Attentional resource allocation and swallowing safety in Parkinson's disease: a dual task study.

BACKGROUND Aspiration pneumonia is a leading cause of death in persons with Parkinson's disease (PD). Despite this, the mechanisms underlying dysphagia in this population are unclear. To date, researchers have not investigated the effects of varying cognitive demand on objective measures of swallowing safety. This study assessed whether swallowing safety could be disrupted by increasing cognitive demands during the task of swallowing. METHODS Twenty participants with moderate PD and dysphagia were tested while completing a novel dual task experimental paradigm under videofluoroscopy. In the dual task condition, participants swallowed 10 cc of thin liquid barium while completing a digits forward task. RESULTS Four females and 16 males completed the study. Results revealed differential effects to swallowing safety based on baseline measures of cognitive flexibility and attention. Participants with mild impairment in cognitive flexibility and attention demonstrated cognitive-motor interference with worsening of both swallowing and cognitive performance. In contrast, participants who were most impaired in the domains of cognitive flexibility and attention improved swallowing safety in the dual task condition. Additionally, decreased swallow timing durations existed in the dual task condition compared to the single task condition. CONCLUSIONS The results of this study support the hypothesis that supramedullary drive can influence the swallowing plan. Additionally, this study highlights the need for cognitive taxing during swallowing evaluations.