Effect Of Network-based Transcranial Direct Current Stimulation On Gait And Working Memory In Older Adults

Gait is regulated by high-level cognitive function and motor control, mostly involving interactions between large-scale brain networks, such as dorsal attention network (DAN) and default network (DN). Our prior study demonstrated that a novel transcranial direct current stimulation (tDCS) paradigm designed to simultaneously facilitate excitability of DAN and suppress excitability of DN (DAN + /DN-tDCS) may modulate gait characteristics in young healthy adults. However, these results warrant additional research on this type of network-based tDCS for the older populations. PURPOSE: To investigate the effects of DAN + /DN-tDCS on gait and working memory in healthy older adults. METHODS: In this cross-over double-blind study, 28 healthy elderly aged 68.5 ± 4.65 years were recruited and randomized to receive tDCS or Sham stimulation. Immediately before and after stimulation, participants completed N-back (0-back and 1-back) tasks and gait assessment under two conditions: walking at self-selected speed and walking while counting backward (i.e., dual-task walking). Outcomes included the stride length, stride time, step width, step velocity in both single and dual-task walking, as well as the accuracy and reaction time (RT) in the N-back task. RESULTS: Two-way ANOVA showed significant interaction effects in step velocity in both single (F = 4.027, p = 0.050) and dual-task (F = 4.601, p = 0.036) walking. Post-hoc tests results indicated that only participants who received tDCS showed improvement in step velocity in both single (p = 0.022) and dual-task walking (p < 0.001) compared to pre-intervention, with increases of 3.840 cm/s and 5.255 cm/s, respectively. Moreover, a significant interaction effect was found in accuracy (F = 6.296, p = 0.015) and RT (F = 6.731, p = 0.012) in the 1-back task. Post-hoc analysis showed that only participants who received tDCS showed improvement in accuracy (p < 0.001) and RT (p < 0.001). Additionally, change of RT in 1-back task was negatively associated with step velocity (r = -0.542, p = 0.003 ) in single task in older adults who received tDCS. CONCLUSIONS: DAN + /DN-tDCS could improve the gait performance under simple or complex situations and enhance working memory under high cognitive load in older adults. The National Natural Science Foundation of China (11932013; 12302418)