The aim of this study is to evaluate gait in individuals diagnosed with PD under tasks involving different cognitive domains, to compare the results with those of age and sex-matched healthy individuals, and to determine which cognitive function has the greatest impact on gait in PD.
Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the coexistence of motor and non-motor symptoms, which negatively affect individuals' activities of daily living and quality of life. Although motor symptoms are predominant in PD, impairments in cognitive functions are known to be present from the early stages of the disease and contribute to the clinical picture, thereby limiting functional abilities such as gait. Cognitive functions play a critical role in the planning, initiation, and maintenance of gait. As one of the key determinants of independence, walking is often performed under cognitive load in daily life. The ability to perform motor and cognitive dual tasks simultaneously during walking requires effective attentional allocation and increased information processing speed, and the central nervous system is capable of adapting to these demands. However, in neurodegenerative diseases such as PD, the simultaneous execution of cognitive and motor tasks becomes more challenging, leading to difficulties in maintaining balance during gait and an increased risk of falls. Cognition encompasses multiple domains, including memory, attention, executive functions, language, and visuospatial abilities. Although it is known that cognition affects gait performance in PD, the specific contributions of each cognitive domain to gait are not yet fully understood. Therefore, investigating the effects of cognitive tasks on gait performance in PD represents an important area of research. It is anticipated that the findings of this study will contribute to the development of structured gait training programs aimed at improving functional independence in gait-related activities of daily living in individuals with PD. Furthermore, these findings are expected to support the development of effective and individualized strategies for fall prevention, which remains one of the major challenges in physiotherapy management of PD.
Study Type
OBSERVATIONAL
Enrollment
30
Gazi University, Faculty of Health Sciences, Department of Physiotherapy and Rehabilitation.
Ankara, Turkey (Türkiye)
Global Cognition Assessed by the Montreal Cognitive Assessment
The assessment of cognitive functions will begin with the evaluation of global cognition. Global cognition will be evaluated using the Montreal Cognitive Assessment (MoCA). The Montreal Cognitive Assessment is a validated scale designed to assess multiple cognitive functions, including attention, concentration, executive functions, memory, language, visuospatial skills, abstract reasoning, calculation, and orientation. The instrument has a maximum total score of 30 points. According to the original validation study, scores of 26 and above are generally considered to represent normal cognitive function, whereas scores below 26 are reported to indicate potential cognitive impairment. For the purpose of this study, an inclusion criterion of a MoCA score ≥ 21 has been established.
Time frame: Day 1
Language Function Assessed by the Boston Naming Test
The short form of the Boston Naming Test (BNT), consisting of 15 items (BNT-15), will be used to assess language function. The test comprises images ranging from commonly recognized objects to those that are progressively more difficult to identify. Participants are asked to name the object depicted in each image. If the participant is unable to provide the correct name (e.g., "pelican"), semantic or phonemic cues (e.g., "it is a bird," "pe…") may be provided. The examiner records the type and number of cues required and whether they lead to a correct response. Each correct response is scored as 1 point. The maximum possible score is 15 points, with higher scores indicating better language performance.
Time frame: Day 1
Memory Assessed by the Rey Auditory Verbal Learning Test
The Rey Auditory Verbal Learning Test (RAVLT) will be used to assess memory. This test evaluates verbal learning, immediate verbal memory, susceptibility to interference, free recall, and recognition memory. Scoring is based on the number of correctly recalled words in each trial, delayed recall performance, and the number of correctly rejected distractor items during the recognition phase. Higher scores across all indices indicate superior verbal learning and memory capacity, while significant discrepancies between immediate and delayed recall may suggest retrieval or storage deficits.
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Time frame: Day 1
Visuospatial Function Assessed by the Benton Judgment of Line Orientation Test
The Benton Judgment of Line Orientation Test (JLOT), will be used to assess visuospatial function. The primary aim of the test is to evaluate the individual's ability to perceive, organize, and relate elements within a visual stimulus according to their spatial orientation. The test consists of 30 items, and task difficulty increases progressively as the line segments are shortened from the top or bottom. Scoring is based on paired responses; a point is awarded only if both lines in a pair are correctly identified. Higher scores indicate superior visuospatial perception and spatial relation skills, whereas lower scores may reflect impairments in right-hemisphere mediated spatial organization.
Time frame: Day 1
Executive Function Assessed by the Stroop Test (Çapa Version)
The Stroop Test (Çapa Version) will be used to assess executive functions. This test evaluates selective attention, response inhibition, cognitive flexibility, and information processing speed. The test consists of two stimulus cards. The first card includes 60 colored rectangles (red, green, and blue) arranged in six rows of ten items each. The second card contains color words printed in incongruent ink colors in the same format. For each stage, completion time is recorded in seconds using a digital stopwatch, while the number of errors and self-corrections is recorded as counts. The "interference resistance" time (Stroop D) is calculated in seconds using the formula: Stroop D = Stroop C - Stroop B
Time frame: Day 1
Attention Assessed by the Digit Span Test
The Digit Span Test, a subtest of the Wechsler Memory Scale-Revised, is used to assess attention and concentration. It consists of two components: forward digit span and backward digit span, each associated with different cognitive processes. The scoring was determined by the longest sequence of digits correctly repeated in at least one of the two trials for each level. The maximum attainable span length was 7 for the forward condition and 6 for the backward condition. Based on established norms, the lower limits for normal function were defined as a span of 6 for forward and 4 for backward sequences. The difference between forward and backward digit span should not exceed two digits. Higher scores represent superior working memory and attentional performance.
Time frame: Day 1
Analysis of Spatiotemporal Gait Parameters Under Dual-Task Conditions
Spatiotemporal gait parameters and variability measures will be assessed using the SensorMedica FreeMed baropodometric platform. Within the scope of gait analysis, each participant will first be asked to walk at a self-selected comfortable speed without any dual-task condition, and baseline spatiotemporal parameters will be recorded. Subsequently, gait will be assessed under predefined cognitive dual-task conditions. In this study, participants will be instructed to walk continuously on the platform without stopping, completing at least 40 steps. To ensure a detailed gait analysis, the following parameters will be recorded and reported independently: Step length (cm), step width (cm), cadence (steps/min), step cycle duration (s), stance and swing phase durations (% of gait cycle), single and double support times (s), and gait variability (CV%). Multiple units will be reported for each specific gait sub-parameter as detailed in the description.
Time frame: Day 2
Cognitive Dual-Task Gait Protocol
This study evaluates gait performance under five cognitive dual-task conditions targeting language, memory, attention, visuospatial, and executive functions in Parkinson's disease (PD). Tasks were developed based on standardized neuropsychological tests, including the Boston Naming Test, Rey Auditory Verbal Learning Test, Benton Judgment of Line Orientation, Digit Span, MoCA, and Stroop Test. Participants walk at a self-selected pace on a gait platform under seven conditions: single-task, five cognitive dual-tasks, and a motor dual-task. In the single-task condition, participants walk at a comfortable speed. Language tasks involve naming images; memory tasks require recalling word lists; visuospatial tasks involve identifying line orientations; executive tasks require naming ink color of incongruent words; attention tasks involve repeating digit sequences. In the motor task, participants walk while carrying a glass of water.
Time frame: Day 2
Movement Disorder Society-Unified Parkinson's Disease Rating Scale Part III: Motor Examination (MDS-UPDRS III)
The severity of motor symptoms in patients with Parkinson's disease (PD) will be assessed using Part III (Motor Examination) of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS). The MDS-UPDRS consists of four parts. Part I evaluates non-motor experiences of daily living with 13 items, while Part II assesses motor experiences of daily living, also consisting of 13 items. Part III focuses on motor examination and includes 18 items assessing motor symptoms. Part IV consists of 6 items evaluating motor complications related to treatment. Each item in the scale is scored on a 5-point Likert scale ranging from 0 to 4, where 0 = normal, 1 = slight, 2 = mild, 3 = moderate, and 4 = severe. In this study, Parts I, III, and IV will be used to obtain descriptive clinical data for individuals with PD.
Time frame: Day 1
Anxiety and Depression Assessed by the Hospital Anxiety and Depression Scale
Since anxiety and mood status may influence gait performance, these factors will be evaluated. For this purpose, the Hospital Anxiety and Depression Scale (HADS) will be used. The HADS consists of 14 items and includes two subscales: anxiety (HADS-A) and depression (HADS-D). Each subscale yields scores ranging from 0 to 21. The cut-off points for the Turkish version are 10 for the anxiety subscale (HADS-A) and 7 for the depression subscale (HADS-D).
Time frame: Day 1
Static Balance Assessed by the SensorMedica FreeMed Device
Static balance analysis will be performed using the SensorMedica FreeMed (FreeMed, SensorMedica, Rome, Italy) device. The system will be calibrated prior to each assessment. Before testing, participants will be informed about the test procedures. All assessments will be conducted with participants barefoot. Prior to the measurements, participants will be instructed to stand upright, look at a fixed point in front of them, and distribute their body weight evenly on both feet in order to align their center of mass along the midline. For this purpose, participants will be asked to position the point representing their center of pressure, displayed on the device screen, within the marked central cross area on the platform. During the tests, participants will be instructed not to lift or move their feet. Measurements will be performed twice under both eyes-open and eyes-closed conditions, and the mean values will be used for analysis.
Time frame: Day 2
Dual-Task Cost
An individual's capacity to perform a dual task is defined as dual-task performance. To determine the impact of dual-task conditions on performance, dual-task cost is calculated using measures such as task accuracy and the time required to complete the dual task. Dual-task cost is expressed using the following formula: Dual-Task Cost = \[(Dual-Task Performance - Single-Task Performance) / Single-Task Performance\] × 100
Time frame: Day 2