Home-based tDCS in Major Depressive Disorder

Patients meeting one of the following criteria may be eligible to participate in this study. 1. Patients with medication-resistant MDD who have undergone rTMS or ECT and responded to it but whose benefit has lapsed, and they need repeat a rTMS or ECT course that they cannot access 2. Patients with medication-resistant MDD who have undergone rTMS or ECT and responded to it but whose benefit has lapsed, and they need repeat a rTMS or ECT course that they cannot access 3. Patients with medication-resistant MDD who are undergoing rTMS or ECT and responding, but cannot continue to get the rTMS or ECT course due to COVID-19 pandemic-related regulations or other access concerns 4. Patients with medication-resistant MDD who are referred to rTMS or ECT and are found well qualified but cannot access rTMS or ECT due to COVID-19 pandemic-related regulations or other access concerns. The benefits of this project address a present need due to the COVID-19 pandemic, but also go beyond the present situation and address a larger, pre-existing need. Across all these potential groups of participants, prospective participants will: * need to have a primary psychiatrist who agrees to their participation in the study and is willing to continue to follow the patient and work collaboratively with the study team * need to be assessed by their primary psychiatrist to be stable enough to be able to remain at home and participate in the present study without undue risk to their safety * need to be living with an adult willing and capable to provide oversight and learn to deliver the home-based tDCS * have the capability to connect with the study team for daily supervision of the intervention sessions and close safety monitoring, and be willing to commit to doing so Inclusion Criteria: Individuals with MDD Participants will be men and women who: * Are aged 50 or older * Able to read, write, and communicate in English * Have a caregiver who is willing and able to provide the home tDCS sessions. * Participants must be under the care of a treating psychiatrist who approves of the study participation and believes that TMS or ECT is indicated for his/her patient but that * it would not endanger the patient to participate in the present study rather than pursue such alternative, or * the patient could not gain access to TMS or ECT due to COVID-19 (The depression phase of bi-polar disorder is not a reason for exclusion if the treating psychiatrist believes TMS or ECT would be indicated). Participants with MDD must fit into one of the following 3 groups (medication-resistant MDD defined as 1) participant's condition has not responded to prescribed antidepressant medication; 2) participant is medication intolerant, or 3) some other underlying reason): * Patients with medication-resistant Major depressive disorder (MDD) who have undergone repetitive transcranial magnetic stimulation (rTMS) or electroconvulsive therapy (ECT) and responded to it but whose benefit has lapsed and they need repeat rTMS or ECT course that they cannot access; * Patients with medication-resistant MDD who are undergoing rTMS or ECT and responding, but cannot continue to get the rTMS or ECT course due to COVID-19 pandemic-related regulations or other access concerns * Patients with medication-resistant MDD who are referred to rTMS or ECT and are found well qualified but cannot access rTMS or ECT due to COVID-19 pandemic-related regulations or other access concerns. Further, participants must: * Meet criteria for a diagnosis of MDD according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) (American Psychiatric Association, 2000), as determined via an tele-health interview with a study psychiatrist, and confirmed with the Mini International Neuropsychiatric Interview (MINI; Version 5.0.0) (Sheehan et al., 1998) and the prospective participant's primary psychiatrist. * Currently experiencing a major depressive episode of at least four weeks' duration as part of a unipolar or bipolar depression. Score will need to be at least 20 on the MADRS. Further, participants must have a willing and eligible caregiver-administrators who is: * At least 21 years of age * Able to read, write, and communicate in English * Self-reported computer proficiency and willingness to learn how to use tDCS as defined by "yes" answers to the questions "Do you feel comfortable using a computer?" and "are you willing to learn * How to administer tDCS?" Stated availability throughout the study period to administer tDCS sessions to the participant with MDD. Exclusion Criteria: * Exclusion criteria for participants with MDD will be: * Any DSM-psychotic disorder * Drug or alcohol abuse or dependence in the preceding three months; * Concurrent benzodiazepine medication; * High suicide risk (Utilizing the Beck Depression Inventory and the Hamilton Depression Scale, suicide risk will be assessed at baseline by the study psychiatrist) ; * History of clinically defined neurological disorder or insult; Metal in the cranium or skull defects; * Skin lesions on the scalp at the proposed electrode sites; * Pregnancy. * Medical devices (i.e. cardiac pacemaker, deep brain stimulator, medication infusion pump, cochlear implant, vagus nerve stimulator). * Previous skull surgery with resultant skull defects * Inability to understand study procedures following review of the Informed Consent form. Understanding will be assessed by asking the participant with MDD to answer the following three questions: 1. What is the purpose of this study? 2. What are the risks of study involvement? 3. If you decide to participate, are you allowed to withdraw from the study at any time? Answers will be recorded by study personnel on the "Assessment of Protocol Understanding" form. Insufficient understanding will be defined by one or more incorrect answers, as determined at the discretion of the investigator. Exclusion criteria for Participant caregiver-administrators: * Poor eyesight, * Severe arthritis in the hands, pain, deformity or other condition that interferes with successful administration of tDCS. * Inability to understand study procedures following review of the Informed Consent form. Understanding will be assessed by asking the participant caregiver-administrator to answer the following three questions: 1. What is the purpose of this study? 2. What are the risks of study involvement? 3. If you decide to participate, are you allowed to withdraw from the study at any time? Answers will be recorded by study personnel on the "Assessment of Protocol Understanding" form (see attached). Insufficient understanding will be defined by one or more incorrect answers, as determined at the discretion of the investigator.