TDCS in Pediatric and Teenage Patients With Major Depressive Disorder During COVID-19 Pandemic

Inclusion Criteria: * Major Depressive Disorder (MDD) diagnosed through the clinical interview based on the Affective Disorders and Schizophrenia Agenda for schoolchildren-current version and for life K- SADS-PL for its acronym in English, with a single or recurrent episode lasting ≥4 weeks. * The current depressive episode must have a duration of less than 5 years and be at least greater than 2 months in which the patient meets the operational definition of MDD from the DSM-V. * CID scale with values equal to 17 or higher in the clinical evaluation. * No use of another medication during the intervention days. * They should not be taking antidepressants at the beginning of the study (last 4 weeks) or it must have passed the adequate time of "washing"/ clearance of antidepressant drugs established as 5 or more biological half-lifes or 5 days before the randomization. * To be able and willing to give their informed consent, both, the parent or tutor and the participant who is between the ages of 14-17 years. In the age group of 10-13 years the assent of the patient and the consent of the parent or tutor. * Use of benzodiazepines (eg lorazepam) equivalent to 20 mg of diazepam and which remains stable during the study. * Patients with an unchanged drug treatment for MDD in the last 4 weeks and who agree to switch the fluoxetine at the time of randomization, meeting the previously described antidepressant criteria. Exclusion Criteria: * Previous skull surgery. * Recent skull injury (6 months). * Use of central nervous system stimulants. * Respiratory System infections. * Does NOT sign or is unable to sign informed consent or legal tutors/parents do not consent. * Clinical condition or anomaly, which in the researcher's opinion, compromises patient´s safety or data quality. * Uncontrolled co-existent medical condition, progressive cerebral disorder, severe systemic diseases, symptomatic disease, cardiac disease, skin chronic diseases or damaged scalp which could interfere with tDCS stimulation. * Any skull metal implant (excluding dental filling or titanium plates) or medical devices (cardiac pacemaker, deep cerebral stimulator, drug infusion pump, cochlear implant, vagus nerve stimulator). * Direct researcher relatives or personnel directly involved in the study. * Acute suicide risk measured through the Montgomery Asberg depression rating scale (MADRS) \>4 points or positivity of the 4th or 5th item of The Columbia Suicide Severity Rating Scale (C-SSRS). * Depression resistant to treatment with \>4 well indicated drugs during the current episode. * Bipolar disorder history or current mania symptoms. * Treatment with electroshock therapy concomitantly and during the last 12 months. * Other relevant psychiatric disorders according to the DSM 5 (except generalized anxiety disorder, specific phobia or separation anxiety disorder). * Previous treatment with tDCS for a different disease to the major depressive disorder. * Intellectual development disorder previously documented or clinical evaluation fulfilling the CIE-F79 criteria. * Due to the fact that treatment with tDCS has counter-indications, will be excluded: those with history of non provoked seizures, convulsive disorders, history of febrile seizure, family history of epilepsy or brain tumor, pregnancy. * Counter-indication or history of adverse reactions from mild to severe to fluoxetine. Elimination criteria: * Patients that do not complete the neuropsychological assessment tests. * Interruption of the intervention of less than 50% of what was scheduled. * Onset of active suicidal ideation. * Active psychosis. * Start of emerging mania treatment. * Pregnancy.