Cough, an important respiratory symptom, predominantly involves the brainstem, and the urge-to-cough is modulated by the cerebral cortex. Lewy body disease is associated with decreased cough reflex sensitivity and central respiratory chemosensitivity. Additionally, the insula, associated with the urge-to-cough, shows decreased activation and atrophy in dementia with Lewy bodies (DLB).
We investigated the relationships between cognition and cough reflex and the urge-to-cough and compared the differences in responses of patients with DLB and other dementia subtypes.
We conducted a cross-sectional study within a geriatric ward of a university hospital involving elderly patients diagnosed with Alzheimer’s disease (AD), DLB, or non-dementia (controls). The cough reflex sensitivities were estimated based on the lowest concentrations of inhaled citric acid that could induce ≥2 coughs (C2) or ≥5 coughs (C5). Subjects were asked to rate the urge-to-cough based on the threshold concentrations (Cu) using the modified Borg scale.
C2, C5, and Cu were negatively correlated with cognitive function in female participants but not in males (P<0.01). The cough reflex sensitivity expressed as C2 and C5 were significantly higher in the DLB group than in the AD and control groups (P<0.01 adjusted for gender). The urge-to-cough threshold expressed as Cu was also significantly higher, while the urge-to-cough log–log slope was less responsive with the increasing cough-evoking stimuli in the DLB group than that in the other groups.
The cough reflex sensitivity and perceived urge-to-cough deteriorated in the DLB group than in the other groups. This result might be valuable in treating patients with DLB.
All clinical and instrumental examinations were performed in a University Hospital setting as part of clinical care for patients with neurodegenerative disease. This study was conducted in accordance with the regulations of the Institutional Review Board and the Declaration of Helsinki. Written informed consent was obtained from all patients and their data were treated under the local privacy rules and regulations.
Japan Agency for Medical Research and Development, Award: JP17dk0110024
Japan Society for the Promotion of Science, Award: (C) KAKENHI (26460899)
Japan Society for the Promotion of Science, Award: Grant-in-Aid for Challenging-Exploratory-Research(15K12588)