An exploratory subgroup analysis based on data from studies applying DTI methods only (n = 11), revealed four clusters of convergent microstructural WM alterations (Supplementary Table S5 and Fig. S2). Three clusters cover similar locations as the main analysis and comprise the left fornix, the right body of the corpus callosum with extension to the posterior cingulum bundle, and the right genu of the corpus callosum with extension to the anterior cingulum bundle. In contrast to the main analysis, the peak-coordinates of the studies in this subgroup did not show convergence in the right posterior limb of the internal capsule nor the midbody of the corpus callosum (C3 and parts of C1, see Fig. 1 and S2 for comparison). These clusters were characterized by a substantial proportion of VBM studies (3 of 5 and 3 of 8, respectively) and thus, the remaining DTI studies do not have sufficient weight to reach the significance threshold.
