Abstract

Background: Chronic cough is common and medical treatment can be ineffective. Mindfulness is a psychological intervention that aims to teach moment-to-moment non-judgemental awareness of thoughts, feelings and sensations.

Method: 30 healthy subjects and 30 chronic cough patients were studied in two sequential trials. For both studies, cough reflex sensitivity to citric acid (C5) was measured on two occasions with urge-to-cough rated following each inhalation; between challenges subjects were randomised to (i) no intervention (ii) mindfulness or (iii) no intervention but modified cough challenge (subjects suppress coughing). For the healthy volunteers, measures were one hour apart and mindfulness was practiced for 15 minutes. For the chronic cough patients measures were 1 week apart and mindfulness practiced daily for 30 minutes.

Results: In healthy volunteers, median change (IQR) in cough reflex sensitivity (logC5) for no intervention, mindfulness and suppression was +1.0(0.0 to +1.3), +2.0(+1.0 to +3.0) and +3.0(+2.8 to +3.0) doubling concentrations (dc) (p=0.003); significant reductions for both mindfulness (p=0.043) and suppression (p=0.002) over no intervention. In cough patients, median change (IQR) in logC5 for no intervention, mindfulness training and voluntary suppression was 0.0(-1.0 to +1.0), +1.0(-0.3 to +1.0) and +1.0(+1.0 to +2.0)dc, (p=0.046); significant reduction for suppression (p=0.02) but not mindfulness (p=0.35). Urge-to-cough did not change after mindfulness compared to control in either healthy (p=0.33) or chronic cough subjects (p=0.47).

Conclusion: Compared to control, mindfulness decreased cough reflex sensitivity in healthy volunteers, but did not alter cough threshold in chronic cough patients. Both groups were able to suppress cough responses to citric acid inhalation.