magnitude, and moderators of WM reduction are complex and poorly understood. Given the broad functional significance of WM, characterizing the extent of atrophy is key to understanding the pathophysiology of AUDs. By combining effect sizes (ES) from MRI studies comparing AUD and control groups, this meta-analysis sought to provide a reliable estimate of WM volume reduction associated with AUD diagnosis. Factors that might systematically influence outcomes, such as methodological and design characteristics, were examined as moderators of ES distribution. The two main categories of moderators were those of broad importance to research and those specific to the study of AUDs. The former included year of publication, sample size, funding source, affiliation with Veterans Affairs (VA), and MRI methods. AUD-specific moderators were participant age, duration of AUD, lifetime consumption of alcohol, length of abstinence, and treatment-seeking status. In addition, group differences in education were considered as a proxy for socioeconomic differences. Rationale for selection of these variables is briefly discussed, followed by the methods and results of the meta-analysis. Longitudinal studies of WM volume were too few in number for meta-analysis but are reviewed in Supplementary Information.
