Abstract
Background: Impaired inhibitory control and other impulsive behaviors are common after traumatic brain injury (TBI), but directly targeted treatments remain limited. Objective: To evaluate the preliminary effects and tolerability of prefrontal transcranial direct current stimulation (tDCS) paired with executive function training in Veterans with a history of TBI and clinically relevant impulsive behavior. Methods: Twenty-five Veterans with mild (n=18), moderate (n=4), or severe (n=3) TBI were randomized in a double-blind design to active (n=13) or sham (n=12) tDCS. Participants completed five daily sessions of 2 mA tDCS for 20 minutes (anode AF7, cathode AF8) delivered during approximately 46 minutes of BrainHQ cognitive training. An untrained response inhibition task with simultaneous response and stop cues was administered before and immediately after the intervention and at 1-, 2-, and 3-month follow-ups. The primary outcome was the percentage of commission errors on stop trials. Results: The active group showed a greater pre- to post-intervention reduction in stop trial commission errors than the sham group (Group x Time: beta = -0.011, SE = 0.004, p = .004). No significant change was detected from post-intervention through the follow-up period, suggesting this level of reduced errors persisted for three months post-intervention. Self-reported impulsivity and performance on the cognitive training tasks did not show differential improvement after correction for multiple comparisons. Adverse effect ratings were low and did not differ between groups. Conclusions: Five sessions of prefrontal tDCS paired with cognitive training were well-tolerated and produced preliminary evidence of improved response inhibition on an untrained task. These results, while requiring confirmation in a fully powered trial, suggest that this neuroplasticity-based intervention may be a promising non-pharmacological approach for patients who suffer a TBI and are affected by impulsivity.