The Brain-Tooth Axis as an Early Predictor of Alzheimer's Disease

Alzheimer's disease (AD) is typically diagnosed after irreversible neuronal loss. Recent evidence links oral health deterioration-especially tooth loss, periodontal disease, and reduced masticatory function-to accelerated cognitive decline and dementia risk. Aging also promotes structural and immunological changes in the oral cavity, accelerating periodontal breakdown, microbiome dysbiosis, and functional tooth loss. This emerging "brain-tooth axis" suggests bidirectional interactions between the oral cavity and central nervous system via inflammatory, microbial, and sensory pathways. Periodontal inflammation, oral microbiome dysbiosis, and loss of trigeminal sensory input may promote neuroinflammation, amyloid accumulation, and hippocampal dysfunction. Conversely, early neural degeneration can impair oral maintenance and chewing behavior. This perspective outlines mechanistic hypotheses, clinical implications, and a research roadmap for integrating oral health metrics into multimodal AD risk prediction. Validating this axis could establish oral assessments as accessible biomarkers for early disease detection and prevention strategies.