EEG alpha has found extensive use as an index of relative cortical deactivation (i.e., greater alpha, less activation) in studies of depressive disorders. In early studies, patients having a depressive disorder and elderly adults having a prior depressive disorder showed greater EEG alpha power than healthy controls (10–11). A number of additional studies have reported abnormal regional hemispheric asymmetries of alpha in individuals having a depressive disorder, with relatively less activity in left frontal (12–15) and right parietal regions (16–19).
