Oral microbiota and central nervous system diseases: A review

Oral microbiota is the second largest microbial colony in the body and forms a complex ecological community that influences oral and brain health. Impaired homeostasis of the oral microbiota can lead to pathological changes, resulting in central nervous system (CNS) diseases. However, the mechanisms and clinical value of how the oral microbiome influences the brain remain unclear. This review summarizes recent clinical findings on the role of the oral microbiota in CNS diseases and proposes potential approaches to understand the way the oral microbiota and brain communicate. We propose three underlying patterns involving neuroinflammation, neuroendocrine regulation, and CNS signaling between oral microbiota and CNS diseases. We also summarize the clinical characteristics and potential utilization of the oral microbiota in ischemic stroke, Alzheimer's and Parkinson's disease, intracranial aneurysms, and mental disorders. Although the current findings are preliminary and clinical evidence is incomplete, oral microbiota is a potential biomarker for the clinical diagnosis and treatment of CNS diseases.