A systematic review of behavioural therapies for improving swallow and cough function in Parkinson’s disease

Abstract

Purpose: This systematic review evaluated the efficacy of therapeutic interventions on improving swallow, respiratory, and cough functions in Parkinson's disease (PD). Method: A PRISMA systematic search was implemented across six databases. We selected studies reporting pre- and post-assessment data on the efficacy of behavioural therapies with a swallow or respiratory/cough outcome, and excluded studies on medical/surgical treatments or single-session design. Cross-system outcomes across swallow, respiratory, and cough functions were explored. Cochrane’s risk of bias tools were utilised to evaluate study quality. Result: Thirty-six articles were identified and further clustered into four treatment types: swallow related (n = 5), electromagnetic stimulation (n = 4), respiratory loading (n = 20), and voice loading (n = 7) therapies. The effects of some behavioural therapies were supported with high-quality evidence in improving specific swallow efficiency, respiratory pressure/volume, and cough measures. Only eleven studies were rated with a low risk of bias and the remaining studies failed to adequately describe blinding of assessors, missing data, treatment adherence, and imbalance assignment to groups. Conclusion: Behavioural therapies were diverse in nature and many treatments demonstrated broad cross-system outcome benefits across swallow, respiratory, and cough functions. Given the progressive nature of the condition, the focus of future trials should be evaluating follow-up therapy effects and larger patient populations, including those with more severe disease.