Exclusion criteria were as follows: 1) study of primary drug of abuse other than alcohol; 2) no AUD group (i.e., study of alcohol effects in the population or moderate drinkers); 3) use of region-of-interest, diffusion tensor imaging (DTI), deformation-based morphometry (DBM), or voxel-based morphometry (VBM) methodology to study WM without reporting or testing of overall or cerebral WM volume. Practically speaking, most studies that used a region-of-interest approach also reported overall WM volume either in the same study or in a separate report on the same sample. The same was not necessarily true of DBM or VBM studies, yet their outcome measures (focal areas of difference reported as coordinates and Z-scores of significant clusters) diverge from global WM volume measures to the extent that combining these types of statistics would be of questionable meaning (see Ashburner and Friston, 2000). See Table 1 for examples of excluded studies.
