Network-based transcranial direct current stimulation may improve gait and cognitive function in older adults: a randomized controlled crossover study.

OBJECTIVE: Gait abnormalities and cognition decline are significant challenges in aging, impacting the independence of older adults. Recent studies suggest that the dorsal attention network (DAN) and default network (DN) in the brain play crucial roles in modulating gait patterns and cognitive function. This study aimed to investigate whether concurrent transcranial direct current stimulation (tDCS) targeting DAN and DN could synergistically improve gait parameters and cognition among healthy older adults. METHODS: In this cross-over double-blind study, 28 healthy elderly aged 68.500 ± 4.647 years were randomized to receive tDCS or Sham stimulation, with electrode placement and current intensity optimised using the Stimweaver® technique. Immediately before and after stimulation, participants completed gait assessment under two conditions: walking at self-selected speed (single-task walking) and walking while counting backward (i.e., dual-task walking), as well as N-back (0-back and 1-back) tasks. Outcome measures included stride length, stride time, step width, gait speed in both single and dual-task walking, as well as dual-task cost to gait. Cognitive function outcomes encompassed accuracy, reaction time, and inverse efficiency scores (IES) in the 0-back and 1-back tasks. RESULTS: Compared to Sham stimulation, tDCS led to significant improvements in gait speed under both single-task and dual-task conditions, with average increases of 0.038 m/s and 0.053 m/s, respectively. Additionally, 1-back reaction time decreased by 57 ms and IES by 0.131 following tDCS, with no significant changes under Sham stimulation. However, no change in dual-task cost was observed. Moreover, improvements in working memory were associated with changes in gait speed in single-task walking. Blinding efficacy was excellent, and participants’ subjective belief in the type of stimulation received did not influence the observed functional benefits of tDCS. CONCLUSION: In healthy older adults, a single session of tDCS designed to modulate DAN and DN excitability concurrently improved gait speed in both single and dual-task walking, as well as working memory. These preliminary findings suggest that gait and working memory may be modifiable through neuromodulation approaches involving DAN and DN. Further studies are warranted to explore the relationship between gait, working memory, and these two brain networks using neuroimaging means. TRIAL REGISTRATION: ChiCTR2300077186-11/01/2023.