Table 2. Cognitive performance across study groups.
| HC (n = 69) | SMD (n = 86) | MCI (n = 45) | AD (n = 38) | MANOVA/MANCOVA* | Post-hoc ANOVA/ANCOVA |
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|---|---|---|---|---|---|---|---|---|
| Uncorrected p-value | BH corrected p-value | |||||||
| Stroop-colours | M(SD) | 13.8 (3.2) | 14.6 (3.1)a | 16.6 (5.3)a | 25.2 (13.2)a,b,c | Multivariate effect: <0.001 Post-hoc paired tests: HC vs. SMD p = 0.015 *4 HC vs. MCI p < 0.001 HC vs. AD p < 0.001 SMD vs. MCI p < 0.001 SMD vs. AD p < 0.001 MCI vs. AD p = 0.001 *5 | <0.001 | <0.001 |
| Z-score | −0.1 | 0.4 | 0.9 | 3.0 | ||||
| Stroop-words | M(SD) | 18.0 (4.1) | 19.3 (4.9)a*1 | 24.8 (9.0)a,b | 38.4 (20.9)a,b,c | <0.001 | <0.001 | |
| Z-score | −0.1 | 0.4 | 1.3 | 3.1 | ||||
| Stroop-interference | M(SD) | 33.1 (9.2) | 33.9 (11.4) | 47.9 (21.1)a,b | 92.2 (87.6)a,b,c | <0.001 | <0.001 | |
| Z-score | −0.3 | −0.2 | 0.4 | 2.8 | ||||
| Digit Symbol-Coding | M(SD) | 59.8 (13.4) | 55.8 (12.3) | 49.1 (15.5)a,b*2 | 32.1 (14.8)a,b,c | <0.001 | <0.001 | |
| Z-score | 0.6 | 0.3 | 0.1 | −1.1 | ||||
| Digit Span | M(SD) | 18.3 (3.8) | 17.7 (3.8) | 16.4 (3.4)a† | 13.4 (4.3)a,b,c | <0.001 | <0.001 | |
| Z-score | 0.8 | 0.6 | 0.3 | −0.4 | ||||
| CVLT-II Learning | M(SD) | 52.3 (10.9) | 50.2 (10.7) | 31.2 (8.8)a,b | 20.7 (8.7)a,b,c | <0.001 | <0.001 | |
| Z-score | 1.3 | 1.1 | −0.9 | −2.2 | ||||
| CVLT-II Delayed recall | M(SD) | 12.1 (2.9) | 11.3 (3.3) | 4.0 (3.2)a,b | 1.0 (2.0)a,b,c | <0.001 | <0.001 | |
| Z-score | 1.0 | 0.8 | −1.5 | −2.6 | ||||
| CVLT-II Recognition | M(SD) | 14.5 (1.6) | 15.0 (1.5) | 12.7 (2.8)a,b | 11.6 (2.5)a,b,c*3 | <0.001 | <0.001 | |
| Z-score | 0 | 0.3 | −1.0 | −1.8 | ||||
| RCFT Copy | M(SD) | 31.9 (3.0) | 31.2 (3.5) | 27.8 (6.2)a,b | 21.1 (10.7)a,b,c | <0.001 | <0.001 | |
| Z-score | −0.2 | −0.4 | −1.3 | −4.2 | ||||
| RCFT Delayed recall | M(SD) | 17.1 (5.4) | 16.1 (6.0) | 8.9 (5.5)a,b | 2.7 (3.0)a,b,c | <0.001 | <0.001 | |
| Z-score | 1.0 | 0.7 | −0.8 | −2.5 | ||||
| RCFT Recognition | M(SD) | 20.2 (1.9) | 20.4 (2.2) | 18.6 (2.0)a,b | 15.9 (2.6)a,b,c | <0.001 | <0.001 | |
| Z-score | 0.3 | 0.4 | −0.8 | −2.6 | ||||
| BNT | M(SD) | 28.6 (1.6) | 27.8 (2.0)a*1 | 25.1 (4.8)a,b | 20.9 (7.4)a,b,c | <0.001 | <0.001 | |
| Z-score | 0.9 | 0.8 | 0.1 | −1.0 | ||||
| VF-letter | M(SD) | 40.9 (11.8) | 40.4 (12.6) | 33.1 (12.4)a,b | 27.1 (14.5)a,b | <0.001 | <0.001 | |
| Z-score | 0.6 | 0.6 | −0.1 | −0.7 | ||||
| VF-category | M(SD) | 41.7 (8.0) | 36.7 (7.3)a | 31.2 (9.0)a,b | 20.9 (9.2)a,b,c | <0.001 | <0.001 | |
| Z-score | 1.1 | 0.4 | −0.2 | −1.5 | ||||
Performance is measured as time in Stroop and number of correct responses in the other cognitive tests. Z-scores were calculated using age- and education-corrected Australian normative values. aSignificantly different from HC; bsignificantly different from SMD; csignificantly different from MCI. *Results from the MANCOVA are marked with *. *1SMD vs. HC non-significant when controlling for age, gender, education level and HADS-D; *2MCI vs. SMD non-significant when controlling for age, gender, education level and HADS-D; *3AD vs. MCI becomes significant (p = 0.008 after Benjamini-Hochberg’s correction) when controlling for age, gender, education level and HADS-D; *4p = 0.020 after Benjamini-Hochberg’s correction when controlling for age, gender, education level and HADS-D; *5p = 0.002 after Benjamini-Hochberg’s correction; †MCI vs. HC p = 0.055 after Benjamini-Hochberg’s correction. M(SD) = mean (standard deviation); HC = healthy controls; SMD = subjective memory decline; MCI = Mild Cognitive Impairment; AD = Alzheimer’s disease; BH = Benjamini-Hochberg; CVLT-II = California Verbal Learning Test-Second edition; RCFT = Rey Complex Figure Test; BNT = Boston Naming Test; VF = Verbal Fluency.