Does Laughing Gas Improve Depression?

Because the anesthetic ketamine, an NMDA receptor antagonist, has acute antidepressant effects in major depression (NEJM JW Psychiatry Sep 26 2013), these investigators conducted a double-blind, placebo-controlled, crossover trial of another anesthetic and NMDA receptor antagonist, nitrous oxide (N₂O). One author has patent interests in using N₂O for depression.

The 20 participants (mean age, 48) had longstanding nonpsychotic major depressive disorder (mean, 19 years) and had failed a median of eight adequate antidepressant trials (including electroconvulsive therapy in 4 patients and vagus nerve stimulation in 3). Patients received 1-hour inhalation of 50% N₂O /50% oxygen or placebo (50% nitrogen/50% oxygen) 1 week apart and were randomized…