Investigating Transcranial Direct Current Stimulation as a Therapeutic Intervention for Conduction Aphasia: A Double-blind Controlled Study

A BSTRACT Aim and Background: Aphasia is a language disorder that develops as a result of cerebrovascular and neurodegenerative events, with conduction aphasia being a subtype characterized by speech errors and difficulties in object naming and word repetition. Transcranial direct current stimulation (tDCS) has emerged as a valuable neuromodulation technique employed both in clinical settings for therapeutic interventions and in neuroscience research to investigate brain function and neuroplasticity. This study investigated tDCS as a therapeutic intervention, aiming to increase synaptic plasticity of perilesional cortical regions by modulating neural excitation. Materials and Methods: Using a double-blind, controlled design, 20 patients were randomly allocated to receive either active anodal or sham stimulation for 5 consecutive days. Assessments were conducted prestimulation, poststimulation, and at 1-month follow-up. The study hypothesized that anodal stimulation would reduce paraphasias while improving object naming and repetition abilities. Results: The findings showed that the active group’s paraphasia scores during object naming tasks showed a significant reduction when compared with the sham group. For object naming ability, although between-group differences were not significant, the active group demonstrated significant within-group improvement from pre- to poststimulation ( P < 0.05, Cohen’s d = 0.54), demonstrating a moderate magnitude of effect with potential clinical relevance. No significant differences were observed in repetition abilities. Conclusion: These findings suggest that tDCS positively impacts language disabilities in conduction aphasia, particularly for paraphasia and object naming tasks. The moderate effect size in object naming improvement warrants further investigation with larger sample sizes to establish whether tDCS is a viable therapeutic option for conduction aphasia rehabilitation programs.