Oral Infections and Cytokine Levels in Patients with Alzheimer's Disease and Mild Cognitive Impairment Compared with Controls

Background: Oral infections are prevalent in the adult population. Their impact includes the implication as a risk factor for Alzheimer's disease (AD), altering its progression. One of the potential mechanisms involves immune mediators such as circulating cytokines. Objective: The goal of the present study was to investigate the prevalence of oral infections and blood levels of IL-1 beta, TNF-alpha, and IL-6 in patients with AD, mild cognitive impairment (MCI), and controls. Methods: Sixty-five elderly were evaluated (25 AD, 19 MCI, and 21 controls) by the following methods: Mini Mental State Exam, Questionnaire of Functional Activities, periodontal and oral evaluation, and blood concentrations of IL-1 beta, TNF-alpha and IL-6. Results: Patients with AD had high serum IL-6 levels (p = 0.029), and patients with periodontitis had high serum TNF-alpha levels (p = 0.005). There was an association between IL-6 and TNF-alpha in patients with AD/MCI and periodontitis (p = 0.023). Conclusion: The increased levels of TNF-alpha and IL-6 in this study suggests their implication in the overlapping mechanisms between oral infections and AD. Longitudinal studies are necessary for further investigation.