[PUBLICATION] A Case of Sustained Antidepressant Effects and Large Changes in the Brain With a Single Brief Exposure to Nitrous Oxide

A Case of Sustained Antidepressant Effects and Large Changes in the Brain With a Single Brief Exposure to Nitrous Oxide

Nitrous oxide (N2O) has recently demonstrated antidepressant properties¹, but many aspects of this effect remain unclear, including the duration of exposure required for therapeutic effects and the profile of responders. We report the case of a 53-year-old woman with a history of recurrent depression and a current 2-year major depressive episode resistant to well-conducted escitalopram and venlafaxine therapy. She was included in the Protobrain study (NCT04199143 on clinicaltrials.gov), which consisted of exposing patients with treatment-resistant depression to 50% N20/50% O2 for 1 hour and investigating brain changes in response to the gas. The 50% N2O/50% O2 mixture was administered from a medical cylinder (Kalinox, Air Liquide, France) via a facial mask by a trained nurse under the supervision of a trained medical doctor (VG). Vital signs, N2O concentration and brain ultrasound were constantly monitored during the procedure, and gas flow was between 9 and 12 liters per minute. Within the first minutes of exposure, the patient quickly relaxed, although she experienced mild dissociative symptoms. After 10 minutes of exposure, she had nausea, and the procedure was stopped because she vomited. She agreed to resume the procedure, but ten minutes later, she vomited once more, and we decided to stop the procedure. She rapidly recovered from the side effects within a few minutes [Read more].