Abstract
BACKGROUND: Swallowing function in individuals with Parkinson's disease (PD) can be negatively affected by dopaminergic medication with associated inhibition of brainstem reflexes. Three different "swallowing-safety" profiles of PD patients were previously observed, classified according to swallowing safety on and off levodopa. METHODS: Here, we investigated the effects of l-dopa on pulmonary function tests (PFTs) on 26 individuals with PD from the three different swallowing-safety profiles. PFTs results were compared to predicted values and direct comparisons between the groups with or without dysphagia were performed with nonparametric statistical tests (i.e., Kruskal-Wallis). RESULTS: A short (12-hour) withdrawal from l-dopa did not result in any significant changes in PFTs, and no differences on PFTs results were observed between the different dysphagic groups the on and off l-dopa state. No correlation was observed between the PFTs results with swallowing safety profiles of PD patients. CONCLUSIONS: Although deglutition seems to be at least partially affected by dopaminergic repletion, dopaminergic mechanisms do not seem to be responsible for PD patients' performance in PFTs.