Inflammatory Biomarkers in Acute Suicidal Behaviors

TL;DR

This paper reviews how inflammatory biomarkers may help predict suicidal behaviors in people with depression, offering potential objective tools for risk assessment.

Contribution

The paper systematically summarizes inflammatory biomarkers as potential objective indicators for acute suicidal behaviors in major depressive disorder.

Findings

Elevated levels of CRP, IL-6, TNF-α, and IL-1β are associated with suicidal individuals.

Reduced levels of IL-4 and IL-10 suggest an imbalance between immune-inflammatory and regulatory systems.

Hematological ratios like NLR and PLR may serve as low-cost indicators for suicide risk.

Abstract

This review focuses on suicidal ideation and attempts in the context of major depressive disorder. Despite clinical advances, suicide risk assessment still relies mainly on subjective evaluation. Emerging evidence highlights immune-inflammatory dysregulation as a biological link between depression and suicidality. This review summarizes current findings on inflammatory biomarkers as potential predictors of suicidal behavior. The discussed markers include acute phase proteins (C-reactive protein, homocysteine), hematological indices from routine blood tests (NLR, PLR, MLR, SII, NAR), and cytokines (IL-6, TNF-α, IL-1β, IL-4, IL-10). Many studies report increased levels of CRP, IL-6, TNF-α, and IL-1β and decreased IL-4 and IL-10 in suicidal individuals, reflecting an imbalance between the immune-inflammatory response system (IRS) and the compensatory immune-regulatory reflex system (CIRS). Such dysregulation may promote neuroinflammation and neurotoxicity via the kynurenine pathway. Hematological ratios offer inexpensive, accessible indicators that could complement psychiatric evaluation. However, heterogeneity across studies, lack of standardized cut-off values, and the influence of confounders such as age, sex, and medication limit their clinical utility. Inflammatory biomarkers currently hold potential as objective adjuncts—but not substitutes—to clinical judgment in assessing suicide risk.

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