Respiratory-Swallow Training and Variable Practice in Parkinson's Disease: A Clinical Trial Pilot Study

Dysphagia in people with Parkinson's disease (PwPD) is closely linked to impairments in respiratory-swallow coordination. Respiratory-swallow training (RST) is a promising, mechanism-based intervention for dysphagia, but, to date, only a single-subject study has examined RST in PwPD. As an early-stage next step in refining RST for PwPD, this clinical trial pilot study aimed to: (1) explore the preliminary associations between exhale-swallow-exhale (EX-EX) RST and swallowing safety, swallowing efficiency, and respiratory phase patterning; and (2) explore differences in practice structure (constant vs. variable practice) on RST-related motor learning outcomes.

PwPD completed pre-RST assessments, four once-weekly sessions of RST targeting only the EX-EX pattern, and post-RST assessments. Participants were randomized to constant practice or variable practice training conditions. Outcomes were measured using nasal airflow, respiratory inductive plethysmography, submental surface electromyography, and flexible endoscopic evaluation of swallowing. Multilevel statistical models were used to evaluate changes in EX-EX usage, pharyngeal residue, penetration, and aspiration.

Twelve PwPD completed all study phases, yielding an analysis of 1,565 swallows. In this pilot sample, EX-EX usage was higher post-RST compared to pre-RST (p < 0.05), with EX-EX usage observed to be higher at 1-month follow-up in the variable practice group compared to the constant practice group (p < 0.05). Additionally, pharyngeal residue, laryngeal vestibule residue, vocal fold residue, and Penetration-Aspiration Scale scores were lower post-RST compared to pre-RST (p < 0.05).

This clinical trial pilot study provides preliminary evidence that RST may be associated with increased EX-EX usage, swallowing safety, and swallowing efficiency in PwPD. Preliminary evidence also suggests that variable practice may enhance retention and generalization of EX-EX usage, warranting further evaluation. Findings from this study will be used to inform refinement of RST for PwPD and the design of future confirmatory randomized clinical trials.