EEG in alcoholics also reveals an increased interhemispheric coherence when compared to unaffected individuals (Kaplan et al., 1985; Michael et al., 1993). Bilateral intrahemispheric coherences in alpha and beta frequency bands were increased in both long-term abstinent and non-abstinent alcoholics compared to controls (Winterer et al., 2003a). These findings were strongest for the high alpha (10.5–12 Hz) frequency band, and were most pronounced at temporal, parietal, and occipital regions, particularly when depressiveness was included as a covariate; there was no effect of length of abstinence on these findings.
