Objective: The study investigated the hypothesis that EEG asymmetry scores (indicating higher right and lower left frontal brain activity) are associated with vulnerability to negative mood states and depressive disorders. Gender and clinical history variables were examined as factors that may influence the relation between EEG and depression.
Method: EEG measures of asymmetrical alpha frequency (7.5-12.5 Hz) suppression were analyzed in 55 young adults with a documented clinical history of childhood-onset depression and 55 comparison subjects with no history of major psychopathology. EEG patterns were examined in relation to operational diagnoses of mental disorders during childhood and adulthood.
Results: Differences in EEG asymmetry between childhood depression probands and comparison subjects varied with gender, diagnostic history, and current symptoms. Women with childhood depression had higher right midfrontal alpha suppression, and men with childhood depression had higher left midfrontal alpha suppression, relative to comparison subjects. At all scalp sites, women showed greater alpha power than men. Probands with a bipolar spectrum course had the most extreme midfrontal asymmetry. Frontal asymmetry was more extreme in probands with current depressive symptoms than in those without current symptoms.
Conclusions: Regional brain activity is influenced by gender and variability in clinical course. The findings have implications for investigating brain correlates of mood disorder and may help to develop more refined phenotypes.