Laughing gas might ease symptoms of depression, study finds

The dentist's office might be the last place you'd look to find a quick cure for an implacable bout of depression.

New research, however, suggests that laughing gas - the mixture of nitrous oxide and oxygen that eases the pain and anxiety of having dental work - may help ease treatment-resistant depression in about the time it takes to fill a cavity.

Interest in laughing gas as an antidepressant began with another sedative-turned-party-drug - ketamine.

The anesthetic ketamine induces a euphoric "out-of-body" high. When administered to the suicidally depressed, it is thought to be a promising "rescue" drug that offers quick relief, filling the four-to-six-week gap needed for many standard antidepressant medications to take full effect.

Like ketamine, nitrous oxide is an antagonist of the brain's NMDA receptor, a key bit of the cerebral machinery. Psychiatrists and anesthesiologists at Washington University in St. Louis, Missouri in the United States wondered whether nitrous oxide - a far less addictive drug than ketamine and one that may have fewer unforeseen side effects - might have the same benefits.

In a small pilot study published in the journal , researchers compared the effects of an hour of inhaled nitrous oxide on 20 patients whose depression had failed to yield to the standard antidepressants.