Increased serum levels of sortilin-derived propeptide after electroconvulsive therapy in treatment-resistant depressed patients

PURPOSE: Sortilin-derived propeptide (PE) and its synthetic analog spadin show strong antidepressant activity in rodents and, therefore, could be used as a biomarker to evaluate the clinical efficacy of antidepressant treatments. The aim of this study was to determine whether electroconvulsive therapy (ECT) modulates serum PE concentration in patients with treatment-resistant depression (TRD). PATIENTS AND METHODS: Forty-five patients with major depressive disorder, who met the Diagnostic and Statistical Manual of Mental Disorders-IV criteria, were selected for this study. RESULTS: We did not observe any difference in the PE levels between TRD patients and controls (z=0.10, P=0.92), but we found a strong significant increase between the PE levels measured just before (T0) and about 1 month (T2) after ECT (z=−2.82, P=0.005). A significant difference between T0 and T2 was observed only in responders (z=−2.59, P=0.01), whereas no effect was found in nonresponders (z=−1.27, P=0.20). Interestingly, we found a significant correlation between the increase in PE levels and decrease in Montgomery -Åsberg Depression Rating Scale scores for the total patient sample (P=0.03). CONCLUSION: This study indicates for the first time that ECT affects serum PE concentration in responders and, therefore, could contribute to the evaluation of the therapy success.