Targeted tDCS Mitigates Dual‐Task Costs to Gait and Balance in Older Adults

Abstract

Objective Among older adults, the ability to stand or walk while performing cognitive tasks (ie, dual‐tasking) requires coordinated activation of several brain networks. In this multicenter, double‐blinded, randomized, and sham‐controlled study, we examined the effects of modulating the excitability of the left dorsolateral prefrontal cortex (L‐DLPFC) and the primary sensorimotor cortex (SM1) on dual‐task performance “costs” to standing and walking. Methods Fifty‐seven older adults without overt illness or disease completed 4 separate study visits during which they received 20 minutes of transcranial direct current stimulation (tDCS) optimized to facilitate the excitability of the L‐DLPFC and SM1 simultaneously, or each region separately, or neither region (sham). Before and immediately after stimulation, participants completed a dual‐task paradigm in which they were asked to stand and walk with and without concurrent performance of a serial‐subtraction task. Results tDCS simultaneously targeting the L‐DLPFC and SM1, as well as tDCS targeting the L‐DLPFC alone, mitigated dual‐task costs to standing and walking to a greater extent than tDCS targeting SM1 alone or sham (p < 0.02). Blinding efficacy was excellent and participant subjective belief in the type of stimulation received (real or sham) did not contribute to the observed functional benefits of tDCS. Interpretation These results demonstrate that in older adults, dual‐task decrements may be amenable to change and implicate L‐DPFC excitability as a modifiable component of the control system that enables dual‐task standing and walking. tDCS may be used to improve resilience and the ability of older results to walk and stand under challenging conditions, potentially enhancing everyday functioning and reducing fall risks. ANN NEUROL 2021;90:428–439

Transcranial Direct Current Stimulation on Different Targets to Modulate Cortical Activity and Dual-Task Walking in Individuals With Parkinson’s Disease: A Double Blinded Randomized Controlled Trial

“…Mishra and Thrasher (2021) also reported that the increase of dual-task gait speed after a single session of DLPFC tDCS was more than Sham tDCS in patients with PD. Similarly, tDCS targeting the DLPFC has been reported to improve dual-task gait performance in older adults and people with stroke (Zhou et al, 2021). In contrast, we previously noted that the dual-task gait training for 12 sessions resulted in a 20% improvement of cognitive dual-task walking speed in people with PD (Yang et al, 2019).…”

Effects of 4 Weeks of High-Definition Transcranial Direct Stimulation and Foot Core Exercise on Foot Sensorimotor Function and Postural Control

“…Moreover, no significant improvements in postural control as induced by HD-tDCS were observed. Although a meta-analysis revealed that tDCS applied over M1 appeared to improve postural control, more recent studies also showed significant effects of tDCS targeting M1 on standing postural control ( de Moura et al, 2019 ; Zhou et al, 2021 ). One possible reason may be that the leg area of M1 is located in parallel to the direction of current flow delivered by tDCS so that only a very small electric field can be generated over M1.…”

“…One possible reason may be that the leg area of M1 is located in parallel to the direction of current flow delivered by tDCS so that only a very small electric field can be generated over M1. Therefore, the excitability of M1 can be increased to a very limited extent, which largely limits the effects of tDCS targeting M1 on standing postural control performance ( Zhou et al, 2021 ). Future studies are highly demanded to optimize the tDCS montages targeting M1 to maximize the activation of this important brain region.…”

Combining Transcranial Direct Current Stimulation With Tai Chi to Improve Dual-Task Gait Performance in Older Adults With Mild Cognitive Impairment: A Randomized Controlled Trial

“…Nevertheless, our study design cannot answer the question of whether multisession a-tDCS coupled with TC would exert additional effects compared to a-tDCS alone. According to another study, tDCS targeting the left DLPFC immediately mitigated dual-task costs to walking ( Zhou et al, 2021 ). Although our experimental design did not include a “tDCS only” group, we may speculate that multisession a-tDCS alone could exert a similar beneficial effect on dual-task gait performance.…”