Measuring implicit sequence learning and dual task ability in mild to moderate Parkinson´s disease: A feasibility study.

Malin Freidle,Martin Lövdén,Hanna Johansson,Urban Ekman,Alexander V Lebedev,Erika Franzén,Imre Cikajlo

doi:10.1371/journal.pone.0251849

Abstract

We investigated the feasibility aspects of two choice reaction time tasks designed to assess implicit sequence learning and dual task ability in individuals with mild to moderate Parkinson's disease in comparison to healthy individuals. Twelve individuals with mild to moderate Parkinson's disease and 12 healthy individuals, all ≥ 60 years of age, were included. A serial reaction time task was used as a measure of implicit sequence learning and a similar task but with the addition of a simple counting task, was used as a measure of dual task ability. We have present thorough descriptive statistics of the data but we have refrained from any inferential statistics due to the small sample size. All participants understood the task instructions and the difficulty level of both tasks was deemed acceptable. There were indications of task fatigue that demand careful choices for how best to analyse the data from such tasks in future trials. Ceiling effects were present in several accuracy outcomes, but not in the reaction time outcomes. Overall, we found both tasks to be feasible to use in samples of individuals with mild to moderate Parkinson's disease and healthy older individuals.

Highlights

Parkinson’s disease (PD) is an age-related neurodegenerative disorder
We investigated the feasibility of two tasks designed to primarily assess implicit motor sequence learning and dual task ability in elderly individuals with mild to moderate PD and in elderly healthy individuals
The feasibility of the two tasks was supported but considerations in relation to task fatigue and ceiling effects for some accuracy outcomes are important for future use of the tasks

Summary

Introduction

Parkinson’s disease (PD) is an age-related neurodegenerative disorder. It is mainly characterized by progressive loss of dopamine cells in the substantia nigra and lowered levels of dopamine available for neurotransmission. The disease encompasses a wide range of motor and cognitive symptoms such as rigidity (muscle stiffness), bradykinesia (small, slow movements) and deficits in balance and gait, executive functions, and memory [1, 2]. Research indicates deficits in motor learning and dual-tasking i.e., the simultaneous performance of two tasks, in individuals with PD [3–5]. The deficits in motor learning that individuals with PD.

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