Table 3.
Moderated mediation models examining the mediating effect of IT microglial activation (PAM IT) on the relationship between physical activity and (Model 1, N = 156) global cognitive outcomes or (Model 2, N = 154) synaptic integrity markers in the IT gyrus
| Effect | SE | p | 95% CI | |
|---|---|---|---|---|
| Moderation effect (physical activity × AD pathology → PAM IT) | ||||
| Age | 0.0005 | 0.0008 | 0.49 | −0.001, 0.002 |
| Sex | −0.015 | 0.009 | 0.11 | −0.032, 0.033 |
| Education | 0.0017 | 0.0017 | 0.32 | −0.0017, 0.005 |
| motor10 | −0.026 | 0.030 | 0.39 | −0.085, 0.033 |
| AD pathology | 0.076 | 0.016 | <0.001 | 0.045, 0.011 |
| Physical activity | 0.001 | 0.006 | 0.89 | −0.011, 0.012 |
| Physical activity × AD | −0.016 | 0.007 | 0.014 | −0.029, −0.003 |
| Model 1: Direct effect (physical activity → cognition) | ||||
| Age | 0.005 | 0.0012 | <0.001 | 0.002, 0.007 |
| Sex | −0.024 | 0.015 | 0.11 | −0.052, 0.005 |
| Education | −0.002 | 0.003 | 0.54 | −0.007, 0.004 |
| motor10 | 0.089 | 0.048 | 0.065 | −0.006, 0.184 |
| PAM IT | −0.50 | 0.12 | <0.001 | −0.734, −0.267 |
| Physical activity | 0.017 | 0.007 | 0.011 | 0.004, 0.030 |
| Model 1: Conditional indirect effects (physical activity → PAM IT → cognition, at levels of AD pathology) | ||||
| Index of moderated mediation | Index: 0.008 | 0.005 | — | 0.002, 0.019 |
| AD pathology | — | |||
| Low (16th percentile) | 0.002 | 0.003 | −0.005, 0.006 | |
| Medium (50th percentile) | 0.004 | 0.003 | 0.002, 0.01 | |
| High (84th percentile) | 0.011 | 0.005 | 0.003, 0.023 | |
| Model 2: Direct effect (physical activity → synapse IT) | ||||
| Age | 0.026 | 0.014 | 0.055 | −0.005, 0.053 |
| Sex | −0.032 | 0.161 | 0.84 | −0.351, 0.287 |
| Education | 0.012 | 0.030 | 0.69 | −0.047, 0.072 |
| motor10 | −0.036 | 0.53 | 0.95 | −1.084, 1.012 |
| PAM IT | −3.573 | 1.34 | 0.008 | −6.22, −0.928 |
| Physical activity | 0.105 | 0.073 | 0.154 | −0.040, 0.249 |
| Model 2: Conditional indirect effects (physical activity → PAM IT → synapse IT, at levels of AD pathology) | ||||
| Index of moderated mediation | Index: 0.057 | 0.033 | — | 0.007, 0.135 |
| AD pathology | — | |||
| Low (16th percentile) | 0.002 | 0.020 | −0.038, 0.042 | |
| Medium (50th percentile) | 0.029 | 0.018 | 0.001, 0.070 | |
| High (84th percentile) | 0.076 | 0.037 | 0.016, 0.161 |
Both models estimated indirect effects of PAM IT (mediation) conditional on AD pathology burden (moderation) using 5000-sample bootstrapping. 16th percentile roughly corresponds to −1 SD, and 84th percentile roughly corresponds to 1 SD.