Association between peripheral biomarkers and clinical response to IV ketamine for unipolar treatment-resistant depression: An open label study

•Major Depressive Disorder is the leading cause of disability worldwide.•A cohort of patients do not respond to currently available antidepressants.•Subanesthetic intravenous ketamine significantly decreases depressive (MADRS) scores.•BDNF throughout treatment inversely correlated to decreases in MADRS scores.•Higher baseline BDNF predicted mood responses at one- and four-weeks.