Safety and Feasibility of Combined Trigeminal and Occipital Transcutaneous Nerve Stimulation (CTO-TNS) in Major Depressive Disorder (MDD)

Inclusion Criteria: * The subject is capable of understanding the study and to sign an informed consent. * Subject is between the ages of 18 to 65 years old. * Unipolar major depressive disorder * Score on the Hamilton Depression Rating Scale (HDRS21) \> 22 * Current MDD episode \>3 months * Nonresponse with \>6 week use of one to six antidepressant in current episode Exclusion Criteria: * History of neurosurgical interventions. * Subjects with metal implants or shrapnel in their head, except for dental implants. * Skin lesion or inflammation at the region of the stimulating electrodes. * Pregnancy or Lactation. * Women of reproductive age not using efficient contraceptive method. * History of cerebrovascular event. * Psychotic or bipolar depression * History of schizophrenia, schizoaffective disorder or other non-mood disorder psychosis * Current delirium, dementia, amnestic disorder or other cognitive disorders * Clinically significant current suicidal intent as assessed by the investigator team. * Obsessive-compulsive disorder or post-traumatic stress disorder * Alcohol and non-alcohol psychoactive substance abuse or dependence * Significant cardiac, medical, or progressive neurological or medical illness * An implantable electrical device such as a pacemaker.