How do periodontal infections affect the onset and progression of Alzheimer's disease?

Chronic infection can cause slow progressive dementia, cortical atrophy and amyloid deposition in the atrophic form of general paresis. Due to the fact that specific bacterial ligands can increase the expression of proinflammatory molecules that can activate innate and adaptive immune systems, inflammation may play a significant role in the pathogenesis of Alzheimer's disease (AD). Furthermore, there is a significant association between AD and various types of spirochete. Periodontitis is a prevalent and persistent peripheral infection that is associated with gram-negative anaerobic bacteria and is capable of showing localized and systemic infections in the host. Periodontal disease related pathogens and their inflammatory products contribute to systemic inflammation and the pathogenesis of AD. In this minireview, we propose a hypothetical link between periodontitis, type 2 diabetes and AD. We also present the possible mechanistic links between periodontitis-related inflammation, type 2 diabetes and AD. Since this condition is treatable, periodontitis may be a readily-modifiable risk factor for AD.