# Oral Health and Cognitive Decline: A Systematic Review of the Periodontitis-Alzheimer's Connection
## 3 Results
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Authors** & **Type of Study** & **Aim of Study** & **Matherials and Methods** & **Results** \\ \hline \multirow{9}{*}{[PERSON] et al. (2019) [228]} & \multirow{9}{*}{Retrospective cohort study} & Retrospective cohort study of & \begin{tabular}{c} CP patients showed 6\% \\ higher risk of overall \\ dementia \\ \end{tabular} \\  & & & \begin{tabular}{c} Korean National Health \\ Insurance Service. CP was \\ defined based on diagnosis \\ codes and treatment records. \\ Participants were followed \\ from 2005 to 2015 for \\ dementia outcomes. \\ Adjusted hazard ratios \\ (aHRs) were calculated. \\ \end{tabular} & \begin{tabular}{c} Dementia showed 6\% \\ higher risk of overall \\ dementia (aHRs = 1.06, 95\% \\ CI: 1.01–1.11) and similar \\ increase for AD (aHR = 1.05, 95\% CI: 1.00–1.11). Risk of \\ VD was higher but not \\ statistically significant. \\ Healthy lifestyle behaviors \\ appeared to amplify CP’s \\ association with dementia. \\ \end{tabular} \\ \hline \multirow{9}{*}{\begin{tabular}{c} [PERSON] et al. \\ (2023) [229] \\ \end{tabular} } & \multirow{9}{*}{Interventional cohort study} & Investigate the & Prospective cohort study & \begin{tabular}{c} Periodontitis was associated \\ with 101 participants \\ aged \(\geq\) 60 years with \\ operating decline, as \\ well as the latter’s \\ progression, focusing \\ on blood-based \\ Alzheimer’s \\ biomarkers like p-Tau \\ and A\(\beta\)1-40. \\ \end{tabular} & \begin{tabular}{c} Investigate the \\ with 101 participants \\ aged \(\geq\) 60 years with \\ hypertension. Cognitive \\ decline was assessed using \\ ACE and MMSE. Periodontal \\ health evaluated through \\ clinical parameters. Blood \\ samples analyzed for p-Tau, \\ A\(\beta\)1-40, and other \\ biomarkers. \\ \end{tabular} & \begin{tabular}{c} Prospective cohort study \\ with lower cognitive scores \\ (MMSE: \(\beta=-1.5\), \(p<0.05\)) \\ and progression of cognitive \\ decline (HR = 1.8, 95\% CI: 1.0–3.1). Participants with \\ periodontitis had higher \\ plasma p-Tau (\(p<0.001\)) and \\ \(\beta\)1-40 levels, with latter \\ increasing significantly over \\ 2 years. \\ \end{tabular} } \\ \hline \multirow{9}{*}{\begin{tabular}{c} [PERSON] et al. (2024) \\ profiling study \\ \end{tabular} } & \multirow{9}{*}{\begin{tabular}{c} Compare the \\ subginguival \\ microphone of patients \\ with periodontitis and \\ AD with that of \\ cognitively unimpaired \\ periodicontitis. \\ \end{tabular} } & \begin{tabular}{c} Cross-sectional analysis of \\ 29 participants (15 AD and \\ 14 cognitively unimpaired). \\ Samples were collected from \\ buccal, supraginguival, and \\ subginguival regions. \\ Next-generation sequencing \\ and network analysis were \\ used to characterize \\ microbiome. \\ \end{tabular} & \begin{tabular}{c} Subginguival microbiome in \\ AD patients displayed higher \\ diversity and distinct \\ microbial composition \\ compared to cognitively \\ unimpaired participants. \\ Specific \\ periodontidnogens (e.g., \\ _Prootella_ spp., _Saccharibacteria_, _Treponema_) \\ were more prevalent in AD. \\ Findings highlight need for \\ targeted periodontal care in \\ AD patients to mitigate \\ potential pathogen-induced \\ systemic effects. \\ \end{tabular} \\ \hline \multirow{9}{*}{\begin{tabular}{c} [PERSON] et al. \\ (2024) [231] \\ \end{tabular} } & \multirow{9}{*}{\begin{tabular}{c} Cross-sectional \\ neuroimaging \\ study \\ \end{tabular} } & \multirow{9}{*}{\
\begin{tabular}{c} Cross-sectional study of \\ 40 participants \\ (aged \(\geq\) 50 years). \\ Periodontidnosis and \\ metrics of brain \\ structure and function \\ in cognitively normal \\ middle-aged and \\ elderly adults. \\ \end{tabular} } &
\begin{tabular}{c} Severe periodontitis was \\ negatively correlated with \\ cortical volume, area, \\ thickness, and brain function \\ metrics (e.g., default-mode \\ network, limbic network). \\ Mild periodontitis showed \\ positive correlations in some \\ regions, potentially \\ indicating compensatory \\ mechanisms. Periodontitis \\ was linked to systemic \\ inflammatory pathways and \\ neurodegeneration, \\ emphasizing its role as \\ modifiable risk factor \\ for dementia. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}