Oral Dysbiosis and Neuroinflammation: Implications for Alzheimer's, Parkinson's and Mood Disorders.

backgroundGrowing evidence indicates that oral microbiome dysbiosis contributes to systemic inflammation, immune activation, and neural dysfunction. These processes may influence the onset and progression of major neuropsychiatric and neurodegenerative disorders. This review integrates clinical, epidemiological, and mechanistic findings linking periodontal pathogens and oral microbial imbalance to Alzheimer's disease (AD), Parkinson's disease (PD), depression, and anxiety.

methodsA narrative review was conducted using PubMed/MEDLINE, Scopus, Web of Science, and Google Scholar to identify recent studies examining alterations in the oral microbiota, microbial translocation, systemic inflammatory responses, blood-brain barrier disruption, cytokine signaling, and neural pathways implicated in brain disorders.

resultsEvidence from human and experimental models demonstrates that oral pathogens, particularly

conclusionsOral dysbiosis emerges as a modifiable contributor to neuroinflammation and brain health. Periodontal therapy, probiotics, prebiotics, synbiotics, and targeted inhibitors of bacterial virulence factors represent promising strategies to reduce systemic and neural inflammation. Longitudinal human studies and standardized microbiome methodologies are still needed to clarify causality and evaluate whether restoring oral microbial balance can modify the course of neuropsychiatric and neurodegenerative disorders.