Circadian rhythms and influencing factors of xerostomia among Parkinson's disease patients

Objectives Parkinson's disease (PD) patients suffer from xerostomia, but limited information exists regarding associations with dysphagia, drooling, daily habits, PD characteristics, or possible circadian rhythms. Subjects and methods A questionnaire was administered, including (a) clinical characteristics (comorbidities, prescribed medications, levodopa equivalent daily dose [LEDD], disease duration); (b) self-assessment of dysphagia, xerostomia, drooling (10-cm visual analogue scale [VAS]); (c) 24-hr diary of motor impairment, dyskinesia, xerostomia, dysphagia, drooling, daily habits. Results Of 75 PD patients who completed the study, 67% reported dysphagia (mean +/- standard deviation VAS 4 +/- 2), 76% drooling (5 +/- 2), 77% xerostomia (5 +/- 2). Xerostomia was associated with comorbidities (p = 0.021) and smoking (p = 0.010) and affected by tremor (p = 0.003), dyskinesia (p = 0.010), dysphagia (p < 0.001), food intake (p = 0.005), sleep (p = 0.011), age (p = 0.018), medication intake (p = 0.063), LEDD (p = 0.052), daytime (p = 0.075), disease duration (p = 0.004). Xerostomia peaked at 9 a.m. and 9 p.m. Conclusions PD patients suffer from xerostomia, dysphagia, and drooling. Subjective dysphagia is associated with drooling and xerostomia, but drooling prevalence or intensity does not influence xerostomia symptoms. Tremor, dyskinesia, and disease duration, which characterise PD, affect xerostomia. Additionally, food intake, sleep, age, LEDD, and daytime (peaks at 9 a.m. and 9 p.m.) increase xerostomia occurrence. This knowledge may improve dentists' advice to patients and aid development of patient-centred, symptom-relieving products.