Association of Transcranial Direct Current Stimulation and Neurofeedback With Declarative Memory and Cerebral Arterial Flow in University Students: Protocol for a Double-blind Randomized Controlled Study

Grecco, Leandro H; Gonçalves, Giuliano R; Perri, Bárbara Neiva; Bispo, Breno Alexander; Grandin, Isabella Favilla Jorge; Gomes, Paula Valentina Nunes Dias; Bocchi, André Alexandre; Oliveira, Kennedy Martinez; Maldonado, Diogo Correa; da Silva, Marcelo Cavenaghi Pereira · 2022 · DOAJ

DOI: 10.2196/36294

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Summary

This paper presents the protocol for a prospective, double-blind, randomized controlled trial designed to evaluate the combined effects of transcranial direct current stimulation (tDCS) and neurofeedback on declarative memory and cerebral blood flow in healthy university students. The study is motivated by the need for specific, controllable methods to enhance cognitive performance, as traditional factors like motivation and attention are difficult to standardize. While tDCS and neurofeedback have individually shown promise in modulating brain activity and improving working memory, no prior studies have investigated their combined efficacy. The authors hypothesize that applying anodic tDCS to the dorsolateral prefrontal cortex (DLPFC) alongside neurofeedback training will significantly improve declarative memory responses and increase cerebral arterial flow compared to placebo. The study will recruit 60 undergraduate students (aged 18–30) from medicine and dentistry programs, with 30 assigned to an active tDCS plus neurofeedback group and 30 to a placebo tDCS plus neurofeedback group. Participants will undergo ten 20-minute sessions over two weeks. The active group will receive 2.0 mA anodic stimulation at the left DLPFC (F3) and cathodic stimulation at the contralateral supraorbital area, while the placebo group will receive sham stimulation where the current turns off after 20 seconds. Both groups will engage in neurofeedback training using the NeuroSky ThinkGear EEG device and TuSion software, which visualizes attention levels to facilitate self-regulation. Primary outcomes include performance on the Stroop test (measuring reading fluency and color-naming interference) and secondary outcomes include cerebral blood flow velocities in the middle cerebral artery, measured via transcranial Doppler ultrasound. Data will be analyzed using t-tests or nonparametric equivalents, with significance set at P < .05. The protocol outlines a rigorous blinding procedure where only one collaborator knows the allocation, ensuring that evaluators and participants remain blinded to the stimulation condition. Exclusion criteria include psychiatric disorders, neurological trauma, epilepsy, recent drug abuse, use of central nervous system medications, metallic head implants, and pregnancy. The study is registered in the Brazilian Clinical Trials Registry (RBR-7zs8b5) and approved by the local ethics committee. Enrollment began in July 2022, with statistical analysis of secondary outcomes currently underway. This research is significant because it addresses a gap in the literature regarding the synergistic potential of noninvasive neuromodulation techniques. By combining tDCS, which induces plasticity-related changes in neural circuits, with neurofeedback, which trains self-regulation of brain activity, the study aims to provide preliminary evidence on whether this dual approach can more effectively enhance memory consolidation and cerebral hemodynamics than either method alone. The findings could inform the development of low-cost, accessible cognitive enhancement tools for educational and clinical settings, offering a safe alternative to pharmacological interventions for cognitive decline or learning difficulties.

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• neuro workload indices