On the Impact of Smoking on The Oral-brain Axis: The Microbiome-Metabolism-Brain Interactions

Abstract

Systemic interactions between distant organs, such as the oral-brain axis, remain largely unknown. This study aimed to shed light on a specific aspect of these oral-brain interactions, by focusing on the brain, in the form of psychological traits, the oral microbiome, and metabolism (BMM) with respect to the influence of smoking on the oral microbiota. We analyzed three datasets covering microbiome composition, psychological traits, and metabolic pathways in smokers and non-smokers. We used Canonical Correlation Analysis (CCA) to reduce the dimensionality of the three different datasets into scalar variables, and network analysis to identify the interactions between important features of the BMM system. Nonlinear regression revealed steady state interactions, showing tight correlations between metabolic pathways and microbiome composition. Smoking weakens the directed interaction between metabolism and psychological traits. Sensitivity analysis demonstrated the systems robustness to small perturbations, but large disruptions could destabilize it, potentially leading to oral pathologies or psychological conditions. These findings highlight smokings complex role in BMM interactions and its implications for managing psychological conditions in smokers.