Randomized, Triple-Blind, and Parallel-Controlled Trial of Transcranial Direct Current Stimulation for Cognitive Rehabilitation after Stroke

Right hemisphere stroke frequently results in hemispatial neglect, a disabling condition that can significantly impede the recovery process. The chronic presence of neglect has been linked to poorer outcomes in both cognitive and motor domains. As an adjunct to conventional neuropsychological interventions, transcranial direct current stimulation (tDCS)-a noninvasive technique that modulates neural excitability through low-intensity electrical currents-has gained attention for its potential to enhance cortical plasticity and support functional improvement in affected individuals. In this study, we propose a combined intervention protocol aimed at reducing symptoms of post-stroke hemispatial neglect. It consists of a cathodal tDCS protocol combined with a computerized neuropsychological rehabilitation program specifically designed for the rehabilitation of hemispatial neglect. The neuromodulation strategy is to reduce the hyperactivation of the undamaged hemisphere based on the interhemispheric rivalry model. The intervention consists of 2 weeks, 10 sessions (from Monday to Friday), 45 min each, of tDCS and conventional cognitive stimulation concurrently applied. The tDCS is applied by an 8-channel high definitiontDCS (HD- tDCS) device for 20 min and at 2 mA of intensity. The cathode is positioned over the left posterior parietal cortex (P3 following 10/20 system for electroencephalogram [EEG] electrode placement), and return electrodes are placed at C3, CP5, CP1, Pz, PO3, PO7, and P7. A neuropsychological and functional assessment was carried out at baseline and after the end of the intervention. The primary aim of the present study is to describe the protocol for a parallel, randomized, triple-blind experimental design. To ensure the feasibility of the protocol and its potential efficacy, a comprehensive description of the procedures applied to a single pilot participant is provided. Incorporating tDCS neuromodulation strategies into cognitive rehabilitation processes may lead to shortened intervention times and improve the functional status and quality of life of patients.