A pilot study of respiration and swallowing integration in Parkinson's disease: "on" and "off" levodopa

Parkinson's disease is associated with both swallowing and respiratory dysfunction, increasing the risk of aspiration and pneumonia. Previous studies have shown improvements in measurements of swallowing and respiration with levodopa; however, the studies are small and some studies show conflicting reports. The aim of this study was to further investigate the effect of levodopa on respiration. Ten patients with Parkinson's disease were tested "On" and "Off" levodopa. Assessments included Unified Parkinson's Disease Rating Scale (UPDRS), coordination of swallowing and respiration, timed-test of swallowing, lung function testing, and, qualitative assessment of swallowing. There was a nonsignificant trend to lower volume per swallow when "On" levodopa, significant reduction in lung function when "On" levodopa, but no difference in coordination of swallowing and respiration or qualitative assessment of swallowing. There was a significant increase in motor examination score of the UPDRS when "Off" levodopa compared to "On." There may be a reduction in efficiency of swallowing with levodopa medication without any apparent increase in risk of aspiration. These pilot data suggest that further evaluation with larger numbers of participants is justified.