# Optimizing transcranial direct current stimulation (tDCS) to improve dual task gait and balance in older adults

> **NIH NIH R21** · HEBREW REHABILITATION CENTER FOR AGED · 2020 · $180,941

## Abstract

Project Summary: Standing and walking are almost always completed in unison with other cognitive tasks
such as talking, reading or making decisions. The ability to perform this important type of “dual tasking” is
critical to daily activities and dependent upon one’s capacity to effectively activate appropriate brain networks
that include the left dorsolateral prefrontal cortex (dlPFC). Transcranial direct current stimulation (tDCS) is a
safe, noninvasive technology that can selectively modulate brain excitability (i.e., the likelihood of activation) by
passing low-level currents between electrodes placed upon the scalp. We have demonstrated through a series
of studies that a single, 20-minute exposure of tDCS targeting the left dlPFC—administered via two large
sponge electrodes—reduces dual task costs to metrics of standing postural control and gait, when tested
immediately following stimulation. Still, we and others have also observed relatively high between-subject
variability in the effects of this ‘traditional’ bipolar form of tDCS. We contend that this variability in effectiveness
arises in part from relatively diffuse and unspecific current flow when using large sponge electrodes, in
combination with individual variability in head and brain anatomy that significantly alters current flow and the
generated electric field in the target brain region. In this project, we will apply recent advances in tDCS
modeling and administration to 1) model the electric fields generated by traditional tDCS in older adults using
their individual structural brain MRIs, and 2) develop personalized tDCS—delivered via an array of eight small
gel electrodes—by using optimization algorithms to determine electrode placement and current parameters
needed to generate desired electrical field with the brain region of interest. Our Specific Aim is to examine the
immediate after-effects of personalized tDCS, traditional tDCS, and sham stimulation on dual task standing
and walking in older adults. Our study population will be older men and women without overt disease or illness,
yet with poor baseline dual task performance defined as a dual task cost (i.e., reduction) to gait speed of at
least 20% induced by simultaneously performing a serial subtraction task when walking. We hypothesize that
across participants, the effect of traditional tDCS on dual task standing and walking performance will correlate
with a specific component of the electric field generated over the left dlPFC target. We also hypothesize that
personalized tDCS will induce A) greater effects on dual task standing and walking performance as compared
to traditional tDCS and sham stimulation, and B) these effects will be more consistent across individuals as
compared to traditional tDCS. This project will provide important insights into tDCS “dosage” that will enable us
and many other researchers to better understand, control, and optimize this form of noninvasive brain
stimulation to individual head and b...

## Key facts

- **NIH application ID:** 9982164
- **Project number:** 5R21AG064575-02
- **Recipient organization:** HEBREW REHABILITATION CENTER FOR AGED
- **Principal Investigator:** Bradley D. Manor
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $180,941
- **Award type:** 5
- **Project period:** 2019-08-01 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9982164

## Citation

> US National Institutes of Health, RePORTER application 9982164, Optimizing transcranial direct current stimulation (tDCS) to improve dual task gait and balance in older adults (5R21AG064575-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/9982164. Licensed CC0.

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