Transcranial direct current stimulation alleviates cognitive impairment and neurological dysfunction after stroke: a functional near-infrared spectroscopy study

Cognitive impairment is common in stroke patients. Transcranial direct current stimulation (tDCS) is a promising tool for alleviating cognitive impairment and altering cerebral cortex excitability. In this study, we aimed to evaluate whether tDCS improves cognitive impairment after stroke by altering cortical activation. We recruited 30 post-stroke patients and 30 healthy individuals. We placed the anodes on the F3 and Fp2 electrodes with an intensity of 2 mA to observe changes in cortical activation during the N-back task in patients with cognitive impairment following stroke. Changes in cortical activation were observed with functional near-infrared spectroscopy during the N-back task in patients with cognitive impairment following stroke. Cognitive function was impaired after stroke; cortical activation in the left ventrolateral prefrontal cortex (VLPFC) during the N-back task decreased after stroke. Cognitive function and cortical activation in the left VLPFC during the N-back task increased after tDCSs in post-stroke patients, and reaction time changes during the N-back task were significantly correlated with changes in cortical activation in the left VLPFC and Montreal Cognitive Assessment after tDCSs. Cognitive impairment is common after a stroke, and deactivation of the left VLPFC can be used as a neural marker of cognitive impairment. tDCS is an effective technology that can improve cognitive function and cortical activation in patients with post-stroke cognitive impairment.