Xenon Inhalation Therapy for Major Depressive Disorder and Bipolar Disorder

Eligibility Criteria

• * Patient who meets DSM-V Criteria for MDD or Bipolar Depression (according to DSM-V), as the primary focus of treatment.
• * Able to understand the risks and benefits of participating in this clinical trial and give informed consent, per judgment of the investigator.
• * Age greater than or equal to 18 years but less than or equal to 65 years.
• * Montgomery Asberg Depression Rating Scale ≥20.
• * On an adequate antidepressant regimen (MDD) or on a mood stabilizing regimen (BP) that is stable for at least four weeks prior to enrollment.
• * Has reliable adult transportation from and to home.
• * Has a treating psychiatrist who is in agreement with the patient's participation in the study, and aware of the safety plan in the protocol.
• * No medical contraindications to receiving a xenon- or a nitrogen-oxygen mixture.
• * No serious or active pulmonary disease.
• * MDD or BP disorder with psychosis, schizophrenia, OCD, or a primary anxiety disorder.
• * Currently taking a benzodiazepine (including PRN).
• * Unwilling or unable to comply with study procedures.
• * Active substance abuse in the past 60 days, diagnosis of substance dependence in the past 12 months, currently active smokers of any substance, including prescription marijuana.
• * Pregnant women or women of child bearing potential who are not using a medically accepted means of contraception.
• * Any unstable medical illness (cardiovascular, hepatic, renal, respiratory, endocrine, neurological, or hematological disease or uncontrolled seizure disorder).
• * Any history of brain injury and any active state involving entrapped air/gas within a body cavity with the potential to expand causing organ distension/compression (e.g., bowel obstruction, pneumothorax, or pneumocephalus).
• * History of hypersensitivity to xenon; history of multiple adverse drug reactions.
• * Have taken any investigational psychotropic drug within the last 6 months.
• * Inability to agree to comply with the visit schedule or study procedures.
• * Not appropriate for participation in a research trial per judgment of the investigator.