[Clinical-neurophysiological aspects of suicidal behavior]

Abstract

Eighty-two patients with depression with suicidal tendencies, 82 patients without these tendencies and 150 healthy people have been studied. An attempt has been made to reveal a correlation of results obtained in calculating the entropy and information saturation of EEG with signs of dysontogenesis in patients with depression with- or without suicidal signs. In patients with depressive symptoms and feelings of despair, the ability to process information in the prefrontal cortex went down; at the same time, a portion of information saturation of occipital regions significantly increased. In depressive patients with suicidal ideation, there was a statistically significant <<flooding>> of the brain with excessive amount of information. A total elevation of information processing activity in all cortical areas, especially in frontal and medial temporal areas and right occipital regions as well, to emotionally neutral stimulus was noticed in patients without suicidal signs. An increase of information saturation in frontal and medial temporal cortex areas, especially in the left side, to emotionally positive stimulation was shown. The similar but less marked changes were found for negative stimulus. The decrease of prefrontal cortical activity observed in this group did not reach the level of significance and was noticed, in contrast to healthy people, for both positive and negative (more significantly) stimulation. The study of suicide attempters revealed the same results, with more significant decreasing of information saturation to emotionally neutral stimulus in frontal cortical areas as compared to the positive and negative stimulation. The significant difference was found for the right frontal temporal cortical area. An analysis of EEG changes in view of dysontogenetic factors suggests that these factors lead to the dysfunction of mesodiencephal structures due to mechanisms of plasticity. The irritation of these structures lead to disturbances in information processing that might cause clinical and psychological changes resulted in the suicide.