Is resting anterior EEG alpha asymmetry a trait marker for depression?

Evidence suggest that asymmetric anterior brain activation is related to af fective style, linking left hemisphere activation to positive affect and ri ght hemisphere activation to negative affect. However, previous reports of left frontal hypoactivation in depressed patients were not confirmed in rec ent studies. This study evaluated additional characteristics of resting EEG alpha (8-13 Hz) asymmetry in 15 clinically depressed patients and 22 healt hy adults by recording EEG activity on two separate occasions, 2-4 weeks ap art. Across both sessions, group differences in anterior EEG asymmetry were compatible with the original hypothesis, However, groups differed in tempo ral stability of anterior EEG asymmetry, which was retest reliable in contr ols but not depressed patients. In contrast, temporal stability of posterio r EEG asymmetry was acceptable in both groups, Increased variability of ant erior EEG asymmetry may be a characteristic feature for depression, and, if so, this would challenge the notion that anterior EEG alpha asymmetry is a trait marker for depression. Copyright (C) 2000 S. Karger AG, Basel.