Brain Stimulation for Foot-sole Sensation in Older Adults With Foot-sole Somatosensory Deficits (BSFS)

Cortical Mechanisms and Modulation of Somatosensation in Older Adults With Foot Sole Somatosensory Impairments

In older adults, diminished sensation of the legs and feet is highly prevalent and causes poor balance and reduced mobility. This type of sensation is not only dependent upon the receptors and nerves in the legs and feet, but also upon a complex central nervous system pathway that includes the cerebral cortex of the brain. This project will use a form of noninvasive brain stimulation called transcranial direct current stimulation (tDCS) to test whether increasing the excitability of the brain networks that process sensory feedback can augment foot sole sensation, balance, and mobility in older adults suffering from mild-to-moderate foot sole sensory impairments.

Study Overview

• Status: Recruiting
• Conditions: Mobility; Somatosensory Function; Balance Control
• Intervention / Treatment: Device: transcranial direct current stimulation; Device: active sham stimulation

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Junhong Zhou, PhD; Phone Number: 617-971-5346; Email: junhongzhou@hsl.harvard.edu

Study Locations

• United States
  • Massachusetts
    • Roslindale, Massachusetts, United States, 02131
      • Recruiting
      • Hebrew SeniorLife
      • Contact: Kathy Tasker; Phone Number: 617-971-5351; Email: KathyTasker@hsl.harvard.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Aged ≥65 years.
2. Self-reported feeling of unsteadiness or difficulty when standing and walking.
3. Mild-to-moderate foot-sole somatosensory impairment: the ability to perceive 75g monofilament but inability to perceive 10g monofilament.

Exclusion Criteria:

1. self-reported inability to stand or walk continuously for one minute without personal assistance (canes or walkers allowed);
2. history or presence of foot ulceration, amputation, or deformities;
3. self-reported uncontrolled pain or pain that is associated with mobility disability;
4. uncontrolled diabetes mellitus;
5. hospitalization within the past three months due to acute illness, or as the result of a musculoskeletal injury significantly affecting balance;
6. persistent severe pain of lower extremity when standing or walking;
7. diagnosis of dementia, Parkinson's disease, or stroke that affects balance;
8. unstable medical condition;
9. legal blindness or deafness;
10. uncontrolled hypertension (i.e., systolic BP >180, diastolic BP >100 mm Hg, or prescription of ≥3 anti-hypertensive medications);
11. functionally limiting nephropathy, severe diseases or transplant of the kidney or liver, renal or congestive heart failure;
12. active cancer treatment;
13. balance disorders due to past use of chemotherapy or history of Guillain-Barré syndrome;
14. use of neuro-active or recreational drugs (e.g., sedatives, anti-psychotics), or alcohol abuse, which may affect the brain excitability;
15. contraindications to MRI or tDCS (e.g., personal or family history of seizures or epilepsy, metallic or electric bio-implants, claustrophobia, brain surgery);
16. persistent vertigo;
17. history of Charcot-Marie-Tooth nerve disease.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: tDCS group; Participants in this arm will receive the real tDCS intervention.	Device: transcranial direct current stimulation; tDCS can safely and selectively modulate cortical excitability (specifically neuronal firing likelihood) by transferring weak electrical currents between scalp electrodes. The direct current delivered by any one electrode will not exceed 2.0 mA and the total amount of current from all electrodes will not exceed 4 mA in this study.
Sham Comparator: sham group; Participants in this arm will receive the sham stimulation as control.	Device: active sham stimulation; sham stimulation will implement the same protocol of the tDCS intervention; however, only very low-level currents (no more than 0.5 mA) are transferred between the same electrodes used for the tDCS throughout the 20-minute session. This strategy effectively mimics the cutaneous sensations and skin redness induced by creating only micro cortical electric fields.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
postural sway area when standing with eyes closed on the foam	This metric assesses the degree to which the soft support and cut-off of the vision diminishes the control of standing posture.	Before and immediately after intervention
Timed Up-and-Go (TUG) time	This metric assesses mobility.	Before and immediately after intervention
Standing vibratory thresholds of each foot sole	This metric assesses the degree to which the foot soles can sense the vibro-tactile stimuli when standing.	Before and immediately after intervention
On-target Blood oxygen level dependent (BOLD) signal intensity in response to foot sole stimulation	This metric assesses the degree to which brain cortical regions activated by the walking-related foot-sole stimulation.	Before and immediately after intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postural sway speed when standing with eyes closed on the foam	This metric assesses the degree to which the soft support and cut-off of the vision diminishes the control of standing posture.	Before and immediately after intervention
Gait speed of 10m walking test	This metric assesses mobility.	Before and immediately after intervention

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
BOLD signal intensity within other relevant cortical regions in response to foot sole stimulation	This metric assesses the degree to which brain cortical regions activated by the walking-related foot-sole stimulation.	Before and immediately after intervention

Collaborators and Investigators

• Sponsor: Hebrew SeniorLife
• Collaborators: National Institute on Aging (NIA)

Study record dates

Study Major Dates

• Study Start (Actual): February 26, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: January 8, 2025
• First Submitted That Met QC Criteria: January 8, 2025
• First Posted (Actual): January 13, 2025

Study Record Updates

• Last Update Posted (Actual): April 22, 2026
• Last Update Submitted That Met QC Criteria: April 21, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: brain stimulation; balance and mobility; foot-sole somatosensory function
• Additional Relevant MeSH Terms: Therapeutics; Behavioral Disciplines and Activities; Electric Stimulation Therapy; Convulsive Therapy; Psychiatric Somatic Therapies; Electroshock; Psychological Techniques; Transcranial Direct Current Stimulation
• Other Study ID Numbers: Pro00044674; K01AG075180 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No