Oral Environment and Aspiration Pneumonia Risk in Parkinson's Disease: A Narrative Review and Conceptual Framework

BACKGROUND: Aspiration pneumonia is a major clinical concern in Parkinson's disease (PD) and is associated with poor prognosis. Dysphagia is a well-recognized risk factor for aspiration pneumonia, but the oral environment may also contribute to this risk. OBJECTIVE: This narrative review aims to synthesize knowledge on the relationship between the oral environment and dysphagia in PD and to propose a conceptual framework that incorporates oral environment management into dysphagia management. METHODS: We searched PubMed, Scopus and Google Scholar for publications from January 2000 to December 2025. We synthesized findings on the oral environment in PD across three domains (clinical oral findings, saliva-related symptoms and the oral microbiome), with attention to disease stage where reported and examined their relationships with dysphagia. RESULTS: The oral environment in PD was reported to be associated with disease-related motor and non-motor features and was reported to worsen with disease progression. Deterioration of the oral environment was also associated with dysphagia. Based on these findings, we proposed a stage-based conceptual framework for assessment and management of both the oral environment and swallowing function. CONCLUSION: Assessment of both the oral environment and swallowing function across all disease stages should be considered as part of aspiration pneumonia risk management in PD. The oral environment remains a modifiable factor even in advanced stages of PD.