Table 6.
Path c (total effect of age): b = −0.08, R2 = 0.46, p < 0.001 | ||||||||
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Region | Lat | BA | Size | Change in variance compared with path c (δF(df), δR2, p value) | Parameter estimates |
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Path a | Path b | Path c′ | Indirect effects (b, 95% CI, K2) | |||||
SPL | R | 7 | 356 | δF(1,60) = 15.6, δR2 = 0.11, p < 0.001 | b = −0.22, p < 0.001 | b = 0.13, p < 0.001 | b = −0.06, p < 0.001 | b = −0.03 (−0.05 −0.01) (*) K2 = 0.25 |
Cuneus | L | 19 | 71 | δF(1,60) = 11.7, δR2 = 0.09, p = 0.001 | b = −0.16, p < 0.001 | b = 0.11, p = 0.001 | b = −0.07, p < 0.001 | b = −0.02 (−0.03 −0.01) (*) K2 = 0.17 |
MFG | R | 6 | 68 | δF(1,60) = 11.4, δR2 = 0.09, p = 0.001 | b = −0.33, p < 0.001 | b = 0.11, p = 0.001 | b = −0.05, p = 0.003 | b = −0.04 (−0.06 −0.02) (*) K2 = 0.28 |
Rows illustrate simple mediation models for frontal SW amplitude with mean CT in each region as stand-alone mediators. δF indicates the change in explained variance due to inclusion of the CT cluster as a mediator compared with the total effect model (path c). Coefficients in each path necessary for the computation of indirect effects are shown in designated columns. b-values refer to unstandardized parameters estimates of paths shown in Figure 1. Indirect effects are significant at p < 0.05 when 0 is not included in the 95% CI and significance is denoted with an asterisk. K2 is an effect size of mediation and thus represents the proportion of the age-related effect on frontal SW amplitude that has been mediated by changes in CT (>0.25 = strong effect; >0.09 = medium effect; >0.001 = small effect). CT in each region is adjusted for ICV.