Inflammation and treatment strategies for suicidal behavior

Suicide is a major global health problem. Growing evidence shows that immune dysregulation and inflammation contribute to suicidality. This review summarises inflammatory mechanisms associated with suicidal behaviour and evaluates emerging therapeutic strategies targeting these pathways.

A narrative literature review was conducted using a combination of keywords, including suicide, therapy, pharmacotherapy, and inflammation, with Boolean operators across PubMed and Google Scholar, emphasising risk factors and interventions aimed at reducing inflammatory activity and consequent suicidal behaviour.

Individuals with suicidal behaviour exhibit elevated pro-inflammatory cytokines (interleukin-6, interleukin-1β, tumour necrosis factor-α), C-reactive protein (CRP), and chemokines in blood, CSF, and brain tissue. These markers alter the hypothalamic-pituitary-adrenal (HPA) axis, monoamine systems, and glutamatergic signalling. Inflammatory activation of indoleamine 2,3-dioxygenase shifts tryptophan metabolism towards neurotoxic kynurenine metabolites, such as quinolinic acid, reducing serotonin and promoting NMDA-mediated excitotoxicity, potentially increasing impulsivity and acute suicidal ideation. Neuroinflammation also disrupts glutamate signalling through microglial/astrocytic dysfunction and altered Mammalian target of Rapamycin Complex 1 (mTORC1) pathways. Several immunomodulatory treatments - including lithium, ketamine/esketamine, cyclooxygenase-2 (COX-2) inhibitors, cytokine antagonists, and kynurenine-pathway modulators - show promise in reducing inflammation-linked to suicidal risk.

Precision-based approaches integrating inflammatory biomarkers, genetics, and clinical profiles may help identify individuals most likely to benefit from immunomodulatory therapies, supporting more personalised, biologically informed suicide-prevention strategies.