Exploring a Potential Blood Test to Diagnose Major Depressive Disorder

This proposed study will be an ancillary study to clinical trial NCT00555997 (www.clinicaltrials.gov) entitled: "A 12-Week, Randomized, Double-Blind, Placebo-Controlled, Parallel-Sequential Trial of Ziprasidone as Monotherapy for Major Depressive Disorder" (MDD)." Precision Human Biolaboratory ("PHB") is attempting to develop a proprietary blood test intended to potentially serve as a biological marker ("bio-marker") for MDD. Specifically, PHB's research team will employ a unique approach towards developing a diagnostic test for MDD: measures from multiple blood-based biological markers will be obtained from patients with MDD and then analyzed with the use of several interrelated algorithms in order to derive a single biological measure ("bio-marker") with a high predictive value for MDD. PHBs' test panel of blood-based biological markers will consist of a number of cytokines, stress related hormones, and binding proteins that have each been linked to MDD. This innovative test panel is expected to provide general practice physicians with a tool to more accurately identify and classify patients with MDD which, in turn, could potentially , allow for the more effective monitoring of pharmacotherapy (antidepressant drug therapy). Thus, the development of a highly reliable biomarker for MDD could improve the standard of care for depression. For this ancillary study, 120 antidepressant-free outpatients with MDD who have been deemed eligible to participate in trial NCT00555997 will be recruited from participating centers. Participating subjects will undergo a blood draw during the baseline visit for NCT00555997. Values obtained will be compared with those of "healthy controls" (defined as research subjects who have not met criteria for any lifetime Axis-I disorder (DSM-IV)) from an existing dataset at PHB.