Aging can cause degenerative changes in motor and cognition-related brain areas, presumably by interfering with gait performance in healthy aging populations. We aimed to assess the effects of transcranial direct current stimulation (tDCS) on single- and dual-task walking performances in healthy older adults using meta-analytic approaches.

Eleven studies were qualified based on the inclusion criteria: (a) healthy older adults, (b) treatment = tDCS protocols, (c) control = sham stimulation, (d) gait performance outcomes, and (e) randomized controlled trials using parallel or crossover designs. Effect sizes were estimated using standardized mean difference (SMD) to examine gait performances between active tDCS and sham stimulation. A separate random-effect meta-analysis was performed to determine the effects of tDCS protocols on gait performance during single- and dual-task walking tasks.

During single-task walking, the random-effects meta-analysis showed improvements in stride time variability (SMD = 0.203; p = 0.005) and functional mobility (SMD = 0.595; p < 0.001). Moreover, single-task walking performances were improved when the tDCS protocols targeted the primary motor cortex (SMD = 0.424; p = 0.005) and used off-line stimulation (SMD = 0.168; p = 0.008). During dual-task walking, tDCS improved gait speed (SMD = 0.177; p = 0.025) and dual-task cost for gait speed (SMD = 0.548; p < 0.001). Dual-task walking performances were advanced when the tDCS protocols targeted the dorsolateral prefrontal cortex (SMD = 0.231; p = 0.029) and multiple areas including prefrontal cortex (SMD = 0.382; p = 0.001), and applied off-line stimulation (SMD = 0.249; p < 0.001).

These findings indicate that the tDCS protocols may be a promising tool to support mobility and reduce gait-related challenges in the healthy aging population.