Differences in Modulation of Brain Responses to Emotional Stimuli in Men and Women with Bipolar Depression

Abstract

Study Objective: To investigate the prognostic and therapeutically significant characteristics in neurophysiological reactivity of male and female patients with bipolar depression. Study Design: comparative controlled non-randomized clinical experimental study. Materials and Methods. 53 patients (26 men and 27 women) with bipolar depression were examined before the start of their psychopharmacotherapy. They were aged from 21 to 59 years. There were no significant differences between men and women on the Hamilton Depression and Anxiety Scale. The groups of healthy volunteers included 23 men and 29 women of the corresponding age. The participants sorted the photos, 80 of which were images of angry/aggressive people or animals, and 80 had neutral expressions. Simple figures (keys) were displayed 2 seconds before the pictures, their connection with the photographs was not explained. A 128-channel electroencephalogram was recorded and the brain responses elicited by the keys were analyzed. Differences (p < 0.05) between neutral and emotional conditions were defined as emotional modulation (EM). Study Results. EM differences in male and female patients were more pronounced than in the control groups. In women with bipolar depression, EM was consistently located in the posterior areas of the cortex from 100 ms to the end of the analysis period. The EM for the P100 component was missing, and the EM topography for P200 was closer to normal than in men. The EM of components N170 and P380 in patients differed depending on their sex and differed from EM of healthy controls of the same sex. Conclusions. The EM of the brain activity in patients with bipolar depression differs from the EM of healthy people. The differences depend on the gender of the patient and affect several components of the evoked brain activity. This suggests that it is important to take into account the gender of the subjects when studying affective disorders in patients. Keywords: emotional modulation, high-density EEG, bipolar depression, implicit learning, facial expression, anger.