Long-term stability of frontal electroencephalographic asymmetry in adults with a history of depression and controls.

We investigated the stability in resting EEG across a 1- to 3-year interval in 49 adults (33 female and 16 male) with a history of unipolar depression (first onset prior to the age of 14) and 50 controls (33 female and 17 male) with no history of major psychopathology. Current depressive symptoms were quantified by self-report at both assessments. For the entire sample, EEG asymmetry in the alpha range was moderately stable (intraclass correlations between 0.39 and 0.61). Sex, history of depression, depressive symptom severity at Time 2, and change in symptom severity between Time 1 and Time 2 were unrelated to stability of EEG asymmetry. These findings support the view that resting frontal EEG asymmetry reflects a moderately stable individual difference in adults, irrespective of sex and history of depression.