Could inhaling nitrous oxide treat major depression?

Inhaled nitrous oxide can effectively treat severe treatment-resistant major depression for up to two weeks, reports a phase 2 trial.
The crossover study included 24 patients with sustained and refractory depressive illness who were treated in random order with a single one-hour inhalation of either 25% or 50% of nitrous oxide or placebo (air/oxygen).
Treatments were separated by at least four weeks.
Participants had an average of 17.5 lifetime years of major depressive disorder and had failed a median of 4.5 adequate-dose/duration antidepressant drug treatments.