The effect of a single session of tDCS on attention in pediatric acquired brain injury: Characterising inter-individual structural and functional network response variability

Background Approximately 1 in 4 children who sustain an acquired brain injury (ABI) have attention difficulties impacting education, employment, and community participation. These difficulties arise from dysfunction in attention-related brain networks, incentivising the use of transcranial direct current stimulation (tDCS). Objective/Hypothesis We investigated whether a single tDCS session improved attention following childhood ABI and whether baseline structural connectivity (sc), functional connectivity (fc), attention, and/or simulated electric fields (E-field) explained variability in response. Methods In a randomised, single-blind, within-subject, sham-controlled trial, 15 children with ABI (mean 12.7 years) and 15 healthy controls (HCs) received three single tDCS sessions (1mA dorsolateral prefrontal cortex [dlPFC], 1mA inferior frontal gyrus [IFG], sham; 20min) during gamified attention training. We examined post-intervention changes in attention according to flanker and stop signal reaction time (RT). We used multi-modal analyses (high-density electroencephalography [HD-EEG], diffusion tensor imaging, magnetic resonance imaging) to investigate inter-individual variability in tDCS response, according to associations between RT change and baseline fc, sc, attention, and E-fields. Results Although no effect of active versus sham tDCS was found overall, participants with lower theta or higher gamma default mode network connectivity and poorer attention at baseline showed greater response to tDCS. Higher E-fields were associated with greater response. No serious adverse effects occurred. Conclusions A s ingle tDCS session targeting dlPFC or IFG did not improve attention following pediatric ABI. We demonstrated how HD-EEG source-based connectivity may be used to personalise tDCS. Future research should explore whether personalization, and/or repeated tDCS sessions can improve attention following pediatric ABI.