Laughing gas lifts low mood in 2 hours

LAUGHING gas can ease symptoms of depression in just two hours, new research suggests. A pilot study involving 20 patients who’d previously not responded to up to 12 different antidepressants found they were significantly more likely to improve with ‘laughing gas’ treatment than those given a placebo gas. The benefits lasted several days.

Now, in a new four-week study, 200 patients with depression will be treated with a mix of nitrous oxide (commonly known as laughing gas) and oxygen for an hour.

Up to one in four people with depression shows no improvement with standard therapies.

There is a major push to find alternatives. Some research has looked at a form of the party drug and anaesthetic ketamine. Nitrous oxide is being investigated as it works in a similar way to ketamine.

Whereas antidepressants typically work by increasing levels of the feel-good brain chemicals serotonin or dopamine, ketamine and nitrous oxide act on a different brain chemical, glutamate.

It is thought that depression may result in part from an excess of glutamate, which may disrupt how brain cells communicate with one another.

Ketamine can block the negative effects of glutamate, but one drawback is that it also causes a number of unpleasant side-effects including hallucinations and disturbed vision. A previous Good Health investigation raised concerns about its use, not least because it can be addictive.

Now researchers have discovered that nitrous oxide also acts on glutamate, but in a slightly different way, and it is hoped may have fewer side-effects. The pilot study, reported in the journal Biological Psychiatry, compared the effects of a nitrous oxide and oxygen mix against a placebo on patients with depression. The gas was inhaled for around one hour, at a dose level similar to that used by dentists as a sedative.

Results from the Washington University study in the US showed that one in three patients, who had previously tried an average of eight antidepressants each without success, responded.

Symptoms improved in two hours — whereas conventional antidepressants can take two months to have an effect — and there were no side-effects.

Now more than 200 people with different types of depression are being recruited to take part in five clinical trials at the universities of Washington and Chicago and other centres. Participants will inhale either nitrous oxide or a placebo of an oxygen and air mixture once a week for one hour for four weeks. The group assigned the nitrous oxide will be randomly given a dose of 50 per cent nitrous oxide or 25 per cent nitrous oxide.

Carmine Pariante, a professor of biological psychiatry, said: ‘The confirmation that nitrous oxide has rapid antidepressant effects is a positive development, as it confirms the importance of blocking glutamate as a way to treat depression. It offers another tool in the box for physicians.’

However, he added that nitrous oxide seemed to have some of the same side-effects as ketamine, including altered body sensations and dreamy states with altered perception of time. And he welcomed further research.