Cytokines and their role in depression

PURPOSE. This study aims to review the cytokines that mediate the inflammatory process, the interleukins and the interferons, and the interaction of cytokines with serotonin as causative factors in the role of depression. CONCLUSIONS. Administration of proinflammatory cytokines to treat medical diseases induces depressive symptoms in humans. Patients diagnosed with depression tend to have high levels of cytokine activity and impaired immune response, as well as those patients suffering from inflammatory processes. Proinflammatory cytokines interfere with the body's feedback loop to reduce circulating corticosteroids during the stress response. PRACTICE IMPLICATIONS. Serotonin levels, integrally associated with depression, are lowered when levels of circulating cytokines are high when the precursor tryptophan is reduced.