Anaesthetic may help reshape recent memories Rafael Metz / Alamy

A drug used for anaesthesia can make upsetting memories less vivid and may one day be used to help some people with post-traumatic stress disorder (PTSD).

Bryan Strange at the Technical University of Madrid in Spain and his colleagues found that when volunteers received an injection of the sedative propofol immediately after recalling a story, they remembered the story’s distressing elements less well 24 hours later.

Studies in animals have suggested that, when we retrieve a memory, there is a short window afterwards in which it is possible to modify that memory. To see if drugs may affect this, the team asked 50 volunteers to memorise two stories a week before they were due to be deeply sedated for a gastroscopy or colonoscopy.


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The participants learned the stories from slide shows that began and ended neutrally, but had upsetting content in the middle. One story was about a boy involved in a traffic accident, while the other was about the kidnapping and assault of a young woman.

Immediately before being sedated for their medical procedure, each volunteer was shown the first slide of one of the stories and asked several questions to “reactivate” their memory of the tale.

Straight after the procedure, half the participants were tested on how well they recollected the stories. Strange believes this is too soon for the memory to have been changed by the drug. The results also suggest this might be the case, because these volunteers remembered both stories equally well.

The rest of the volunteers were tested 24 hours after their procedures. Propofol did seem to have an effect: these participants were 12 per cent worse on average at remembering the emotional parts of the reactivated story compared with the non-reactivated one. They remembered the emotionally neutral parts of both stories equally well.

“The [brain] circuitry involved in emotional memory is probably quite sensitive to anaesthetics,” says Strange. “This is good for a potential treatment because you don’t want to remove information that isn’t dramatic or unwanted.”

It is possible that the drug may help to lessen the emotional impact of traumatic memories in PTSD, but it is likely to only work in some instances. Older memories are probably less changeable, says Strange, and treatment for people who have ongoing flashbacks would be more complicated.

Journal reference: Science Advances, DOI: 10.1126/sciadv.aav3801