Table 2.
Cognitive performances according to the cognitive level and duration of education
| Years of education | PD-N (n = 255) | PD-MCI (n = 161) | PD-D (n = 78) | p value | Group comparison |
|---|---|---|---|---|---|
| MMSE | 27.0 ± 2.5 | 23.9 ± 4.0 | 18.5 ± 4.5 | < 0.001 | PD-N > PD-MCI > PD-D |
| Illiteracy | 20.3 ± 3.7 | 15.5 ± 2.9 | 12.8 ± 2.4 | 0.001 | PD-N > PD-MCI = PD-D |
| 0.5–3 | 25.6 ± 2.5 | 21.8 ± 3.2 | 15.6 ± 3.3 | < 0.001 | PD-N > PD-MCI > PD-D |
| 4–6 | 26.5 ± 2.3 | 24.1 ± 2.5 | 18.4 ± 4.6 | < 0.001 | PD-N > PD-MCI > PD-D |
| 7–9 | 26.9 ± 2.1 | 25.4 ± 2.7 | 20.6 ± 2.9 | < 0.001 | PD-N > PD-MCI > PD-D |
| ≥ 10 | 28.1 ± 1.4 | 26.3 ± 2.0 | 20.1 ± 4.3 | < 0.001 | PD-N > PD-MCI > PD-D |
| MoCA | 23.2 ± 4.4 | 18.6 ± 5.4 | 12.1 ± 5.2 | < 0.001 | PD-N > PD-MCI > PD-D |
| Illiteracy | 12.1 ± 1.9 | 8.4 ± 3.8 | 5.0 ± 2.3 | 0.002 | PD-N > PD-MCI > PD-D |
| 0.5–3 | 20.1 ± 4.0 | 14.9 ± 3.7 | 9.1 ± 3.8 | < 0.001 | PD-N > PD-MCI > PD-D |
| 4–6 | 21.5 ± 4.3 | 18.5 ± 3.5 | 11.9 ± 4.9 | < 0.001 | PD-N > PD-MCI > PD-D |
| 7–9 | 23.0 ± 3.1 | 19.9 ± 3.7 | 13.9 ± 4.4 | < 0.001 | PD-N > PD-MCI > PD-D |
| ≥ 10 | 25.6 ± 3.0 | 22.5 ± 3.2 | 14.2 ± 4.9 | < 0.001 | PD-N > PD-MCI > PD-D |
| Attention domain* | 0.23 ± 0.94 | -0.26 ± 0.88 | -0.75 ± 0.88 | < 0.001 | PD-N > PD-MCI > PD-D |
| Illiteracy | -0.02 ± 0.61 | -0.30 ± 0.57 | -0.66 ± 0.63 | 0.222 | PD-N = PD-MCI = PD-D |
| 0.5–3 | 0.25 ± 1.28 | -0.30 ± 0.92 | -0.71 ± 0.66 | 0.030 | PD-N > PD-D |
| 4–6 | 0.10 ± 0.75 | -0.18 ± 0.86 | -0.53 ± 0.79 | 0.025 | PD-N > PD-D |
| 7–9 | 0.17 ± 0.67 | -0.36 ± 0.85 | -0.53 ± 0.49 | 0.001 | PD-N > PD-MCI = PD-D |
| ≥ 10 | 0.55 ± 0.72 | -0.12 ± 0.61 | -0.81 ± 0.74 | < 0.001 | PD-N > PD-MCI > PD-D |
| Language function* | 0.17 ± 0.71 | -0.87 ± 0.77 | -1.70 ± 1.03 | < 0.001 | PD-N > PD-MCI > PD-D |
| Illiteracy | -0.31 ± 0.90 | -0.84 ± 0.64 | -1.79 ± 0.53 | 0.01 | PD-N > PD-D |
| 0.5–3 | -0.18 ± 0.72 | -1.28 ± 0.82 | -1.84 ± 0.78 | < 0.001 | PD-N > PD-MCI = PD-D |
| 4–6 | -0.03 ± 0.54 | -0.88 ± 0.73 | -1.67 ± 1.00 | < 0.001 | PD-N > PD-MCI > PD-D |
| 7–9 | 0.18 ± 0.66 | -0.86 ± 0.75 | -0.81 ± 0.90 | < 0.001 | PD-N > PD-MCI = PD-D |
| ≥ 10 | 0.35 ± 0.72 | -0.65 ± 0.74 | -1.90 ± 1.13 | < 0.001 | PD-N > PD-MCI > PD-D |
| Visuospatial function* | 0.12 ± 0.78 | -1.37 ± 1.69 | -3.72 ± 2.84 | < 0.001 | PD-N > PD-MCI > PD-D |
| Illiteracy | -0.39 ± 0.55 | -0.81 ± 1.00 | -1.91 ± 1.07 | 0.035 | PD-N > PD-D |
| 0.5–3 | -0.08 ± 0.92 | -1.73 ± 0.96 | -2.31 ± 1.48 | < 0.001 | PD-N > PD-MCI = PD-D |
| 4–6 | 0.11 ± 0.79 | -1.35 ± 1.50 | -2.84 ± 1.62 | < 0.001 | PD-N > PD-MCI > PD-D |
| 7–9 | 0.21 ± 0.74 | -1.00 ± 2.01 | -3.42 ± 2.64 | < 0.001 | PD-N > PD-MCI > PD-D |
| ≥ 10 | 0.16 ± 0.77 | -1.46 ± 2.00 | -4.88 ± 3.41 | < 0.001 | PD-N > PD-MCI > PD-D |
| Memory* | -0.03 ± 0.76 | -1.07 ± 0.77 | -1.76 ± 0.61 | < 0.001 | PD-N > PD-MCI > PD-D |
| Illiteracy | -0.48 ± 0.54 | -0.57 ± 0.70 | -0.84 ± 0.13 | 0.6 | PD-N = PD-MCI = PD-D |
| 0.5–3 | -0.23 ± 0.92 | -0.87 ± 0.68 | -1.36 ± 0.51 | < 0.001 | PD-N > PD-MCI = PD-D |
| 4–6 | 0.13 ± 0.72 | -0.88 ± 0.88 | -1.61 ± 0.38 | < 0.001 | PD-N > PD-MCI > PD-D |
| 7–9 | -0.13 ± 0.78 | -1.33 ± 0.64 | -1.65 ± 0.41 | < 0.001 | PD-N > PD-MCI = PD-D |
| ≥ 10 | -0.07 ± 0.72 | -1.28 ± 0.69 | -2.13 ± 0.56 | < 0.001 | PD-N > PD-MCI > PD-D |
| Executive function* | 0.02 ± 1.04 | -0.66 ± 0.95 | -1.73 ± 0.83 | < 0.001 | PD-N > PD-MCI > PD-D |
| Illiteracy | 0.07 ± 0.92 | -0.87 ± 0.88 | -2.30 ± 0.34 | 0.001 | PD-N = PD-MCI > PD-D |
| 0.5–3 | 0.48 ± 1.31 | -0.48 ± 1.01 | -1.07 ± 0.76 | < 0.001 | PD-N > PD-MCI = PD-D |
| 4–6 | -0.22 ± 1.14 | -0.65 ± 1.13 | -1.55 ± 0.97 | 0.001 | PD-N = PD-MCI > PD-D |
| 7–9 | -0.04 ± 0.93 | -0.63 ± 0.87 | -1.41 ± 0.74 | < 0.001 | PD-N > PD-MCI = PD-D |
| ≥ 10 | 0.04 ± 0.97 | -0.70 ± 0.86 | -2.05 ± 0.65 | < 0.001 | PD-N > PD-MCI > PD-D |
*
z score.
PD-N: Parkinson’s disease with normal cognition, PD-MCI: Parkinson’s disease with mild cognitive impairment, PD-D: Parkinson’s disease with dementia, MMSE: Mini-Mental State Examination, MoCA: Montreal Cognitive Assessment.