Mood Disorders related to Alterations in the Levels of Interleukin 6 in Critically Ill Patients

Interleukins (ILs) exert a pleiotropic action in various systems of the human body and a correlation between alterations in the levels of ILs and the mood of patients has been proposed. The purpose of this review is to present data on the interaction between IL-6 and the serotonin system, and to explore the role of IL-6 in depression and delirium in critically ill patients. According to the international literature, an increase in IL-6 levels may lead indirectly to reduced serotonin synthesis in the brain and consequently to the development of dysthymia or even depressive syndrome in patients with or without another concurrent disease. Levels of IL-6 are high in patients during delirium. The increase of IL-6 levels in critically ill patients may influence them emotionally and could be related to a propensity for the development of depression or delirium in this group. Comprehension by the nursing staff of the pathophysiological mechanisms of the development of mood disorders in critically ill patients could improve their provision of adequate, holistic and personalized care.