Nitrous oxide, known to many as laughing gas, is a promising drug against severe depression, confirmed a study published in Science Translational Medicine.
It has long been known that laughing gas can briefly improve mood and relieve pain. It is one of the most common anesthetics and is also sold illegally. Previously it was believed that its effect wore off quickly.
In the brain, nitrous oxide blocks receptors N-methyl-D-aspartate. Why influencing these receptors changes mood is still unknown. Ketamine, which is already approved in some countries for the treatment of depression, acts on the same target. Therefore, scientists decided to test whether laughing gas had the same lasting effect.
A 2014 study found that nitrous oxide could improve symptoms of depression for 24 hours in people who had not responded to standard treatment for the disease. At the time, scientists did not test whether the effect lasted longer.
The new study involved 24 people with treatment-resistant depression. The participants were divided into three groups. The first received a full dose of nitrous oxide, the second – half, and the third – a placebo (a mixture of air and oxygen). For three months, participants received one inhalation per month. Scientists from the University of Washington and the University of Chicago wanted to test how a half dose of the gas worked, because a full dose (50% nitrous oxide) can cause headaches, dizziness and nausea.
In patients who received half the dose of laughing gas, two weeks after the course of treatment, symptoms of depression on a scale for diagnosing this disease were relieved by five points more than in the placebo group. Scientists assess this as a significant effect.
The intensity of the effect of the half dose differed little from the effect of the full dose. At the same time, reducing the concentration of nitrous oxide significantly reduced the risk of side effects.
Scientists emphasize that, like ketamine, nitrous oxide gives a quick effect. However, they cannot yet explain its mechanism.