Transcranial direct current stimulation of the dorsolateral prefrontal cortex improves dual-task performance in people with stroke

Gait and cognitive dysfunction in people with stroke are often exacerbated during dual tasks, limiting their ability to perform daily tasks. This study aimed to investigate the effects of anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) on dual-task performance in individuals with chronic stroke. Unlike previous studies that primarily targeted motor cortical regions (e.g., M1), our innovative approach focuses on stimulating the DLPFC, a key cognitive region, to enhance cognitive-motor resource allocation, reduce dual-task costs (DTCs), and ultimately improve both mobility and cognitive performance. In this sham-controlled, within-subject crossover study, 53 participants with chronic stroke underwent two randomized tDCS sessions (active and sham) over 1 week. Following 30 min of stimulation, a comprehensive assessment was conducted to evaluate both motor and cognitive DTCs, gait parameters, cognitive functions across various single- and dual-task conditions. Anodal tDCS over the left DLPFC significantly improved lower limb mobility, including gait speed (p < 0.001), stride length (p < 0.001), and foot strike angle (p < 0.001), compared to sham stimulation. Enhanced cognitive performance was observed during dual-task conditions, with significant improvements in Random Number (p = 0.001), Counting Forward (p < 0.001), and Serial Subtraction (p = 0.001) tasks. Notably, tDCS reduced DTCs by improving cognitive response rate during Serial Subtraction (p = 0.002). These effects were specific to dual-task conditions, as no significant changes were observed during single-task conditions. Anodal tDCS over the left DLPFC reduces DTCs by enhancing cognitive-motor integration, leading to significant improvements in both mobility and cognitive efficiency in individuals with chronic stroke. This novel approach highlights the DLPFC as a promising therapeutic target for addressing dual-task impairments in stroke rehabilitation. Trial registration: This trial was registered at ClinicalTrials.gov (NCT06818240).