Periodontitis and systemic markers of neurodegeneration: A case-control study

Aim: To investigate whether periodontitis is associated with amyloid beta (Aβ) peptides and whether systemic inflammation could act as a potential mediator of this link.

Materials and methods: A case-control study was designed including 75 patients with periodontitis (cases) and 75 age-balanced and gender-matched participants without periodontitis (controls). Full-mouth periodontal evaluation was performed in all participants. Demographic, clinical and behaviour data were 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: Cases 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) when compared to controls (all p < .001). Diagnosis of periodontitis was statistically significantly associated with circulating Aβ_1-40 ( $\beta {\text{coefficient}}_{\text{adjusted}}$ = 6.9, 95% CI: 5.4-8.3; p < .001) and Aβ_1-42 ( $\beta {\text{coefficient}}_{\text{adjusted}}$ = 17.8, 95% CI: 14.4-21.3; p < .001). Mediation analysis confirmed hs-CRP and IL-6 as mediators of this association.

Conclusions: Periodontitis is associated with increased peripheral levels of Aβ. This finding could be explained by enhanced systemic inflammation that can be seen in patients with periodontitis.