Improved inhibitory control following combined transcranial direct current stimulation (tDCS) and cognitive training in individuals with traumatic brain injury and impulsivity

Impulsive behaviors, such as reduced inhibitory control, are common after traumatic brain injury (TBI). This study investigated the effectiveness of transcranial direct current stimulation (tDCS) over the prefrontal cortex paired with cognitive training to improve inhibitory control in Veterans with a history of TBI. This builds on our previous work showing a similar approach reduced impulsivity in a general clinically impulsive sample. Twenty-five Veterans with a history of mild (n=18), moderate (n=4), or severe (n=3) TBI and clinical history of impulsive behavior were randomized to receive either active (n=13) or sham (n=12) tDCS (2mA, 20 minutes, left anode/right cathode over prefrontal cortex) for 5 sessions. tDCS was delivered simultaneously with a battery of four computer-based cognitive training tasks. An untrained Stop Signal Task, a measure of inhibitory control, was administered at pre-intervention, post-intervention, and at 1-, 2-, and 3-month follow-ups. The primary outcome was the percentage of incorrect responses on stop trials (i.e. a failed inhibitory response). Using growth curve analysis, the active tDCS group showed a significant improvement in inhibitory control on the untrained Stop Signal Task immediately following the intervention, and these gains persisted for three months post-intervention. Combining prefrontal tDCS with cognitive training effectively improved inhibitory control in Veterans with TBI and clinically relevant impulsivity. This neuroplasticity-based intervention may be a promising non-pharmacological approach for patients who suffer a TBI and are affected by impulsivity.