Chunk #25 — Results — Frontal EEG Asymmetry as a Function of Lifetime DSM-IV-Defined Depression — Follow-up analyses: Current MDD status and depression severity
alpha power was again the dependent variable. If EEG asymmetry results represent trait effects that are not due to current depressive symptomatology, a lifetime MDD effect should still emerge. A main effect emerged for BDI-II (F(1, 303) = 11.0, p = .001), indicating that higher BDI-II scores were associated with relatively less left frontal activity (estimated -1 SD on BDI-II: M = .069 and SE = .01 vs. estimated +1 SD on BDI-II: M = .063, SE = .01, d = .05). A main effect also emerged for HRSD (F(1, 303) = 20.2, p < .001), demonstrating that higher HRSD scores were associated with relatively less left frontal activity (estimated -1 SD on HRSD: M = .077 and SE = .01 vs. estimated +1 SD on HRSD: M = .054, SE = .01, d = .21). Most importantly, however, the main effect of lifetime MDD remained significant when entered after BDI-II (F(1, 303) = 12.7, p < .001, d = .50) or HRSD(F(1, 303) = 18.6, p < .001, d = .43), indicating that relationship of lifetime MDD status to CSD–referenced frontal asymmetry could not be accounted for by current levels of depression symptoms.
