Altered concentrations of systemic inflammatory biomarkers after electroconvulsive therapy in schizophrenia and their relationship with treatment

Abstract

Background and hypothesis: Platelet count (PLT), neutrophils, lymphocytes, monocytes and three important ratios calculated from them: NLR, PLR and MLR are inexpensive and accessible biomarkers of systemic inflammation. Electroconvulsive therapy (ECT) is a rapid and effective physical therapy for schizophrenia, but the exploration of its therapeutic mechanisms is still in the early stages. Here we hypothesized the concentrations of systemic inflammatory biomarkers are higher in schizophrenia and decreased after electroconvulsive therapy. Elevated systemic inflammatory biomarkers were associated with less improvement in psychiatric symptoms and cognitive function after ECT. Study design: This study included 70 patients with schizophrenia (all patients have been treated with antipsychotic medication for a fortnight before ECT) as well as age- and sex-matched 70 healthy controls. We compared the differences of systemic inflammatory biomarkers between schizophrenia and healthy controls, and then determined the changes of systemic inflammatory biomarkers in schizophrenia before and after 6 times of electroconvulsive therapy. Positive and negative symptom scale (PANSS) were used to measure psychiatric symptom of patients with schizophrenia, and Mini-Mental State Examination (MMSE) were used to measure the cognitive function. Spearman correlation analysis was used to assess the relationship between systemic inflammatory biomarkers and clinical symptoms. Results: At baseline, peripheral blood PLT, neutrophils, monocytes and three important ratios: NLR, PLR and MLR were significantly higher in patients with schizophrenia than in healthy controls (all P<0.05), while lymphocytes did not differ between the two groups. After 6 ECT, neutrophils and NLR significantly decreased, and there was a downward trend in monocytes and MLR. Although PLR and lymphocytes were unchanged after ECT, lymphocytes were significantly higher in remitters than in the non-remitters, and PLR was significantly lower than in the non-remitters. Moreover, the higher the baseline NLR, PLR and MLR, the less improvement in positive symptoms after ECT; and the higher the baseline monocytes, the worse the cognitive function after ECT. Lymphocytes as a protective factor, although unchanged before and after ECT, were negatively associated with total PANSS score, positive symptom score and positively associated with reduction rate of PANSS after ECT. Conclusions: Our results further emphasize the presence of systemic inflammation in schizophrenia and that electroconvulsive therapy may exert a therapeutic effect in part by attenuating systemic inflammation in schizophrenia. Thus, further studies may lead to new treatment strategies for schizophrenia targeting immune system.