Causal Association between Periodontitis and Parkinson's Disease: A Bidirectional Mendelian Randomization Study

Area of Science:

• Genetics
• Epidemiology
• Neurology

Background:

• Emerging evidence suggests a potential link between periodontitis and Parkinson's disease (PD).
• Understanding a potential causal relationship is crucial for public health and disease prevention strategies.
• Mendelian randomization (MR) offers a robust method to explore bidirectional causality using genetic variants.

Purpose of the Study:

• To investigate the potential bidirectional causal relationship between periodontitis and Parkinson's disease (PD).
• To utilize two-sample Mendelian randomization (MR) analysis to assess genetic liability for periodontitis influencing PD risk.
• To examine the reverse causation: whether genetic predisposition to PD affects the risk of periodontitis.

Main Methods:

• Employed two-sample Mendelian randomization (MR) analysis in European ancestry populations.
• Utilized genome-wide association study (GWAS) data for periodontitis and Parkinson's disease.
• Selected single-nucleotide polymorphisms (SNPs) as instrumental variables for both conditions, including validation sets.

Main Results:

• No significant evidence was found for periodontitis increasing the risk of Parkinson's disease (p=0.26).
• Validation analysis using independent SNPs confirmed no association between periodontitis genetic liability and PD risk (p=0.99).
• No association was detected for genetically predicted Parkinson's disease influencing periodontitis risk (p=0.19).

Conclusions:

• The findings do not support a bidirectional causal genetic link between periodontitis and Parkinson's disease.
• Current genetic evidence does not establish periodontitis as a causal factor for PD, nor PD as a cause for periodontitis.
• Further large-scale genome-wide association studies are recommended to confirm these results and explore potential confounding factors.