Electroencephalographic measures of regional hemispheric activity in offspring at risk for depressive disorders

Background Electroencephalographic (EEG) studies have found abnormal regional hemispheric asymmetries in depressive disorders, which have been hypothesized to be vulnerability markers for depression. In a longitudinal high-risk study, resting EEG was measured in primarily adult offspring of depressed or nondepressed probands. Methods Electroencephalograms from12 homologous sites over each hemisphere (digitally linked-ears reference) were analyzed in right-handed offspring for whom both parents (n = 18), one parent (n = 40), or neither parent (n = 29) had a major depressive disorder (MDD). Results Offspring with both parents having MDD showed greater alpha asymmetry at medial sites, with relatively less activity (more alpha) over right central and parietal regions, compared with offspring having one or no parent with MDD. Relatively less left frontal activity at lateral sites was associated with lifetime MDD in offspring but not with parental MDD. Offspring with both parents having a MDD also showed markedly greater anterior-to- posterior increase in alpha with eyes closed compared with those with one or no parent with a MDD. Conclusions Alpha asymmetry indicative of right parietotemporal hypoactivity, previously reported for depressed adolescents and adults, and heightened anterior-to-posterior gradient of alpha are present in high-risk offspring having parents concordant for MDD.