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The Sensorimotor Locus of Balance Control in Elderly Gait

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ClinicalTrials.gov Identifier: NCT03341728
Recruitment Status : Recruiting
First Posted : November 14, 2017
Last Update Posted : November 14, 2017
Sponsor:
Collaborator:
National Institute on Aging (NIA)
Information provided by (Responsible Party):
University of North Carolina, Chapel Hill

Brief Summary:
The aging population is at an exceptionally high risk of debilitating falls, contributing significantly to reduced independence and quality of life. It remains extremely challenging to screen for falls risk, and programs designed to mitigate falls risk have only modestly influenced the sizeable portion of the aging population experiencing one or more falls annually. Balance control in standing and walking depends on integrating reliable sensory feedback and on planning and executing appropriate motor responses. Walking balance control is especially dynamic, requiring active and coordinated adjustments in posture (i.e., trunk stabilization) and foot placement from step to step. Accordingly, using a custom, immersive virtual environment, the investigators have shown that sensory (i.e., optical flow) perturbations, especially when applied during walking, elicit strong and persistent motor responses to preserve balance. Exciting pilot data suggest that these motor responses are remarkably more prevalent in old age, presumably governed by an increased reliance on vision for balance control. Additional pilot data suggest that prolonged exposure to these perturbations may effectively condition successful balance control strategies. Founded on these recent discoveries, and leveraging the increase reliance on vision for balance control in old age, the investigators stand at the forefront of a potentially transformative new approach for more effectively identifying and mitigating age-related falls risk. The investigator's overarching hypothesis is that optical flow perturbations, particularly when applied during walking, can effectively identify balance deficits due to aging and falls history and can subsequently condition the neuromechanics of successful balance control via training.

Condition or disease Intervention/treatment Phase
Ambulation Difficulty Gait, Unsteady Fall Position Sense Disorders Behavioral: Optical flow perturbations Not Applicable

Detailed Description:

Specific Aim 1. Investigate sensory, motor, and cognitive-motor mechanisms governing susceptibility to optical flow perturbations. Aging increases the reliance on vision for balance control. However, central and peripheral mechanisms underlying aging and falls history effects on the susceptibility to optical flow perturbations are unclear. Hypothesis 1: Entrainment to optical flow perturbations will correlate most strongly with visual dependence and decreased somatosensory function, alluding to an age-associated process of multi-sensory reweighting. Methods: Multivariate models will quantify the extent to which strategically-selected sensory (i.e., visual dependence via rod/frame test, somatosensory function), motor (i.e., rate of torque development, timed sit-to-stand) and cognitive-motor (i.e., interference) mechanisms underlie inter-individual differences in susceptibility to perturbations.

Specific Aim 2. Estimate the efficacy of prolonged optical flow perturbations to condition the neuromechanics of walking balance control in older adult fallers. Pilot data from young adults suggests that prolonged exposure to optical flow perturbations may condition reactive strategies used to successfully control walking balance. The investigator's premise is that dynamic perturbation training can improve resilience to unexpected balance disturbances. Here, the investigators conduct a preliminary test of the effects of training with optical flow perturbations on walking balance in older adult fallers. Hypothesis 2: (a) Older adults with a history of falls will adapt to prolonged exposure to perturbations, conditioning their step to step adjustments in walking balance control, and (b) improving their response to unexpected balance challenges following training. Methods: In two 20 min sessions, on different days in a randomized cross-over design, older adults with a history of falls will walk with ("treatment" session) and without ("control" session) prolonged exposure to optical flow perturbations. The investigators will assess time-dependent changes in the neuromechanics of walking balance during training and after-effects via gait variability, dynamic stability, and performance on a series of real-world like targeting and obstacle avoidance tasks.


Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 32 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Intervention Model Description: In two 20 min sessions, on different days in a randomized cross-over design, older adults with a history of falls will walk with ("treatment" session) and without ("control" session) prolonged exposure to optical flow perturbations.
Masking: None (Open Label)
Masking Description: No Masking
Primary Purpose: Treatment
Official Title: The Sensorimotor Locus of Balance Control in Elderly Gait
Actual Study Start Date : October 30, 2017
Estimated Primary Completion Date : August 30, 2018
Estimated Study Completion Date : August 30, 2018

Arm Intervention/treatment
Experimental: Older Fallers
Older adults with a history of falls will walk during exposure to optical flow perturbations
Behavioral: Optical flow perturbations
Continuous mediolateral (i.e., side-to-side) 20-minute perturbations of optical flow that elicit the visual perception of lateral imbalance via virtual reality.

Experimental: Older Non-Fallers
Older adults without a history of falls will walk during exposure to optical flow perturbations
Behavioral: Optical flow perturbations
Continuous mediolateral (i.e., side-to-side) 20-minute perturbations of optical flow that elicit the visual perception of lateral imbalance via virtual reality.




Primary Outcome Measures :
  1. Change in Postural Sway after 10 min of walking [ Time Frame: Baseline, 10 minutes ]
    magnitude of side-to-side postural sway

  2. Change in kinematic variability after 10 min of walking [ Time Frame: Baseline, 10 minutes ]
    Magnitude of step-to-step corrections

  3. Change in foot placement targeting accuracy after 10 min of walking [ Time Frame: Baseline, 10 minutes ]
    Accuracy of performing foot placement targeting task. i.e., distance between heel marker at initial contact and target line (measured using three-dimensional motion capture during walking).


Secondary Outcome Measures :
  1. Change in cognitive-motor interference accuracy after 10 min of walking [ Time Frame: Baseline, 10 minutes ]
    Accuracy performing an auditory stroop test (cognitive dual-task)

  2. Change in cognitive-motor interference response time after 10 min of walking [ Time Frame: Baseline, 10 minutes ]
    Response time in performing an auditory stroop test (cognitive dual-task)



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Ages Eligible for Study:   65 Years and older   (Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Be able to walk without an assistive aid (i.e., walker, cane)
  • Have the full capacity to provide informed consent

OLDER NON-FALLERS

  • Age 65+ years
  • No history of falls* in the prior 12 months

OLDER ADULTS WITH A HISTORY OF FALLS

  • Age 65+ years
  • History of one or more falls* in the prior 12 months

    • For the purposes of this study, falls counted towards the self-reported total will be defined as per the Kellogg International Work Group - a fall is "unintentionally coming to the ground or some lower level and other than as a consequence of sustaining a violent blow, loss of consciousness, sudden onset of paralysis as in stroke or an epileptic seizure"

Exclusion Criteria:

  • Current lower extremity injury or fracture
  • Taking medication that causes dizziness
  • Have a leg prosthesis
  • Prisoners
  • Individuals clearly lacking the capacity to provide informed consent

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03341728


Contacts
Contact: Jason R Franz, PhD (919)966-6119 jrfranz@email.unc.edu

Locations
United States, North Carolina
Applied Biomechanics Laboratory Recruiting
Chapel Hill, North Carolina, United States, 27514
Contact: Jason Franz, Ph.D.    919-966-6119    jrfranz@email.unc.edu   
Sponsors and Collaborators
University of North Carolina, Chapel Hill
National Institute on Aging (NIA)
Investigators
Principal Investigator: Jason Franz, PhD Unviersity of North Carolina at Chapel Hill

Additional Information:
Publications of Results:
Responsible Party: University of North Carolina, Chapel Hill
ClinicalTrials.gov Identifier: NCT03341728     History of Changes
Other Study ID Numbers: 15-2267
R56AG054797-01A1 ( U.S. NIH Grant/Contract )
First Posted: November 14, 2017    Key Record Dates
Last Update Posted: November 14, 2017
Last Verified: November 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Plan Description: There is no plan to share IPD with other researchers.

Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No

Additional relevant MeSH terms:
Gait Disorders, Neurologic
Mobility Limitation
Somatosensory Disorders
Neurologic Manifestations
Nervous System Diseases
Signs and Symptoms
Sensation Disorders