Published online Nov 19, 2026. doi: 10.5498/wjp.123050
Revised: July 10, 2026
Accepted: July 30, 2026
Published online: November 19, 2026
Processing time: 140 Days and 22.5 Hours
The oral microbiome, as the largest and most diverse microbial community in the human body, has emerged as a potential contributor to brain health. However, the mechanistic pathways by which oral dysbiosis influences the pathogenesis of psychiatric disorders remain incompletely integrated, and its translational implications for clinical practice have yet to be fully elucidated. This minireview aims to systematically synthesize current evidence on the role of oral microbiome dysbiosis in psychiatric disorders, with a particular focus on neuroinflammation as the key mediating mechanism, and to discuss the clinical and translational implications of these findings. In contrast to prior reviews that have largely centered on the gut-brain axis or individual diagnostic categories, the current minireview synthesizes evidence on three neuroinflammatory pathways: Hematogenous, retrograde neural, and the oral-gut-brain axis by which oral dysbiosis may contribute to psychiatric outcomes. By consolidating findings across major psychiatric disorders and emphasizing neuroinflammation as a core mediating process, we propose an integrative framework that unites oral microbiology with psychiatric pathophysiology.
Core Tip: Oral microbiome dysbiosis can drive neuroinflammation and contribute to psychiatric disorders via three key pathways: Direct bloodstream invasion, neural retrograde transport along trigeminal and olfactory nerves, and disruption of the oral-gut-brain axis. Recent animal evidence showing that Lactobacillus supplementation alleviates anxiety- and depression-like behaviors reinforces the translational potential of targeting the oral microbiota. This minireview integrates these mechanisms and highlights the oral cavity as an accessible, modifiable target for novel diagnostic and adjunctive therapeutic strategies in psychiatry.