Effects of Transcranial Electrical Stimulation by Continuous Current on the Right and Left Dorsolateral Prefrontal Cortex Associated or Not with Non-invasive Vagus Nerve Stimulation in Adult Individuals with Chronic Stress

Stress is a disorder that significantly impacts the lives of affected individuals. Pharmacological treatment has limitations, justifying the search for non-pharmacological interventions. tDCS is a technique that modulates neuronal excitability and has shown promising results in various disorders.

Psychological stress affects a wide range of brain functions and poses risks for many mental disorders. However, effective therapies to alleviate or reverse its deleterious effects are lacking. Given that the pathophysiology of stress involves brain regions such as the prefrontal cortex, central amygdaloid nucleus, amygdala, medial amygdaloid nucleus, and ventral hippocampus, thus making the condition complex, there is a need for studies evaluating the effects of this intervention. We aim to contribute to the understanding of the role of tDCS and tVNS in managing stress.

Before participating in this research, volunteers will receive all information related to the study's objectives and methodological procedures. After agreeing to participate, they will sign the Informed Consent Form.

Study Location Patients will be selected following an evaluation based on inclusion and exclusion criteria and referred to the Clinic School of the Federal University of Alfenas (MG/Brazil), at the Laboratory of Neuroscience, Neuromodulation, and Pain Study (LANNED), located in the city of Alfenas, Minas Gerais, and at the Neuromodulation and Pain Unit (UNP) by the Egas Moniz Center for Interdisciplinary Research (CiiEM) of the Egas Moniz School of Health and Science, in the municipality of Almada, Setúbal - Portugal.

The design of the double-blind randomized clinical trial will be conducted, ensuring that participants are randomly assigned to experimental and sham groups and that the researcher applying the technique and the participants will not be aware of the allocation. The protocol will consist of 5 consecutive sessions of 20 minutes each. Data related to the anamnesis, ISSL, PSS-10, and PSQI will be evaluated at five different time points (Figure 1): before the intervention (T0), immediately after the end of the intervention (T1), and four weeks (T2) after the intervention ends (follow-up), following the CONSORT/2010 recommendations.