There is a robust postmortem literature showing that constituents of white matter fiber systems are negatively affected by alcoholism (De la Monte 1988; Harper et al. 2003; Harper et al. 1990) and normal aging (Aboitiz et al. 1996; Dickson et al. 1992; Kemper 1994; Marner et al. 2003; Meier-Ruge et al. 1992) Both alcoholism (Lewohl et al. 2000; Tarnowska-Dziduszko et al. 1995) and aging (Peters 2002) show demyelination. In vivo DTI studies of alcoholism (Rosenbloom et al. 2003; Sullivan and Pfefferbaum 2005) and aging (Salat et al. 2005; Stadlbauer et al. 2008; Sullivan and Pfefferbaum 2006; 2007; Sullivan et al. 2010b) comport with the postmortem findings in demonstrating low FA and high diffusivity, typically λT, a marker of myelin degradation (Song et al. 2003; Song et al. 2002; Song et al. 2005). The relation between low δ power and high λT in cingulate bundles in the present analysis suggests myelin degradation in the long association fiber system of the cingulate bundle as underlying low δ power in alcoholism and older age.
