Nitrous Oxide Could Reduce Bad Memories
Post-traumatic stress disorder (PTSD) is more common that you might think. It affects around 5% of men and 10-12% of women after a catastrophic event. Rates are particularly high among rape victims, 60-80% of whom experience PTSD.
Now research published in Psychological Medicine suggests that receiving nitrous oxide after a traumatic event may help to reduce the incidence of distressing memories.
The study involved 50 healthy adult volunteers and was overseen by both a trained clinical psychologist and a medical doctor. They asked participants to watch two graphic scenes from the 2002 movie, "Irreversible," once described as "so violent and cruel that most people will find it unwatchable."
After watching the clips, the participants were given a gas to breathe for 30 minutes. Half of them breathed a 50-50 mix of nitrous oxide and oxygen; the others received medical air.
Over the following week, the participants kept a daily record of intrusions related to the movie clips. Intrusions are involuntary, distressing, memories that flash into the mind after a distressing event.
Inhaling nitrous oxide after watching the clips was linked to a much faster decline in the incidence of distressing memories. The day after viewing, the number of intrusions fell by 50%, and intrusions declined exponentially over the following week. In contrast, the people who breathed normal air experienced a slower, more gradual and linear decline. A significant drop did not occur until day four.
Throughout our days, certain memories are “tagged” in our brain. Tagging is carried out by N-Methyl D-Aspartate (NMDA) receptors in the brain. Tagged information is then filed for long-term storage as we sleep. Nitrous oxide blocks NMDA receptors, which could mean that it hinders tagging and leaves weaker memories.