Changes in inflammatory markers following electroconvulsive therapy in severe psychiatric disorders: focus on monocyte-to-lymphocyte ratio and systemic inflammation response index.

Objective: This study aimed to evaluate changes in peripheral inflammatory markers before and after electroconvulsive therapy (ECT) in patients with schizophrenia (SCZ), bipolar disorder (manic and depressive episodes), and major depressive disorder, focusing on composite indices less frequently investigated in this context.

Methods: A retrospective analysis was conducted on 154 patients who received ECT. Inflammatory markers included neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and aggregate index of systemic inflammation (AISI). Pre- and post-ECT values were compared using Wilcoxon's signed-rank tests. Group differences were examined using Kruskal-Wallis and Mann-Whitney U-tests with Bonferroni's correction.

Results: Significant reductions were observed in MLR (median Δ = -0.04) and SIRI (median Δ = -1.01) after ECT (p = .001 and .031, respectively), both with medium effect sizes. NLR, PLR, SII, and AISI did not show significant changes. The magnitude of reduction in MLR and SIRI was greater in patients with bipolar mania and SCZ compared to those with depressive disorders, although these differences emerged primarily in between-group comparisons.

Conclusions: ECT appears to selectively reduce monocyte-related inflammatory markers (MLR, SIRI), with the most substantial decreases seen in bipolar mania and SCZ. These findings support a role for systemic inflammation in severe mood and SCZ-spectrum disorders and suggest that composite hematological indices may serve as useful biomarkers for tracking ECT's immunomodulatory effects.