[Causal impact of chronic periodontitis on brain corticospinal tract microstructures].

PURPOSE: To investigate whether periodontitis (PD) induces microstructural alterations in specific WM tracts, particularly the corticospinal tract (CST), which is associated with motor function.

METHODS

Based on genome wide association study (GWAS) summary statistics from PD (45 563 samples) and CST imaging-derived phenotypes (IDPs) (31 356 samples), two-sample Mendelian randomization (MR) analysis was performed. The primary analysis was conducted using inverse variance weighted (IVW) method, supplemented by weighted median (WM), MR-Egger regression, robust adjusted profile score (MR-RAPS), and constrained maximum likelihood and model averaging bayesian information criterion (cML). Sensitivity analysis was performed using Cochran Q test, Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO), and leave-one-out (LOO) analysis.

RESULTS

MR analysis revealed positive associations between PD and CST fractional anisotropy (FA)(β=0.07, P=6.11×10-3) and negative associations with mean diffusivity (MD)(β=-0.06, P=3.90×10-2). These findings remained consistent across sensitivity analysis. PD led to an increase in FA values and a decrease in MD within the CST, indicating that the integrity of the CST was compromised.

CONCLUSIONS

PD has a detrimental causal impact on the integrity of CST microstructures, potentially increasing the risk of CST lesions. Therefore, this study suggests that effective clinical prevention and treatment of PD are necessary.