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

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). Forty-five patients with major depressive disorder, who met the criteria, were selected for this study. We did not observe any difference in the PE levels between TRD patients and controls ( =0.10, =0.92), but we found a strong significant increase between the PE levels measured just before (T0) and about 1 month (T2) after ECT ( =-2.82, =0.005). A significant difference between T0 and T2 was observed only in responders ( =-2.59, =0.01), whereas no effect was found in nonresponders ( =-1.27, =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 ( =0.03). 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.