Overview
The primary objective of this new line of research is to test whether augmenting sensory information from the legs, using Walkasins sensory neuroprosthesis, can enhance performance of a complex walking task in older adults with foot sensory impairment. The overarching hypothesis is that Walkasins will enhance the automaticity and reduce cognitive demand of walking in older adults with foot sensory impairments, as measured by reduced prefrontal activity, decreased dual-task costs, and lower gait variability.
Description
Preserving mobility function in older adults is crucial for ensuring safe walking in complex environments, including home and community settings. A common example is navigating a busy street with obstacles like uneven sidewalks and pedestrians, or a home with furniture, stairs, and narrow hallways, all while engaging in a conversation or mental task. Such environments create a potential risk for older adults, who may show declines in function across multiple systems, including sensation, cognition, and mobility. Successfully walking in complex environments depends on cognitive control processes, such as attention and motor planning, which rely on sufficient sensory information from peripheral receptors. Somatosensory impairment, particularly in the feet, is common among older adults and tends to increase progressively with age, often worsened by the presence of certain diseases. Age-related somatosensory impairments disrupt essential input to central motor and cognitive networks, raising the risk of accidental collisions, slips, trips, and injurious falls. Older adults may compensate by increasing cognitive load (attention and executive control of movement). However, this shift may overburden cognitive systems, again raising the risk of collisions, slips, trips, and falls. There is a critical, yet underexplored, need to restore somatosensory input to the nervous system during walking in older adults with foot sensory impairments. Therefore, the objective of this study is to investigate whether the use of a novel lower-limb sensory prosthesis, Walkasins, improves complex walking performance and reduces cognitive load. This crossover study will enroll 30 participants with foot sensory impairment, who will undergo complex walking performance assessments while wearing the Walkasins in both the "on" and "off" settings. These settings will be assessed in separate visits occurring at least one week apart, to allow for a washout period. The walking course will use a pressure-sensitive instrumented walkway to analyze kinetic and kinematic variability of the gait pattern. These assessments will include typical walking, as well as dual-task walking with and without obstacle crossing as a behavioral assessment of cognitive load. Furthermore, cognitive load will be assessed by measuring prefrontal cortical activity with functional near infrared spectroscopy (fNIRS). We will address the following specific aims:
Specific Aim 1 is to test whether Walkasins can improve walking performance, hypothesizing greater reductions in dual-task costs and gait variability when using Walkasins in the "on" setting compared to the "off" setting.
Specific Aim 2 is to assess the potential of Walkasins to reduce cognitive load during walking, hypothesizing lower prefrontal cortical activity when using Walkasins in the "on" setting compared to the "off" setting.
This pilot study enhances our understanding of age-related sensory impairments in neural control and walking performance and will prepare us for larger-scale trials with more intervention sessions, larger sample sizes, and a focus on the underlying neurophysiological mechanisms. This study and future research contribute to the development of rehabilitation strategies that support healthy aging and enhance functional mobility.
Eligibility
Inclusion Criteria:
- Not having any significant existing medical conditions, historical health issues, or medications (outlined in the exclusion criteria table above) that could impede the execution of the walking task and assessment.
- age 65 - 95.
- no severe high blood pressure (systolic < 180 mmHg and/or diastolic < 100 mmHg at rest).
- no severe vision impairment: visual acuity ≥ 20/70 as determined by Snellen eye chart.
- slow walking speed: preferred walking speed slower than 1.0 m/s over 10 meter.
- no cognitive impairment: Montreal Cognitive Assessment (MoCA) score ≥ 26 out of 30 possible points.
- foot sensory impairment: Inability to feel the 10 g monofilament at ≥1 of 10 tested sites on either foot is considered a sign of impaired protective sensation. loss.
Exclusion Criteria:
- diagnosed neurological disorder or injury of the central nervous system, or observation of symptoms consistent with such a condition (Alzheimer's, Parkinson's, stroke, etc.)
- severe arthritis, such as awaiting joint replacement
- current cardiovascular, lung or renal disease; untreated diabetes; terminal illness
- myocardial infarction or major heart surgery in the previous year
- cancer treatment in the past year, except for nonmelanoma skin cancers and cancers having an excellent prognosis (e.g., early stage breast or prostate cancer)
- current diagnosis of schizophrenia, other psychotic disorders, or bipolar disorder
- currently taking medications that affect the central nervous system, such as benzodiazepines, anti-cholinergic medication, and GABAergic medication, among others
- no severe vision impairment (visual acuity ≥ 20/70 as determined by Snellen eye chart)
- uncontrolled hypertension at rest (systolic > 180 mmHg and/or diastolic > 100 mmHg)
- bone fracture or joint replacement in the previous six months
- current enrollment in any other clinical trial
- planning to relocate out of the area during the study period
- non-English* speaking, due to the likelihood of difficulties following instructions and communicating remotely
- clinical judgment of the investigative team