Nitrous Oxide in Resistant Depression in Elderly Subjects: A Randomized, Double-blind, Comparator Trial

Prior treatment

• Contraindications to the use of MEOPA and any condition where air is trapped́ inside the body and its expansion could be dangerous: Pneumothorax, emphysema, intestinal obstruction, intracranial hypertension, known and unsubstituted vitamin B12 or B9 deficiency (based on a dosage less than 1 month old), Patients requiring oxygen ventilation; Any alteration in the state of consciousness, preventing patient cooperation; Head trauma; Gas embolism; Diving accident; Abdominal gas distension; Patient who has recently received an ophthalmic gas (SF6, C3F8, C2F6) used in eye surgery (as long as a gas bubble persists inside the eye and for at least 3 months)
• Person taking part in a clinical drug study or in a period of exclusion from any clinical study due to previous participation

Other illness

• Bipolar disorder, schizophrenic, neurodegenerative disease documented by MINI and MMSE (non-inclusion if MMSE< 24/30), addiction to one or more toxic substances
• Contraindications to MRI, including claustrophobia, a metallic foreign body in the eye, pacemaker, neurostimulator, cochlear implants (or non-removable electronic medical equipment), old-generation heart valves, vascular clips formerly implanted on a cranial aneurysm

Other

• Unstable somatic pathology (in particular unstable neurological or cardiological pathologies at risk of interfering with the diffusion of MEOPA) and any unexplained recent neurological abnormality
• Presence of active and significant psychotic symptoms, at the discretion of the investigator
• Legal incapacity and/or other circumstances rendering the patient incapable of understanding the nature, objective or consequences of the study

• Between 60 and 90 years old
• Diagnosis of depressive episode characterized according to DSM-5 criteria, confirmed by the Mini International Neuropsychiatric Interview (MINI)
• Depression score on the MADRS scale greater than 20 (Montgomery Asberg Depression Rating Scale)
• Patients resistant to at least one well-conducted antidepressant for the current depressive episode as assessed by the MGH-ATRQ scale
• Patients who can be subjected to the delivery of MOEPA via a facial mask
• A person who has signed an informed consent form
• Person affiliated with a social security or other regime