Chunk #24 — Results — Frontal EEG Asymmetry as a Function of Lifetime DSM-IV-Defined Depression — Follow-up analyses: Current MDD status and depression severity
The second approach utilized continuous measures of depression severity. The between-group analysis above necessarily resulted in reduced sample sizes per cell, and additionally those diagnosed with past MDD still had some level of depressive symptoms, so continuous measures of symptomatology (as indexed by BDI-II and HRSD) were utilized to assess whether current severity was responsible for the lifetime MDD effects observed in the CSD referenced-data. Hierarchical linear mixed models using Type 1 (rather than Type 3) sums of squares were used to examine whether significant lifetime MDD results could be accounted for by depressive symptoms measured dimensionally in a model that included either BDI-II or HRSD scores as a main effect. Session day and channel were entered first, followed by BDI-II or HRSD (z-scored), then lifetime MDD was added to the model. EEG asymmetry score based on total 8-13 Hz 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
