The Effects of Dual Task Training on Motor and Non-Motor Function in Individuals With Parkinson's Disease
Phase: NA
Conditions: Parkinson's Disease
Sponsor: The Cleveland Clinic

 
Last Modified 9/6/16 
 
The Effects of Dual Task Training on Motor and Non-Motor Function in Individuals with Parkinson’s 
Disease 
NCT02538029 
9.6.16

 
Last Modified 9/6/16 
 
Rationale and Impact: Activities of daily living often require the ability to dual task (DT), or 
simultaneously perform two attention-demanding motor or cognitive tasks.  The ability to perform DT 
activities, in particular tasks that require a level of postural stability, is a fundamental problem for 
individuals with Parkinson’s disease (PD).1-5  Under DT constructs, individuals with PD typically 
exhibit a “posture second” strategy, where inadequate attention is allocated to gait and postural 
stability when challenged with a secondary task.1  In contrast, young and healthy older adults exhibit a 
“posture first” strategy by prioritizing gait and balance over the cognitive task.1  The “posture second” 
prioritization observed in PD may be a result of decreased attentional flexibility; thus when two tasks 
require concomitant attention, individuals with PD do not have the attentional flexibility to 
simultaneously attend to both tasks while controlling for motor deficits due to basal ganglia 
pathology.2,6,7  Hence, DT situations lead to increased loss of balance and falls in the PD population 
compared to their age-matched healthy peers.3  While these DT deficits in individuals with PD have 
been noted throughout the literature, there is a fundamental gap in understanding if DT deficits can be 
minimized through a behavioral intervention.     
 
Single task (ST) training, defined as performing a motor or cognitive task in isolation, does not 
improve DT performance.8  DT deficits can be minimized in older adults through DT exercise 
interventions, which range from seated exercises to treadmill training with concurrent cognitive tasks.8  
Several studies noted improvements in gait speed during DT constructs after DT specific training.9,10  
DT training programs have also demonstrated the ability to improve spatiotemporal characteristics of 
gait, cognitive performance, clinical measures of balance, and quality of life measures in older adults 
with a history of falls.11  These DT therapeutic approaches have not been systematically evaluated in 
PD patients.    
 
Individuals with PD demonstrate deterioration in stride length, step width, step variability, and 
walking speed in DT situations compared to performing walking alone.2  Although the literature is 
sparse, the feasibility of implementing a DT training program has been investigated for individuals 
with PD, with results indicating efficacy through improvements in gait speed during DT 
conditions;12,13 however, changes in non-motor outcomes have not been well documented.  
Additionally, it is not known how specific cognitive constructs affect gait.  Stegemoller and colleagues 
suggested that cognitive processing speed correlated with stride length and walking speed, executive 
function correlated with step length variability, and that there were no significant associations with 
working memory for individuals with PD.2  However, 
these individuals performed the gait testing and 
cognitive testing separately, so it is not known what 
occurs when these tasks are performed simultaneously.   
 
Biomechanical systems, such as virtual reality 
(VR) training, used to assess and treat gait deficits and 
concomitantly provide a secondary motor or cognitive 
are promising treatment interventions for individuals 
with PD.14,15   We propose that VR training may offer 
insight into the mechanism of DT deficits.  Dr. Albert’s 
lab owns the one of two non-military installation of the 
Computer Assisted Rehabilitation Environment 
(CAREN), a VR reality system with a fully integrated 
3-D motion capture system, a surround projection 
screen, dual belt treadmill with 6 degrees of freedom 
movable platform, two force platforms, a safety 
harness, and programmable software that can be used to create a variety of interactive modules (Figure 
1).  The interactive modules create either game-like or real-world environments that allow therapists to 
challenge the participant by altering either motor demands (e.g. virtual curbs, variations in walking 
Figure 1: Module of wooded path on CAREN system.  The 
treadmill (outlined in red) in front of the projection screen allows 
the individual feel like they are part of the scene.   

 
Last Modified 9/6/16 
 
surface, uneven surfaces) or cognitive demands (e.g. memory, attention, executive function) in a safe 
environment.  The CAREN system is unique from other experimental environments due to the ability 
to create real-world environments (e.g. street scene with pedestrian and vehicle traffic, trail walking) in 
which the motor and cognitive aspects of function can be systematically manipulated and measured.   
One of the greatest barriers to DT training is the lack of knowledge about effective clinical 
interventions.8  The clear benefit to this highly-advanced system is opportunity to investigate 
mechanisms of dual tasking deficits in a given environment.  For example, if participants with PD 
exhibit increased step variability and decreased stride length during visual memory cognitive tasks that 
are not seen during verbal memory cognitive tasks, this would provide valuable insight into task 
selection during a clinical intervention.   
The primary aim of the proposed project is to characterize DT deficits to improve motor, 
cognitive, and quality of life outcomes in individuals with PD.  A single center study is outlined in 
Figure 2.  Phase 1 of the intervention will involve an in-depth gait analysis on 15 individuals with PD.  
The purpose of Phase 1 is to generalize characteristics of gait and postural control during specific DT 
conditions, as in the example provided above.  Phase 2 (N=20) involves the clinical translation of these 
findings.  This phase will involve creating a clinical intervention based on the objective information 
gathered from the CAREN system.  Researchers will use the biomechanical data gathered from the 
CAREN system to prioritize interventions based on given gait and postural control deviations during 
DT interventions.  To continue with the above example, if we find that visual memory tasks lead to 
decreased stride length, then the therapeutic intervention would be a task such as targeted stepping 
during gait (e.g. placing stickers slightly wider than normal step length on a treadmill) while 
performing various visual memory tasks.  The intervention will take place 3x/week for a total of 8 
weeks.  Interventional groups will include: 1) DT clinical group (N=10) and 2) Single task group 
(N=10).  ST training will serve as a control group.8    
 
Specific Aims: 
Aim 1: To categorize gait and balance deficits during DT constructs in individuals with PD.   
A three-dimensional (3-D) gait analysis using the CAREN system will be used during ST (walking 
alone) and DT conditions which consist of walking and completing tasks in the following cognitive 
domains: processing speed, visual memory, verbal memory, executive function, and attention (See 
Table 1 for cognitive tasks).  Specifically, the CAREN gait analysis will examine spatiotemporal 
parameters of gait along with gait variability and joint angles.  Additionally, a limit of stability (LOS) 
test will be conducted during ST and DT conditions.        
Hypothesis: Gait parameters and LOS will be impaired under DT conditions compared to ST.     
 
Aim 2: To create and pilot a DT clinical intervention based on biomechanical analysis from the 
CAREN system that improves motor and non-motor function of individuals with PD. 
Primary motor outcome will include a 3-D gait analysis using the same parameters at stated in Aim 1.  
Secondary clinical motor outcome include distance walked during the 2 Minute Walk Test (2MWT) 
under ST and DT conditions.  The Quality of Life in Neurological Disorders (Neuro-QOL) 
questionnaire will be administered as a quality of life measure.  Fall risk will be assessed through the 
Activities-specific Balance Confidence (ABC) Scale.  Cognitive measures, motor, and non-motor tests 
are described in Table 1.   

 
Last Modified 9/6/16 
 
Hypothesis: The DT clinical group will demonstrate the greater improvements in motor and non-motor 
function compared to the ST groups.   
 
Research Plan: A total of 15 individuals 
diagnosed with idiopathic PD will be included in 
the initial gait analysis to categorize gait and 
postural control deficits associated with DT 
constructs (Figure 2).  During Phase 1, all 
interventions will be carefully documented in 
order to attribute changes in gait parameters of 
postural stability with a domain of cognitive 
function.  Phase 2 of the study (N=20) will 
randomize participants into two groups: 1) DT 
clinical and 2) ST (Figure 2).  Both groups will 
receive a time-matched intervention, 3x/week for a 
total of 8 weeks.  If an individual misses a session, 
he/she will be required to make it up on a different 
day of the same week or at the end in order for all 
24 sessions to be complete.  The entire 
intervention must be completed within a 10 week 
period.  Intervention sessions for all groups will be 
completed under the guidance of a physical or 
occupational therapist who specializes in 
neurological rehabilitation.    Outcome measures 
for Phase 2 will be administered at baseline, end of 
treatment (EOT), and EOT+4 weeks (EOT+4) by a 
blinded evaluator.  The purpose of the EOT+4 
testing is to gauge the permanence of the training intervention.  All participants will be asked to wear a 
wrist-worn activity monitor that will measure steps/day throughout the duration of Phase 2 
participation (baseline through EOT+4). 
Motor, cognitive, and quality of life measures selected are described in Table 1.  The Movement 
Disorder Society - Unified Parkinson’s disease Rating Scale (MDS - UPDRS) will be taken at the 
beginning of both Phase 1 and 2 for demographic data.  Notably, cognitive tasks that are used for 
baseline and EOT evaluation will NOT be used during the intervention to ensure that a learning 
effect is not present. Participants will take their PD medication as prescribed for all testing and 
interventions.  If a participant has a life event (vacation, doctor’s appointment, etc.) where they must 
miss a session, they will be permitted to make up the session.  The total intervention duration cannot 
exceed 12 weeks from the date of the first intervention session.   
 
  
Dual Tasking Clinical (DT clinical): Upon completion of Phase 1 of the study, a protocol for DT 
clinical training will be created based on the interventional gait analyses during various DT conditions.  
The DT clinical group will train in a traditional clinical rehabilitation environment.  A variety of 
motor-cognitive or motor-motor tasks will be administered during balance and gait training (treadmill 
or over ground).  Cognitive tasks will include processing speed, attention, memory, cognitive 
flexibility, and executive function tasks.  Depending on the results of Phase 1, examples of a motor-
cognitive tasks involving verbal memory may include recounting what he/she ate for breakfast this 
morning while navigating an obstacle course.  Tasks will be graded based on the participant’s baseline 
level of motor and cognitive function. The purpose of this group is to determine if a clinical 
Figure 2: Study Flow Chart 

 
Last Modified 9/6/16 
 
intervention based on a biomechanical outcome is feasible and efficacious.  The intervention will last 
approximately 45 min. 
 
Single Task (ST): For this 45 minute session, individuals will perform 1) motor tasks; 2) cognitive 
tasks.  An equal amount of time will be spent on the motor and cognitive tasks.  Each task will be 
performed in a ST construct, where the participant will only have to focus on one task at a given time.  
Examples of ST motor include walking, static and dynamic balance activities such as single-leg stance 
or tandem stance, and reaching in various planes.  Cognitive tasks will be administered with the 
participant in a seated position and include the same cognitive domains: processing speed, visual 
memory, verbal memory, executive function, and attention.   
 
Table 1: Outcome Measures 
Outcome Measure 
Function Evaluated 
Motor Outcomes 
CAREN 3-D gait analysis during ST and 
DT (listed below) conditions to capture  
spatiotemporal gait characteristics 
Objective quantification of gait during ST and DT 
conditions (e.g. step length, gait speed, step 
variability, kinetic and kinematic analysis and 
evaluation of ground reaction forces). 
 
N-back test  
Executive function, attention, and visual memory: 
participant is presented with a visual sequence of 
letters and is required to confirm the letter that is from 
N steps earlier in the sequence. 
 
Stroop test 
A measure of information processing speed; the 
participant is required to name the color that the word 
is printed, not the word itself.  E.g. BLUE  The 
correct response is red. 
 
Repeating digit sequence 
Verbal memory; participant is asked to repeat a string 
of increasingly longer digits 
 
Serial 7s and arithmetic problems 
Mathematical reasoning 
 
Verbal fluency 
Naming as many words as possible beginning with 
the letter “x” 
2 Minute Walk Test (2MWT) under ST 
and DT conditions  
1. ST walking only 
2. DT Motor-Cognitive: 2MWT while 
performing serial 7 countdown 
3. DT Motor-Motor: 2MWT while 
holding a cup of water ¾ full 
Clinical measure of walking endurance both during 
isolated walking and during DT conditions; iPad will 
be worn on a belt on the back to capture asymmetry 
and sway 
Limits of stability (LOS) test in the 
CAREN system (Phase 1) 
Measure of postural control that quantify the 
maximum distance an individual can displace their 
center of mass within their base of support 
Steps per day 
Measure of physical activity behavior 
Non-motor Outcomes 
Quality of Life in Neurological Disorders 
(Neuro-QOL) questionnaire 
Quality of life measure specific to PD 

 
Last Modified 9/6/16 
 
 
Expected Results: We anticipate that both DT and ST groups will improve motor and cognitive 
constructs in ST conditions.   It is anticipated that the DT clinical group will improve compared to the 
ST group in both motor and cognitive performance during DT conditions, quality of life, and fall risk.  
We do not anticipate that DT constructs will change as a result of ST training due to specificity of 
training.8   We anticipate that one of the hallmark findings of this study will be insight to which DT 
constructs result in specific gait and postural control changes.  This will guide clinicians in selecting 
the most appropriate interventions for individuals with PD, and we anticipate this to be the most 
important findings of this study to guide future research and clinical decisions.          
 
Participant Screening: Participants will be pre-screened by the study coordinator.  The following 
inclusion/exclusion criteria will be used: 
 
Inclusion Criteria: 
1. Clinical diagnosis of idiopathic PD 
2. Able to provide informed consent 
3. Ability to ambulate ≥ 300ft with or without an assistive device  
4. Hoehn and Yahr stage 2-4 
5. ≥ 2 fall related to PD in the past 12 months16 
Exclusion Criteria: 
1. Undergone any surgical procedure for the treatment of PD, such as deep brain stimulation 
2. Those who have more than 2 uncontrolled cardiovascular risk factors (uncontrolled heart 
disease, uncontrolled diabetes, etc.) that would qualify them as a high risk exerciser 
3. Musculoskeletal injury or neurological injury other than PD that would restrict physical activity 
4. Inability to follow 2 step commands 
5. Significant cognitive impairment as designated by ≥ 3 errors on the Short Portable Mental 
Status Questionnaire17 
 
Impact on living well with Parkinson’s disease:  From a patient perspective, successful DT 
performance is required to complete most activities of daily living (e.g. looking both ways while 
crossing a street and processing information related to the environment, holding a conversation while 
completing activities of daily living, driving a car in an unfamiliar environment, etc.) and is associated 
with falls,3 thus a DT deficit has a direct impact on quality of life.  Currently, there is uncertainty 
whether rehabilitation specialists should incorporate DT training into a therapeutic exercise program, 
or if clinicians should avoid instructing individuals with PD to simply try to avoid DT activities during 
activities of daily living.18,19  The latter approach is not only impractical but would potentially lead to 
greater isolation for PD patients, which has been shown to have a significant impact on quality of 
life.20  A more empowering and sustainable approach is to better understand the DT declines and 
develop targeted intervention strategies to overcome these declines. The benefits of the DT 
interventions proposed are that they can be administered over a relatively short time period (conducive 
Activities-specific Balance Confidence 
(ABC) Scale 
Measure of confidence performing various activities 
without loss of balance or falls; predictive of 
recurrent falls 
Cognitive measures performed during DT 
training and in a seated position  
Measures cognitive function with and without (in a 
seated position) the coupling motor task 
Tests using an iPad 
Assessing information processing, vision, and balance 
Questionnaires 
Assessing falls, physical activity behavior, and 
quality of life 

 
Last Modified 9/6/16 
 
for third party insurance payment) that is feasible in a clinical setting, and it can be modified by the 
results from high tech (VR) setting.   
 
Novel Aspects of this Project: DT interventions are novel therapeutic interventions for PD.  There are 
no studies that have examined DT interventions with the same rigor as proposed.  This prospective, 
randomized study using a ST group as a time-matched control intervention has the potential to directly 
impact therapeutic treatment of individuals with PD.  In addition, the VR intervention is novel 
technology that has the potential to capture more objective, biomechanical information.  If 
biomechanical data gathered from the CAREN system is able to assist clinicians more appropriately 
select the ideal intervention, this could have an immediate impact on the way that DT is treated in 
individuals with PD.   
 
Data Confidentiality: Study data that will be collected on the CAREN system will be de-identified 
using only the participant's study number.  For purposes of the 3-D motion analysis, participants are 
videotaped; however this video will not leave the computer of the CAREN system without further 
written consent from the participant.  Other outcome measures will be collected on Redcap ®, a secure 
electronic database, where only research study personnel listed on this study submission will have 
access to the study data. Other electronic data will be labeled with only the subject number.  The 
original signed and dated informed consent document along with any paper that may be used for data 
collection will be maintained in a study binder in a locked storage closet within Dr. Alberts' dedicated 
laboratory space in the Walker Building. The regulatory binder for this study will be kept in this same 
location, and only research personnel listed on this study submission will have access to this 
information. 
 
Potential Risks: There are potential risks and discomforts to this study.  There is a risk of muscle 
soreness and fatigue that comes along with exercising.  There is a risk of falls in the clinical and VR 
setting, although in the VR setting participates will wear a harness to prevent falls.  With the markers 
that will be worn for the gait analysis, there is a risk of temporary skin irritation.  Although the 
intensity of exercise will be low, there is a risk of a cardiovascular event.  All exercise personnel will 
be CPR certified and there is a medical emergency team located on site.  There may be other risks with 
this intervention that are not yet known.   
 
 
 
 

 
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