In summary, women and men displayed opposing patterns of frontal EEG asymmetry as a function of current depression severity for the linked mastoid reference (and the pattern of means for the average reference was consistent with the linked-mastoid pattern). Whether these findings signify different mechanisms underlying depression in men and women remains an open question. Although it is possible that these asymmetry findings may reveal different causal pathways, they might also reflect different symptom constellations in depression in men and women (e.g., Kornstein et al., 2000; Silverstein, 2002). For example, pure MDD+ men suffer more sudden spells of anger and aggression than pure MDD+ women (Winkler, Pjrek, & Kasper, 2005), suggesting anger could be a moderator of EEG asymmetry that could explain sex differences in depression, since relatively greater left frontal activity characterizes individuals with trait anger at rest (e.g., Harmon-Jones & Allen, 1998). Additional evidence in support of this argument of anger as a moderator of frontal brain asymmetry are findings demonstrating that boys without oppositional defiant disorder display relatively less left frontal EEG activity, consistent with the EEG
