A Literature Review: The Possible Role of Periodontal Diseases in Neurodegenerative Diseases

Abstract

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD) are characterized by neuronal death and subsequent degeneration in the central nervous system (CNS). The immune system and inflammatory processes are vital in the progression of these diseases. Growing evidence has linked various peripheral diseases, including cardiovascular disease, diabetes, and respiratory disorders, to the CNS through systemic inflammation. Inflammation in the oral cavity, particularly from periodontal diseases like gingivitis and periodontitis— which involve chronic inflammation of the gingiva, bone, and ligaments—also impacts the CNS. Inflammation in the oral cavity may reach the brain if associated cytokines, bacterial products, toxins, and bacteria spread to the CNS, which occurs via two main mechanisms: blood circulation and neural pathways. Neuroinflammation affects the initiation and progression of neurodegeneration and, therefore, neurodegenerative diseases. This paper presents the unified hypothesis that chronic periodontal inflammation can act as a systemic trigger, accelerating neurodegeneration across AD, PD, and HD through shared cytokine cascades. This review aims to expand upon AD - periodontal disease linkage, while also establishing a theoretical connection between PD, HD, and periodontal diseases, demonstrating the need for further research.