Modulation of Evoked Brain Responses to Biologically and Socially Important Stimuli in Women with Recurrent Depression

Abstract

Study Objective: To study characteristic features of brain activity in women with recurrent depression (RD) using the tasks with emotional stimuli possessing biological or social importance. Study Design: Controlled randomized experimental trial. Materials and Methods. There were two groups: 42 patients with RD and 72 healthy women. Patients did not take medications before electroencephalogram (EEG) recording. The task was to differentiate between people and animals at 160 pictures: 80 pictures were neutral, and 80 pictures depicted angry/aggressive people or animals. Simple figures (clues) were demonstrated 2s before pictures, and no association was explained. A 128-channel EEG was recorded, and evoked brain reactions were analysed (0–700 ms from the clue). Differences between neutral and emotional pairs of conditions were determined (emotional modulation, EM). Study Results. Previous results for women with RD obtained in a larger sampling size and with a higher level of significance were confirmed. In healthy patients, EM was noted from 50 ms to 500 ms, whereas in patients with RD – from 130 ms to 700 ms for conditions where the clue was associated with neutral or ominous pictures of people. In clues with animals, EM was normally noted for components N170 and P200, while in patients with RD – for P200. Conclusion. Unconscious EM to socially important stimuli is preserved in RD, but it differs from the norm. Unconscious processing of emotional information associated with a biological threat causes lower component modulation. We observed a displacement of an “inert” EM towards posterior sections of the right hemisphere in women with RD. It can be assumed that such pattern demonstrates typical rigidity, an inclination to “stick” to unpleasant impressions; there are similar to pessimistic rumination. Keywords: emotional modulation, electroencephalogram, recurrent depression, visually evoked potentials.