Laughing gas could treat depression

Most people who have suffered from clinical depression will say they wish there were an instant cure. The creation of a pill like that is probably years away at best, but now a team of scientists think they've found a promising alternative: laughing gas.

Researchers at Washington University in St. Louis say they've discovered that nitrous oxide -- a somewhat mild general anesthetic often used as a sedative in dental surgery -- may be an effective, rapid treatment for severe depression when a patient isn't helped by standard therapies such as antidepressant medications.

The findings from this small pilot study of 20 patients were published Tuesday in the journal Biological Psychiatry.

For the study, the researchers gave patients two rounds of treatments, some with placebos and some with a combination of half oxygen and half nitrous oxide, which is what dentists give to patients undergoing dental procedures.

The researchers found two-thirds of the patients who received the gas reported significant improvements in their depressive symptoms, compared to only a third of patients in the placebo group.

"The nitrous oxide treatment improved it above and beyond the placebo," Dr. Peter Nagele, assistant professor of anesthesiology at Washington University's School of Medicine, said in a podcast produced by the school. "This was fairly rapid, so at two hours. But our primary endpoint when we measured everybody -- we asked the patients to come back the next day -- was sustained to a day. "

He said some patients in the study experienced complete remission from their depression symptoms, though their findings would need to be replicated with other studies since the researchers only followed up with patients twice within a 24-hour period of administering the gas.

Nagele was prompted to conduct his study on laughing gas after reviewing positive findings from a similar study on ketamine as a treatment for depression. Ketamine is another much more powerful type of anesthesia that's given to surgery patients to ensure they do not wake up during a procedure.

"Interestingly, katamine and nitrous oxide, or laughing gas, share several aspects of how they work in the brain, and one core affect site is called the NMDA receptor," said Nagele. "Both nitrous oxide and ketamine act on this mechanism."

A 2013 study led by researchers at Mount Sinai Medical Center in New York that involved 72 patients with treatment-resistant depression, found almost 64 percent of patients showed improvements in symptoms within a day, and 46 percent had improved symptoms one week later.

NMDA glutamate receptors are neurotransmitters that are involved in memory and cognitive function. Though research on the topic is still limited, some pharmaceutical companies are exploring the idea of developing drugs that work in the same way.

However, laughing gas, which is inhaled would be easier to administer to patients than an intravenous dose of ketamine. Laughing gas has also been found to have fewer side effects.