The efficacy of imagery in the rehabilitation of people with Parkinson’s disease: protocol for a systematic review and meta-analysis

Background: Parkinson’s disease (PD) is a neurodegenerative disorder of the nervous system that affects movement. Individuals with PD commonly experience difficulty initiating movements, slowness of movements, decreased balance, and decreased standing ability. It has been shown that these motor symptoms adversely affect the independence of individuals with PD. Imagery is the cognitive process whereby a motor action is internally reproduced and repeated without overt physical movement. Recent studies support the use of imagery in improving rehabilitation outcomes in the PD population. However, these data have inconsistencies and have not yet been synthesised. The study will review the evidence on the use of imagery in individuals with PD and to determine its efficacy in improving rehabilitation outcomes. Methods: Randomised controlled clinical trials comparing the effects of imagery and control on activities, body structure and function, and participation outcomes for people with PD will be included. A detailed computer-aided search of the literature will be performed from inception to June 2021 in the following databases: MEDLINE, EMBASE, CINAHL, PsycINFO, Cochrane Library, Web of Science, and Scopus. Two independent reviewers will screen articles for relevance and methodological validity. The Physiotherapy Evidence Database (PEDro) scale will be utilised to evaluate the risk of bias of selected studies. Data from included studies will be extracted by two independent reviewers through a customised, pre-set data extraction sheet. Studies using imagery with comparable outcome measures will be pooled for meta-analysis using the random effect model with 95% CI. If individual studies are heterogeneous, a descriptive review will analyse variance in interventions and outcomes. A narrative data analysis will be considered where there is insufficient data to perform a meta-analysis. Discussion: Several studies investigating imagery in the PD population have drawn dissimilar conclusions regarding its effectiveness in rehabilitation outcomes and clinical applicability. Therefore, this systematic review will gather and critically appraise all relevant data, to generate a conclusion and recommendations to guide both clinical practice and future research on using imagery in the rehabilitation of people with PD. Funding: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Systematic review registration: PROSPERO registration number CRD42021230556.