Variability of Voluntary Cough Airflow in Healthy Adults and Parkinson's Disease.

Cough is an important airway protective behavior responsible for ejecting material from the airway to prevent pneumonia, a leading cause of death in older adults and individuals with Parkinson's disease (PD). Variability of motor performance for both spinal and bulbar functions has been documented; however, there are no studies examining variability of cough motor control in PD and healthy controls. The present study examined the effects of age and PD on variability of voluntary cough performance. Twenty-five healthy younger adults (HYA), 26 healthy older adults (HOA), and 16 participants with PD completed three trials of sequential voluntary cough with spirometry. Coefficients of variation were used to examine variability between groups. Increased variability of cough expired volume (p = 0.012) and inspiratory volume (p = 0.006) was appreciated in HOAs compared to HYAs. Participants with PD demonstrated increased variability of cough expired volume (p = 0.029), peak expiratory flow rise time (p = 0.016), and cough volume acceleration (p = 0.034) compared to HOAs. Though participants with PD descriptively demonstrated increased peak expiratory flow rate compared to HOAs, this finding was statistically nonsignificant after adjusting for multiple comparisons (p = 0.072). This study identified that variability in cough airflow increases in healthy aging and Parkinson's disease. These motor control impairments may be attributed to age and disease-related sensorimotor changes in the peripheral and central nervous system. Future research will be necessary to examine the relationship between inconsistent cough motor output, airway invasion, and aspiration pneumonia in PD.