Drooling in Parkinson's Disease: Evidence of a Role for Divided Attention

Drooling is a frequently reported symptom in Parkinson's Disease (PD) with significant psychosocial impact and negative health consequences including silent aspiration of saliva with the associated risk of respiratory infections. It is suggested that in PD drooling is associated with inefficient oropharyngeal swallowing which reduces the effective clearance of saliva rather than hyper-salivation. This is compounded by unintended mouth opening and flexed posture increasing anterior loss of saliva. It is reported to occur most frequently during cognitively distracting concurrent tasks suggesting an impact from divided attention in a dual-task situation. However, this supposition has not been systematically examined. This study assessed whether frequency of saliva swallows reduced, and drooling severity and frequency increased, when people with PD engaged in a cognitively distracting task. 18 patients with idiopathic PD reporting daytime drooling on the Unified Parkinson's Disease Rating Scale (UPDRS) were recruited. They completed the Radboud Oral Motor Inventory for PD saliva questionnaire and the Montreal Cognitive Assessment. UPDRS drooling score, disease stage, duration, gender, and age were recorded. Swallow frequency and drooling severity and frequency were measured at rest and during a distracting computer-based language task. There was no significant difference between drooling severity at rest and during distraction (Wilcoxon signed rank test z=-1.724, p=0.085). There was a significant difference between at rest and distraction conditions for both drooling frequency (Wilcoxon signed rank test z=-2.041, p=0.041) and swallow frequency (Wilcoxon signed rank test z=-3.054, p=0.002). Participants swallowed less frequently and drooled more often during the distraction task. The frequency of saliva swallows and drooling are affected by divided attention in a dual-task paradigm. Further studies are needed to explore the exact role of attention in saliva management and the clinical applications in assessment and treatment.