Major Depressive Disorder (MDD) is a common mental disorder, with a lifetime prevalence of 15% and an incidence of 5% per year. Its core symptoms include lack of pleasure in daily activities, thoughts of guilt and depressed mood. According to the World Health Organization, MDD is one of the ten most impairing conditions, leading to missing workdays, loss of quality of life and increasing expenses in health care. Besides, about 1% of patients with MDD complete suicide. Moreover, one third of patients with MDD remain depressed after more than two adequate treatments, i.e., they are refractory to conventional antidepressant treatments; also, most treated patients remain with residual symptoms. Therefore, the development of new treatments is necessary. Transcranial direct current stimulation (tDCS) is a novel, promising technique in the study of several neuropsychiatric conditions.

Transcranial DCS is a non-invasive brain stimulation method in which a low intensity direct current is applied through the skull, with neurophysiologic studies showing that a considerable amount of electrical current reach the brain tissues, vis-à-vis the specified parameters. Thus, the DC could be applied over brain MDD-related areas, such as the dorsolateral prefrontal cortex, thereby leading to neuroplasticity and MDD treatment. Indeed, some pilot studies showed that tDCS might ameliorate depressive symptoms. However, it is necessary to replicate these findings in larger populations to increase the generalizability of the results and to verify the efficacy of the intervention. Our aim is to perform a double blind, randomized, factorial study comparing tDCS and sertraline for MDD treatment, enrolling 120 eligible patients of both genders between 21-65 years not presenting active suicidal ideation. They will be allocated in 4 groups at random to receive active tDCS or sham and sertraline 50mg/day or placebo. Transcranial DCS will be applied in a daily basis for 10 consecutive working days (2 weeks), after that, the patients will be followed weekly for 6 weeks. Our primary outcome is the depression rating scores at 6 weeks, measured by the Hamilton Depression Rating Scale (HDRS), 17-itens. In conclusion, our purpose is to perform a clinical tDCS study to verify its efficacy in the treatment of MDD in a sample of patients of several levels of severity and refractoriness.

Our secondary objectives are also to verify the safety of the intervention as well as to compare tDCMajor Depressive Disorder (MDD) is a common mental disorder, with a lifetime prevalence of 15% and an incidence of 5% per year. Its core symptoms include lack of pleasure in daily activities, thoughts of guilt and depressed mood. According to the World Health Organization, MDD is one of the ten most impairing conditions, leading to missing workdays, loss of quality of life and increasing expenses in health care. Besides, about 1% of patients with MDD complete suicide. Moreover, one third of patients with MDD remain depressed after more than two adequate treatments, i.e., they are refractory to conventional antidepressant treatments; also, most treated patients remain with residual symptoms. Therefore, the development of new treatments is necessary. Transcranial direct current stimulation (tDCS) is a novel, promising technique in the study of several neuropsychiatric conditions.

Transcranial DCS is a non-invasive brain stimulation method in which a low intensity direct current is applied through the skull, with neurophysiologic studies showing that a considerable amount of electrical current reach the brain tissues, vis-à-vis the specified parameters. Thus, the DC could be applied over brain MDD-related areas, such as the dorsolateral prefrontal cortex, thereby leading to neuroplasticity and MDD treatment. Indeed, some pilot studies showed that tDCS might ameliorate depressive symptoms. However, it is necessary to replicate these findings in larger populations to increase the generalizability of the results and to verify the efficacy of the intervention. Our aim is to perform a double blind, randomized, factorial study comparing tDCS and sertraline for MDD treatment, enrolling 120 eligible patients of both genders between 21-65 years not presenting active suicidal ideation. They will be allocated in 4 groups at random to receive active tDCS or sham and sertraline 50mg/day or placebo. Transcranial DCS will be applied in a daily basis for 10 consecutive working days (2 weeks), after that, the patients will be followed weekly for 6 weeks. Our primary outcome is the depression rating scores at 6 weeks, measured by the Hamilton Depression Rating Scale (HDRS), 17-itens. In conclusion, our purpose is to perform a clinical tDCS study to verify its efficacy in the treatment of MDD in a sample of patients of several levels of severity and refractoriness.

Our secondary objectives are also to verify the safety of the intervention as well as to compare tDCS vs. sertraline and the association of sertraline and tDCS vs. each treatment alone in major depression treatment.