Inhaling laughing gas after a traumatic event reduces the later intrusion of distressing memories, new research finds.
People who inhaled nitrous oxide experienced fewer intrusive thoughts a day later, the study found.
Dr Ravi Das, the study’s first author, explained:
“The day after they saw the film, the number of intrusions experienced by the group who received nitrous oxide fell by over a half.
By contrast, the decline in intrusions was much slower in the group who received air, where there was not a significant drop in intrusions until the fourth day.
We think that this is because nitrous oxide disrupts a process that helps permanent memories to form.”
The study involved participants watching a distressing video clip.
Afterwards, half were given air, the other half a mixture containing the laughing gas.
Dr Das said:
“On any given day your brain will be exposed to a huge amount of information, some important, but most trivial.
If information is ‘important’ enough to remember, for instance because it produces a strong emotional response, it is ‘tagged’ for storage.
The brain requires N-Methyl D-Aspartate (NMDA) receptors to tag information during the day, which is then filed for long-term storage while we sleep.
We know that nitrous oxide blocks NMDA receptors, so could interfere with tagging.
This might explain why the nitrous oxide group seemed to have weaker memories of the film the day after they watched it.”
Dr Sunjeev Kamboj, one of the study’s co-authors, said:
“Nitrous oxide is routinely used as a painkiller by paramedics and in A&E departments because it is safe and easy to administer.
Many people who end up in an ambulance will have undergone some form of psychological trauma, and our study suggests that the nitrous oxide is likely to be having some effect on how their brain processes it.
However, whether it helps to prevent symptoms of PTSD or makes them more likely may depend on how dissociated patients feel before they receive it.
Further research is now needed to determine whether dissociation similarly affects the response of trauma victims who receive nitrous oxide or other painkillers such as ketamine.
It is worth noting that our volunteers were given nitrous oxide continuously for half an hour, whereas the amount that hospital patients receive will vary significantly.
Some may only receive small doses in the ambulance whereas others could be breathing it on-and-off for hours in a hospital bed.
Any effects, positive or negative, are also likely to vary depending on the dose.
The amount of nitrous oxide used recreationally in a balloon, for example, would likely be too small to have a noticeable effect on memory formation.”
The study was published in the journal Psychological Medicine (Das et al., 2016).
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