The functional significance of WM reductions in AUDs, their reversal with sustained abstinence, and their ability to account for variance in AUD outcomes are issues of pressing importance. In a study of participants included in 2 studies above (Pfefferbaum et al., 1992; Pfefferbaum et al., 1995), increase in posterior WM volume was significantly correlated with recovery of memory function after several months of abstinence (Sullivan et al., 2000). A naturalistic longitudinal study found that processing speed, which relies heavily on intact WM (Filley, 2001), and a metabolic marker of neuronal integrity in frontal lobe WM were significant predictors of drinking outcomes following AUD treatment (Durazzo et al., 2008). In a DBM study of an overlapping sample, volumes of bilateral orbitofrontal cortex and surrounding WM at baseline were significantly smaller in those who relapsed than those who abstained during the year following treatment (Cardenas et al., 2011). In a DTI study, frontal WM integrity at baseline differed significantly between those who resumed heavy drinking and those who sustained treatment gains at 6-month follow-up (Sorg et al., 2011). These findings suggest that baseline differences in WM health, particularly in frontal lobes, constitute an important individual difference with potential treatment implications.
