Effect of experimental modulation of mood on exertional dyspnoea in chronic obstructive pulmonary disease

Abstract

Background and objective: Dyspnoea is a debilitating symptom in individuals with chronic obstructive pulmonary disease (COPD) and a range of other chronic cardiopulmonary diseases and is often associated with anxiety and depression. The present study examined the effect of visually-induced mood shifts on exertional dyspnoea in individuals with COPD.

Methods: Following familiarization, 20 participants with mild to severe COPD (age 57-79 years) attended three experimental sessions on separate days, performing two 5-min treadmill exercise tests separated by a 30-min interval on each day. During each exercise test, participants viewed either a positive, negative or neutral set of images sourced from the International Affective Picture System (IAPS) and rated dyspnoea or leg fatigue (0-10). Heart rate (HR) and peripheral oxygen saturation (SpO₂ ) were measured at 1-min intervals during each test. Mood valence ratings were obtained using Self-Assessment Manikin (SAM) scale (1-9).

Results: Mood valence ratings were significantly higher when viewing positive (end-exercise mean ± SEM = 7.6 ± 0.3) compared to negative IAPS images (2.4 ± 0.3, p < 0.001). Dyspnoea intensity (mean ± SEM = 5.8 ± 0.4) and dyspnoea unpleasantness (5.6 ± 0.3) when viewing negative images were significantly higher compared to positive images (4.2 ± 0.4, p = 0.004 and 3.4 ± 0.5, p = 0.003). Eighty-five percent of participants (n = 17) met the minimal clinically important difference (MCID) criteria for both dyspnoea intensity and unpleasantness. HR, SpO₂ and leg fatigue did not differ significantly between conditions.

Conclusion: These findings indicate that the negative affective state worsens dyspnoea in COPD, thereby suggesting strategies aimed at reducing the likelihood of negative mood or improving the mood may be effective in managing morbidity associated with dyspnoea in COPD.

Keywords: COPD; IAPS; chronic obstructive pulmonary disease; exertional dyspnoea; leg fatigue; mood modulation; treadmill exercise.