B - 36 Investigating High-Definition Transcranial Direct Current Stimulation for Remediating Word Finding Difficulty in Civilians with a History of Chronic Traumatic Brain Injury: a Pilot Study

Abstract Objective Verbal-retrieval deficits often occur after traumatic brain injury (TBI), but no effective treatment is available. In this study, High-Definition Transcranial Direct Current Stimulation (HD-tDCS) was applied to examine its potential effects on cognitive, especially verbal-retrieval, performance in individuals with chronic TBI. Method Four adults (mean age 48 years; 3 females) with self-reported word-finding difficulty confirmed by objective measures following mild to moderate non-military TBIs sustained over a year ago underwent a double-blind, cross-over, randomized, sham-controlled trial. Each participant received 10 sessions of active HD-tDCS and sham stimulation over the superior medial frontal cortex. A battery of neuropsychological tests was administered including verbal-retrieval measures (i. e. letter fluency, category fluency, Boston Naming Test/BNT) at baseline, immediately, and 8 weeks post-treatment. Post-treatment performance was compared to baseline using 2-tailed paired t-tests. Results Improvements on letter fluency were observed between baseline and immediate assessments post active HD-tDCS, approaching statistical significance (p = 0.076, Cohen’s d = 0.957, 7.5 ± 5.7 more items). No immediate effects with sham HD-tDCS (p > 0.10, 1.5 ± 3.5 more items) and no sustained effects (8 weeks after) were found with either active or sham HD-tDCS (ps > 0.10). Additionally, no significant changes were observed for category fluency or BNT (all ps > 0.10). Conclusion While our pilot study suggests a potential benefit for improved letter fluency immediately following active HD-tDCS compared to sham, the lack of sustained improvement after 8 weeks and the observed variability across different tests acknowledges the need for future larger-scale investigation across multiple cognitive domains.