Protocol for a randomized comparison of integrated versus consecutive dual task practice in Parkinson's disease: the DUALITY trial

Abstract

Background: Multiple tasking is an integral part of daily mobility. Patients with Parkinson's disease have dual tasking difficulties due to their combined motor and cognitive deficits. Two contrasting physiotherapy interventions have been proposed to alleviate dual tasking difficulties: either to discourage simultaneous execution of dual tasks (consecutive training); or to practice their concurrent use (integrated training). It is currently unclear which of these training methods should be adopted to achieve safe and consolidated dual task performance in daily life. Therefore, the proposed randomized controlled trial will compare the effects of integrated versus consecutive training of dual tasking (tested by combining walking with cognitive exercises).

Methods and design: Hundred and twenty patients with Parkinson's disease will be recruited to participate in this multi-centered, single blind, randomized controlled trial. Patients in Hoehn & Yahr stage II-III, with or without freezing of gait, and who report dual task difficulties will be included. All patients will undergo a six-week control period without intervention after which they will be randomized to integrated or consecutive task practice. Training will consist of standardized walking and cognitive exercises delivered at home four times a week during six weeks. Treatment is guided by a physiotherapist twice a week and consists of two sessions of self-practice using an MP3 player. Blinded testers will assess patients before and after the control period, after the intervention period and after a 12-week follow-up period. The primary outcome measure is dual task gait velocity, i.e. walking combined with a novel untrained cognitive task to evaluate the consolidation of learning. Secondary outcomes include several single and dual task gait and cognitive measures, functional outcomes and a quality of life scale. Falling will be recorded as a possible adverse event using a weekly phone call for the entire study period.

Discussion: This randomized study will evaluate the effectiveness and safety of integrated versus consecutive task training in patients with Parkinson's disease. The study will also highlight whether dual task gait training leads to robust motor learning effects, and whether these can be retained and carried-over to untrained dual tasks and functional mobility.

Trial registration: Clinicaltrials.gov NCT01375413.

Figure 1

Design of the Duality study. PD: Parkinson’s disease. RUMC: Radboud University Nijmegen Medical Centre. KUL: Catholic University Leuven. DT: dual task. PT: physiotherapist.

Figure 2

Equipment used during training and testing. (a) MP3-player (DIFRNCE MP1850); (b) GaitRite Electronic Walkway System; (c) wireless headset system (Beyerdynamic; transmitter: t-bone DS16T and receiver: t-bone IEM100R); (d) large buttoned mobile phone (EmporiaTalkPremium).

Figure 3

Visual presentation of reaction and response times in Matlab R2011b. (a) Visual presentation of Backwards Digit Span task – green = stimulus that is heard by the patient, blue = answer of the patient; (b) Visual presentation of Stroop task. Since four stimuli per fragment are given, four reaction times per fragment can be calculated – green = stimulus that is heard by the patient, blue = answer of the patient.