Statistical table
| Line | Data/dependent variable | Type of test | Statistic | Confidence |
|---|---|---|---|---|
| Methods: performance subgroups | ||||
| a | Hits – false alarms baseline (manipulation–maintenance) | t-test | t = 0.50; DoF = 98 | p = 0.62; CI = –0.30/0.50 |
| b | Hits – false alarms follow-up (manipulation–maintenance) | t-test | t = –10.42; DoF = 98 | p < 0.001; CI = –2.57/–1.75 |
| c | Baseline age (years) | t-test | t = 0.28; DoF = 98 | p = 0.78; CI = –2.12/2.81 |
| d | Education | t-test | t = –0.65; DoF = 98 | p = 0.52; CI = –2.73/1.40 |
| e | Sum of correct responses n-back, baseline | t-test | t = –0.79; DoF = 98 | p = 0.43; CI = –2.31/0.99 |
| f | Sum of correct responses n-back, follow-up | t-test | t = –2.01; DoF = 98 | p = 0.05; CI = –2.94/–0.02 |
| Results: FMRI second level voxelwise analyses using SPM12 | ||||
| g1 | Contrast values, maintenance–control | Multiple regression at baseline (cross-sectional age effect) | p > 0.0001, no significant clusters | |
| g2 | Paired t-test, baseline to follow-up (longitudinal effect) | t = 5.21; DoF = 135 | p = 0.006corrected | |
| g3 | Multiple regression (time × age) | No significant clusters | ||
| g4 | t-test (dropout vs. returners) | t = 4.65 | p < 0.03corrected | |
| h1 | Contrast values, manipulation–control | Multiple regression at baseline (cross-sectional age effect) | p > 0.0001, no significant clusters | |
| h2 | Paired t-test, baseline to follow-up (longitudinal effect) | t = 5.11 DoF = 135 | p = 0.009corrected | |
| h3 | Multiple regression (time × age) | No significant clusters | ||
| h4 | t-test (dropout vs. returners) | t > 3.13 | P < 0.001uncorrected | |
| i1 | Contrast values, manipulation–maintenance | Multiple regression at baseline (cross-sectional age effect) | p > 0.0001, no significant clusters | |
| i2 | Paired t-test, baseline to follow-up (longitudinal effect) | cf. Table 1 | ||
| i3 | Multiple regression (time × age) | No significant clusters | ||
| j | Contrast values, (1) maintenance–control; (2) manipulation–control | Conjunction | cf. Table 1 | |
| Results: post hoc/individual difference analyses | ||||
| k | Right and left parietal β (maintenance–control, follow-up – baseline) | Pearson’s correlation | r = 0.83; DoF = 136 | p < 0.01; CI = 0.58/0.92 |
| l | Right and left parietal β (manipulation–control, follow-up – baseline) | Pearson’s correlation | r = 0.68; DoF = 136 | p < 0.01; CI = 0.35/0.85 |
| m | DLPFC β (manipulation–control) | Paired t-test | t = 2.50; DoF = 135 | p = 0.01; CI = 0.02/0.19 |
| n | DLPFC β (maintenance–control) | Paired t-test | t = 0.97; DoF = 135 | p = 0.33; CI = –0.11/0.04 |
| o | DLPFC β (manipulation–maintenance, follow-up – baseline), bilateral parietal beta (average manipulation and maintenance, follow-up – baseline) | Pearson’s correlation | r = 0.11; DoF = 136 | p = 0.20; CI = –0.06/0.29 |
| p | Performance (hits – false alarms) by condition | Two-way ANOVA | F = 4.82; DoF = 135 | p = 0.03; partial η2 = 0.03 |
| q | DLPFC β (manipulation–maintenance) | Three-way ANOVA | F = 5.63; DoF = 98 | p = 0.02; partial η2 = 0.05 |
| r | Paired t-test | t = 3.09; DoF = 49 | p < 0.01; CI = 0.08/0.36 | |
| s | Paired t-test | t = 0.54; DoF = 49 | p = 0.59; CI = –0.07/0.13 | |
| t | Bilateral parietal β (maintenance–control, baseline) | t-test | t = –3.59; DoF = 215 | p < 0.01; CI = –0.21/–0.03 |
| u | Bilateral parietal β (manipulation–control, baseline) | t-test | t = –2.70; DoF = 215 | p = 0.01; CI = –0.19/–0.03 |
| v | Outcome: dropout (yes/no) | Logistic regression | cf. Table 3 | |