Changes in cytokine plasma levels during interpersonal psychotherapy (IPT) in unmedicated individuals with major depression: Association with responder status and known confounders

Cytokines and their soluble receptors have been implicated in the pathophysiology of major depression, and experimentally have been proven to modulate depressive symptoms. Although sound findings are subtle it is likely that certain cytokines are altered during major depressive episodes, and successful therapy normalizes these alterations. If this is true for the disorder and its therapy per se and not a mere medication effect such effects are to be found with psychotherapy only, as well. Therefore, we investigated the plasma levels of TNF-alpha, sTNFR-p55, sTNFR-p75 and leptin in the beginning and at the end in 24 patients undergoing interpersonal psychotherapy (IPT). We found that therapy response by HAMD was significantly associated with the relative change over time compared to baseline in TNF-alpha and sTNFR-p55 levels. While in the responders TNF-alpha levels decreased sTNFR-p55 levels increased. Whereas smoking, age and first vs. recurrent depressive episode did not have any effect gender, weight, and prior antidepressant medication did. The original figures at baseline and in the end were not affected by the treatment response status but by the confounders. In conclusion, we found that the response status is associated with differential changes in the plasma levels of TNF-alpha and sTNFR-p55 supporting a hypothesis that certain cytokines and soluble receptors are involved in the pathophysiology of major depressive episodes.