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

This systematic review evaluated the efficacy of therapeutic interventions on improving swallow, respiratory, and cough functions in Parkinson's disease (PD).

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.

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.

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.