Toward a Unified Neuroimmune Framework for Infection-Associated Psychiatric Disorders.

BACKGROUND/OBJECTIVES: Neuroinflammation is increasingly recognized as a key mechanism linking infectious diseases with psychiatric disorders through interactions between peripheral immune activation, metabolic pathways, and brain network alterations. This review aimed to synthesize current evidence on the neuroimmune mechanisms and biomarkers underlying infection-associated psychiatric disorders. METHODS: A narrative literature review structured according to the SANRA (Scale for the Assessment of Narrative Review Articles) criteria was conducted using the Web of Science Core Collection, PubMed/MEDLINE, Scopus and PsycINFO databases. Boolean search strategies identified studies investigating neuroinflammatory biomarkers, neuroimmune mechanisms, and psychiatric outcomes associated with infectious diseases. The search (January 2022-30 June 2026) included 76 studies in the final qualitative analyses. RESULTS: The reviewed evidence consistently identified inflammatory cytokines and chemokines, complement proteins, blood-brain barrier markers, glial activation biomarkers, neuroaxonal injury markers, kynurenine pathway metabolites, neurotrophic factors, and neuroimaging markers as complementary indicators of infection-induced neuroimmune dysfunction. Across diverse bacterial, viral, parasitic, and systemic infections, these mechanisms converged on peripheral immune activation, blood-brain barrier disruption, microglial activation, kynurenine pathway dysregulation, impaired neurotrophic signaling, synaptic dysfunction, and altered brain network connectivity, contributing to depression, anxiety, psychosis, cognitive impairment, and fatigue. Based on these findings, a unified neuroimmune model integrating peripheral and central mechanisms is proposed. CONCLUSIONS: Neuroinflammation emerges as a shared biological pathway linking infections with transdiagnostic psychiatric phenotypes. Although no single biomarker currently demonstrates sufficient diagnostic specificity, integrated multimodal biomarker panels may improve biological stratification, facilitate earlier identification of high-risk patients, and support the development of mechanism-based precision approaches-including candidate anti-inflammatory pharmacological strategies currently under clinical investigation-for infection-associated psychiatric disorders.