Laughing gas is used to relieve the pain of childbirth - but could it be the answer to depression, too? That's the suggestion behind a study testing the use of nitrous oxide - known as laughing gas - for low mood. Previous research has shown mixing the gas with oxygen can ease the symptoms of depression within hours or even minutes; antidepressants can take weeks. It's thought the gas blocks a brain chemical that could play a key role in the problem. Now this is being tested in a clinical trial.
The standard treatment for depression is antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs). These are said to work by increasing levels of the brain chemical serotonin, boosting mood. But they do not help everyone and some research has suggested that for mild to moderate depression they work no better than a placebo. Even when antidepressants do work, they can take weeks to have an effect. However, U.S. research suggests the brain chemical glutamate - involved in memory, learning and cognition - may be involved in depression.
Glutamate is a neurotransmitter - a chemical that passes messages from one nerve cell to another. It locks on to a receptor in the brain. Depression has been linked to glutamate's chronic overstimulation of this receptor (known as NMDA). Nitrous oxide - a weak anaesthetic used in dentistry and childbirth - is thought to block these receptors.
In a trial at Washington State University, patients will breathe in a mixture of nitrous oxide and oxygen, or a placebo, for one hour. The severity of their depression will be assessed 30 minutes and two hours after each treatment. Previous research has shown that drugs which block NMDA can have a powerful effect on symptoms of severe depression. A study of 22 patients given the drug ASD6765 intravenously showed 32 per cent had improvements within 80 minutes.
