Serum Interleukin-6 Is a Predictive Biomarker for Ketamine’s Antidepressant Effect in Treatment-Resistant Patients With Major Depression

The N-methyl-D-aspartate receptor antagonist ketamine is the most attractive antidepressant therapy for treatment-resistant patients with major depressive disorder (MDD) and bipolar disorder ( 1 Aan Het Rot M. Zarate Jr, C.A. Charney D.S. Mathew S.J. Ketamine for depression: Where do we go from here?. Biol Psychiatry. 2012; 72: 537-547 Abstract Full Text Full Text PDF PubMed Scopus (291) Google Scholar , 2 Krystal J.H. Sanacora G. Duman R.S. Rapid-acting glutamatergic antidepressants: The path to ketamine and beyond. Biol Psychiatry. 2013; 73: 1133-1141 Abstract Full Text Full Text PDF PubMed Scopus (292) Google Scholar ). A single subanesthetic dose (.5 mg/kg) of ketamine produces a rapid antidepressant effect in two thirds of these patients, which can last for over a week ( 3 Zarate Jr, C.A. Brutsche N.E. Laje G. Luckenbaugh D.A. Venkata S.L.V. Ramamoorthy A. et al. Relationship of ketamine’s plasma metabolites with response, diagnosis, and side effects in major depression. Biol Psychiatry. 2012; 72: 331-338 Abstract Full Text Full Text PDF PubMed Scopus (198) Google Scholar , 4 Murrough J.W. Iosifescu D.V. Chang L.C. Al Jurdi R.K. Green C.E. Perez A.M. et al. Antidepressant efficacy of ketamine in treatment-resistant major depression: A two-site randomized controlled trial. Am J Psychiatry. 2013; 170: 1134-1142 Crossref PubMed Scopus (775) Google Scholar ). However, biomarkers able to differentiate between responding and nonresponding patients have yet to be identified ( 3 Zarate Jr, C.A. Brutsche N.E. Laje G. Luckenbaugh D.A. Venkata S.L.V. Ramamoorthy A. et al. Relationship of ketamine’s plasma metabolites with response, diagnosis, and side effects in major depression. Biol Psychiatry. 2012; 72: 331-338 Abstract Full Text Full Text PDF PubMed Scopus (198) Google Scholar , 5 Zarate Jr, C.A. Mathews D.C. Furey M.L. Human biomarkers of rapid antidepressant effects. Biol Psychiatry. 2013; 73: 1142-1155 Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar ).