Results examining lifetime MDD status are consistent with the proposition that current source density-referenced frontal EEG asymmetry is an endophenotype related to risk for depression in both women and men, unconfounded by current symptom severity. Participants with lifetime MDD (both current MDD and past MDD) displayed less relative left frontal activity than never-depressed participants, and measures of current depression (BDI-II and HRSD scales) did not account for this effect. These findings indicate that current source density-referenced EEG asymmetry may be a liability marker, identifying a vulnerability to develop depression (e.g., Allen et al., 2004b, Gotlib et al., 1998; Henriques & Davidson, 1990, 1991) and related dysphoric conditions (Accortt & Allen, 2006; Coan & Allen, 2008), although prospective studies are needed to definitively test this proposition.
