ASSOCIATION OF SERUM NARDILYSIN VARIABILITY WITH TREATMENT RESPONSE IN DEPRESSED PATIENTS

Abstract Background The cause of depression is still unknown, and no biological markers for pathophysiology or therapeutic response have been found. Nardilysin(NRDC) is a type of metalloendopeptidase that is associated with neurodevelopment, and comprehensive analysis of plasma proteins suggests that it may be a potential biological marker for depression. In the present study, we investigated the variation of NRDC in depressed patients treated with antidepressants and electroconvulsive therapy (ECT). The study was approved by the Ethics Committee of Shiga University of Medical Science. Aims & Objectives To search for biological markers of depression. Methods 15 depressed patients (11 females, mean age 63.2±15.5 years) admitted to the Department of Psychiatry, Shiga University of Medical Science were included in the study. All patients were treated with antidepressants, and 8 of them (6 females, mean age 60.5±17.2 years) were treated with ECT. Serum NRDC, depressive symptoms (assessed by MADRS), and antidepressant dose (imipramine-equivalent dose (IED, mg/day)) at admission and 6 weeks after admission and at discharge were investigated. The correlation between serum NRDC changes at admission and at 6 weeks (ratio of serum NRDC values at 6 weeks and at admission), treatment response (difference in MADRS scores at 6 weeks and at admission), and IEDs at admission and at discharge were analyzed. Results MADRS at admission and 6 weeks in 15 patients were 27.7±6.6 and 15.2±6.2, respectively; serum NRDC levels were 1224±746 and 901±279 pg/mL, respectively; and IED at admission and discharge were 123±143 and 142±116 mg/day. MADRS at 6 weeks was significantly lower than admission significantly decreased compared to MADRS (t=4.64, p<0.001). A positive correlation (Spearman's ρ=0.54, p=0.038) was found between changes in serum NRDC levels at admission and at 6 weeks and treatment response. On the other hand, there was no significant correlation between IEDs at admission and discharge, serum NRDC and its fluctuation at admission and 6 weeks, and treatment response. Discussion In the treatment of depression, the greater the percentage decrease in serum NRDC from admission to 6 weeks, the greater the decrease in MADRS. Although the number of cases was small, the results suggest that serum NRDC levels may be a potential biological marker for depression treatment.