Nitrous oxide, known to many as laughing gas, is a promising treatment for severe depression, according to a study published in Science Translational Medicine.
Laughing gas can improve mood and relieve pain in the short term. It is one of the most widely used anesthetics and is also sold illegally. Previously, it was believed that its effect quickly passes.
Nitrous oxide blocks receptors in the brain N-methyl-D-aspartate. Why the effect on these receptors changes mood is still unknown. Ketamine, which is already approved in some countries to treat depression, acts on the same target. So the scientists decided to test whether laughing gas had the same sustained effect.
A 2014 study showed that nitrous oxide could relieve symptoms of depression for a day in people who do not respond to standard treatment for the disease. Then scientists did not check whether the effect lasts 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, the third — a placebo (a mixture of air and oxygen). For three months, participants received one inhalation per month. Scientists at the University of Washington and Chicago wanted to test how half the gas works because the full dose (50% nitrous oxide) can cause headaches, dizziness, and nausea.
In patients who received a half dose of laughing gas, two weeks after the course of treatment, symptoms of depression on the scale for diagnosing this disease were relieved by five points more than in the placebo group. Scientists estimate this as a significant effect.
The expressiveness of the effect of a half dose differed little from the effect of a 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 still cannot explain its mechanism.