluency, repeat (MoCA), naming (MoCA) and delayed-recall (MoCA) [2 (3, 1) vs 4 (5, 3); 52 (50.0%) vs 38 (76.0%); 2 (1.9%) vs 10 (20.0%); 13 (12.5%) vs 27 (54.0%); 76 (73.8%) vs 47 (94.0%); 5 (4.9%) vs 25 (50.0%); 4 (3.9%) vs 19 (38.0%); 21 (20.2%) vs 29 (58.0%); 40 (38.5%) vs 43 (86.0%); 37 (35.6%) vs 42 (84.0%); 1 (1.0%) vs 11 (22.0%); 1 (2, 0) vs 2 (3, 2); 0 (1, 0) vs 1 (3, 0)] significantly (t=-5.941, P<0.001; χ2=9.398, P=0.002; χ2=15.357, P<0.001; χ2=30.245, P<0.001; χ2=8.725, P=0.003; χ2=43.521, P<0.001; χ2=30.673, P<0.001; χ2=21.644, P<0.001; χ2=30.169, P<0.001; χ2=31.155, P<0.001; χ2=20.594, P<0.001; t=6.022, P<0.001; t=4.937, P<0.001). In dementia group, the score in time orientation, space orientation, registration, calculation, delayed recall (MMSE), repeat (MMSE), command, tapping and classification-choice-cue were worse than that in MCI group [2 (3, 1) vs 4 (5, 2); 4 (5, 3) vs 5 (5, 5); 2 (3, 1) vs 3 (3, 2); 1 (1, 0) vs 2 (3, 1); 0 (1, 0) vs 2 (2, 0); 2 (3, 1) vs 3 (3, 3); 25 (27.8%) vs 52 (50.0%); 16 (17.8%) vs 40 (38.5%); 0 (1, 0) vs 1 (1, 0)] with significance (t=-7.946, P<0.001; t=-6.012, P<0.001; t=-4.870, P<0.001; t=-6.927, P<0.001; t=-5.456, P<0.001; t=-6.997, P<0.001; χ2=9.954, P=0.002; χ2=9.483, P=0.002; t=2.745, P=0.007).
Conclusion Orientation, registration, calculation, repeat, copying, clock-hands, and tapping showed well discriminant power among groups. Reading, trail, cube, naming (MMSE) were inappropriate for the illiteracy.