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.

Ying-Yi Liao,Chi Ieong Lau,Mu-N Liu,Vincent Walsh,Han-Cheng Wang

doi:10.3389/fnagi.2021.766649

Abstract

Introduction: Engaging in a secondary task while walking increases motor-cognitive interference and exacerbates fall risk in older adults with mild cognitive impairment (MCI). Previous studies have demonstrated that Tai Chi (TC) may improve cognitive function and dual-task gait performance. Intriguingly, with emerging studies also indicating the potential of transcranial direct current stimulation (tDCS) in enhancing such motor-cognitive performance, whether combining tDCS with TC might be superior to TC alone is still unclear. The purpose of this study was to investigate the effects of combining tDCS with TC on dual-task gait in patients with MCI.Materials and Methods: Twenty patients with MCI were randomly assigned to receive either anodal or sham tDCS, both combined with TC, for 36 sessions over 12 weeks. Subjects received 40 min of TC training in each session. During the first 20 min, they simultaneously received either anodal or sham tDCS over the left dorsolateral prefrontal cortex. Outcome measures included dual-task gait performance and other cognitive functions.Results: There were significant interaction effects between groups on the cognitive dual task walking. Compared to sham, the anodal tDCS group demonstrated a greater improvement on cadence and dual task cost of speed.Conclusion: Combining tDCS with TC may offer additional benefits over TC alone in enhancing dual-task gait performance in patients with MCI.Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [TCTR20201201007].

Highlights

Engaging in a secondary task while walking increases motor-cognitive interference and exacerbates fall risk in older adults with mild cognitive impairment (MCI)
The anodal transcranial direct current stimulation (tDCS) group demonstrated a greater improvement on cadence and dual task cost of speed
Of the 21 participants, one patient in the a-tDCS+ Tai Chi (TC) group did not complete the study due to a low adherence to the protocol (4/36 sessions), the data of this participant was withdrawn from the analysis

Summary

Introduction

Engaging in a secondary task while walking increases motor-cognitive interference and exacerbates fall risk in older adults with mild cognitive impairment (MCI). Individuals with cognitive impairment may be susceptible to dual-task interference because there are fewer attentional resources available for the simultaneous performance of secondary tasks (Nascimbeni et al, 2015). Decreased gait velocity and increased variability in stride time when shifting between a single task and a dual task have been previously reported in older adults with MCI (Muir et al, 2012). Due to a strong link between dual-task gait performance and cognitive impairment, dual-task interference or dual task cost (i.e., the difference between the scores of the dual-task and single-task performances) was shown to be predictive of future cognitive decline and greater risk of falls (De Cock et al, 2017)

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