Evoked potential topography in major depression. II. Comparisons between subgroups.

Brief Psychiatric Rating Scale (BPRS) ratings of 69 patients with major depression (MD) were employed in an attempt to define subgroups of MD with more homogeneous evoked potential (EP) findings than the MD group as a whole. Correlations were computed between 6 BPRS ratings and scores for 32 EP factors; 14 correlations were significant. These indicated mainly that EP values were related to severity of depression. When age- and gender-matched groups of MDs with above- and below-median depressive mood (D) ratings were compared with controls, 3 of the 10 factors differing significantly between groups gave evidence of two different subgroups of MD. EPs of these subgroups differed from those of controls in opposite directions. Such bidirectional differences from normal suggest differing pathophysiology in the subgroups and support the multiple process view of depression.