Neuromuscular assessment of force development, postural, and gait performance under cognitive-motor dual-tasking in healthy older adults and people with early Parkinson's disease: Study protocol for a cross-sectional Mobile Brain/Body Imaging (MoBI) study

Abstract

Background: Neuromuscular dysfunction is common in older adults and more pronounced in neurodegenerative diseases. In Parkinson's disease (PD), a complex set of factors often prevents the effective performance of activities of daily living that require intact and simultaneous performance of the motor and cognitive tasks.

Methods: The cross-sectional study includes a multifactorial mixed-measure design. Between-subject factor grouping the sample will be Parkinson's Disease (early PD vs. healthy). The within-subject factors will be the task complexity (single- vs. dual-task) in each motor activity, i.e., overground walking, semi-tandem stance, and isometric knee extension, and a walking condition (wide vs. narrow lane) will be implemented for the overground walking activity only. To study dual-task (DT) effects, in each motor activity participants will be given a secondary cognitive task, i.e., a visual discrimination task for the overground walking, an attention task for the semi-tandem, and mental arithmetic for the isometric extension. Analyses of DT effects and underlying neuronal correlates will focus on both gait and cognitive performance where applicable. Based on an a priori sample size calculation, a total N = 42 older adults (55-75 years) will be recruited. Disease-specific changes such as laterality in motor unit behavior and cortical control of movement will be studied with high-density surface electromyography and electroencephalography during static and dynamic motor activities, together with whole-body kinematics.

Discussion: This study will be one of the first to holistically address early PD neurophysiological and neuromuscular patterns in an ecologically valid environment under cognitive-motor DT conditions of different complexities. The outcomes of the study aim to identify the biomarker for early PD either at the electrophysiological, muscular or kinematic level or in the communication between these systems.

Clinical trial registration: ClinicalTrials.Gov, NCT05477654. This study was approved by the Medical Ethical Committee (106/2021).

Keywords: Mobile Brain/Body Imaging (MoBI); Parkinson’s disease (PD); dual-tasking; neuromuscular function; older adults.

Figure 1.. Graphic depiction of each motor activity, timeline of the procedure, and randomization order.

( A) Overground walking will start with a resting-state EEG recording with both eyes closed and opened, followed by a baseline walk, and finally randomized order of ST and DT conditions during overground walking on either wide or narrow lanes with/or visual discrimination task (blue and purple light). ( B) Next, the semi-tandem stance will be performed, again using randomization of the ST and DT conditions across participants, while the 30-second segments within each condition will be kept at fixed order. ( C) Lastly, during the isometric knee contraction the order of the leg blocks and ST-sub will be randomized, while during each leg block, the ST will always be performed before the DT. Duration of each recording is denoted below the time axis. For a detailed explanation refer to the main text. Abbreviations: ST – single task, DT – dual task, sts – Semi-tandem stance, sub – subtraction or mental arithmetic task.