The goal of this clinical trial is to investigate the impact of daily self-administered transcranial direct current stimulation (tDCS) therapy on the cognitive function of individuals with moderate to severe cognitive impairment resulting from a traumatic brain injury (TBI). The study aims to answer the following questions:

Does daily self-administered tDCS therapy, when combined with computerized cognitive training (CCT), improve cognitive function in TBI patients? Is CCT+tDCS with anodic stimulation more effective than CCT+tDCS with simulated stimulation in enhancing immediate and one-month post-treatment cognitive function? Does CCT+tDCS with anodic stimulation lead to better functionality immediately and one month after treatment compared to CCT+tDCS with simulated stimulation? Does CCT+tDCS with anodic stimulation have a positive impact on mood improvement immediately and one month after treatment compared to CCT+tDCS with simulated stimulation? Participants in the study will engage in CCT through a smartphone or tablet application and self-administer tDCS therapy for 20 minutes each day for a duration of one month. The tDCS therapy will involve applying a 2 mA anodic current to the prefrontal dorsolateral cortex (PFDL). Prior to the intervention, patients or their caregivers will receive training on the proper and safe usage of the tDCS device. Cognitive function, mood, and functionality will be evaluated before and after the intervention using appropriate measurement scales.

The outcomes of this clinical trial have the potential to identify an effective and accessible therapeutic approach to enhance cognitive function in individuals with moderate to severe TBI. The combination of tDCS therapy with CCT offers an appealing and feasible treatment strategy for these patients, particularly when conducted in a home setting. The findings from this study will guide future clinical trials in the field of cognitive rehabilitation for TBI patients. Researchers will compare active tDCS with sham tDCS to determine if there are differences in the primary outcomes mentioned.

Introduction: Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that can modulate neuronal excitability and enhance neuroplasticity. On the other hand, computerized cognitive training (CCT) therapy uses computers to improve cognitive domains through repeated practice of theoretically-driven skills and strategies. So far, the isolated use of tDCS and its combination with CCT have been explored in the cognitive recovery of patients with traumatic brain injury (TBI), yielding promising results. However, none of the studies to date have investigated the use of a self-administered therapy (by the patient and/or caregiver) that combines both interventions at home. The objective of this clinical trial is to evaluate the effect of daily self-administered tDCS therapy on cognitive function in patients with moderate-to-severe TBI-associated cognitive impairment.

Methodology: A prospective, controlled, double-blind, randomized clinical trial is proposed. The intervention will consist of (i) CCT delivered through a smartphone or tablet application and (ii) the application of 2 mA tDCS therapy (20 minutes of anodic current for the experimental group and 60 seconds for the control group) to the prefrontal dorsolateral cortex (PFDL) daily for one month, self-administered by the patient. Prior to the intervention, a training session will be conducted to instruct the patient (or caregiver) on the correct and safe use of the device. The primary outcomes will be cognitive function, mood, and functionality, measured before and after the intervention using appropriate scales.

Discussion: The results of this clinical trial could contribute to the identification of an effective and accessible therapeutic method to improve cognitive function in patients with moderate-to-severe TBI. The combination of tDCS therapy with CCT may offer an attractive and feasible therapeutic strategy for these patients, particularly when performed at home. The findings of this study may be useful in guiding future clinical trials in the field of cognitive rehabilitation in TBI patients.

Inclusion Criteria:

• Age between 18-65 years.
• Moderate to severe traumatic brain injury (TBI) according to classification 58 (see Table 3) with a duration of 6 to 12 months.
• Minimum of 8 years of education (completed basic education with literacy skills).
• Meeting diagnostic criteria (see Table 3) for mild or major cognitive impairment according to the Diagnostic and Statistical Manual of Mental Disorders (DSM).
• Capacity to make decisions and understand relevant information regarding participation in a clinical trial, assessed using the MacArthur Competence Assessment Tool for Clinical Research (MacCAT-CR) 60.
• Inclusion of patients with chronic TBI (defined for this study as more than 6 months of duration) based on the proposed mechanism of chronic TBI involving decreased cerebral neuroplasticity, leading to long-term cognitive dysfunction and functional limitations 62. Transcranial Direct Current Stimulation (tDCS) has shown effectiveness in enhancing neuroplasticity in various neurological and psychiatric conditions 63.

Exclusion Criteria:

• History of cognitive impairment unrelated to post-traumatic causes (for which the patient is being treated at Mutual de Seguridad).
• History of epileptic seizures.
• Pre-existing neuropsychiatric disorders.
• Presence of metallic objects in the body such as aneurysm implants, hemostatic clips, implanted electrodes, and electrical devices like pacemakers.

In this trial, masking will ensure blinding of interventions:

Participant: They will be unaware of receiving active tDCS therapy or sham intervention. A remote-controlled mobile app will facilitate this.

Investigator: They will be masked, not knowing the assigned interventions. This minimizes bias in data collection and analysis.

Outcomes Assessor: They will be masked to assigned interventions, ensuring objective and unbiased outcome assessment.

Implementing masking ensures that participants, care providers, investigators, and outcomes assessors remain unaware of the intervention received, maintaining trial integrity and validity.