Periodontitis and Systemic Markers of Neurodegeneration. A case-control study.

Objectives: To compare levels of amyloid beta (Aβ) peptides and systemic inflammation markers in otherwise healthy periodontal patients and controls. Also to investigate whether Aβ peptides are associated with periodontitis and if systemic inflammation could be the mediator of this association.
Methods: A case-control study was designed including 75 patients with periodontitis and 75 age- and sex-matched subjects without periodontitis. Full-mouth periodontal evaluation was done in all participants. Demographic, clinical and behaviour information was also recorded. Fasting blood samples were collected and serum levels of interleukin 6 (IL-6), high sensitivity C-reactive protein (hs-CRP), Aβ_1-40 and Aβ_1-42 were determined.
Results: Periodontal patients showed higher levels of IL-6 (8.7±3.2 vs. 4.8±0.5 pg/mL), hs-CRP (3.3±1.2 vs. 0.9±0.7 mg/L), Aβ_1-40 (37.3±6.0 vs. 30.3±1.8 pg/mL) and Aβ_1-42 (54.5±10.6 vs. 36.5±10.0 pg/mL) compared to controls (all p<0.001). Clinical periodontal parameters correlated positively to Aβ peptides and inflammation (all p<0.001). Circulating Aβ₁₄₀(OR_adjusted=1.764, 95%CI: 1.410-2.208; p<0.001) and Aβ₁₄₂ (OR_adjusted=1.191, 95%CI: 1.124-1.262; p<0.001) were associated with the presence of periodontitis. Mediation analysis showed that hs-CRP and IL-6 are significant mediators of this relationship accounting for half of the indirect effect (percentage mediated ranged from 49% to 63%).
Conclusions: Increased peripheral levels of Aβ are associated with periodontitis. These findings could be explained by enhanced systemic inflammation that can be seen in periodontal patients.