关键词: 血脑屏障, 口腔微生物, 紧密连接, 阿尔茨海默病

Abstract: Alzheimer's disease（AD）has become the fifth leading cause of death globally，yet the early modifiable risk factors for AD remain unclear. The blood-brain barrier（BBB）serves as the dynamic functional interface between the circulatory system and the central nervous system，and its completeness is critical in maintaining cerebral homeostasis and protecting the central nervous system. When the oral microbiota becomes imbalanced，pathogens and their virulence factors may traverse the circulatory system to reach the BBB because of the activated immune cells. They can compromise the barrier's protective function，invade the brain parenchyma，induce neuroinflammation，and trigger the critical ＂initiation-amplification＂ pathway central to AD pathogenesis. Therefore，elucidating the mechanisms by which oral microbial infections compromise the BBB and their role in AD holds significant importance for revealing the pathological mechanisms underlying neurodegenerative disorders. This article systematically reviews in vivo and in vitro evidence demonstrating how common oral microorganisms disrupt the BBB，drive neuroinflammation，and accelerate AD progression，aiming to provide a reference for exploring the association between the oral microbiome and neurodegenerative diseases.

Key words: blood-brain barrier, oral microorganisms, tight junctions, Alzheimer's disease