A drug that could erase your memories of being afraid

Scientists have known for a while that every time you retrieve a memory, you rewrite it. Remembering something is to change it, and with the help of drugs it can be changed a lot. That's the focus of research from the University of Montreal, where researchers discovered that when men who took a drug called metyrapone while remembering something painful, they couldn't recall the bad parts of the memory four days later.

This drug could be a boon to therapists trying to help people deal with trauma. But it's also terrifying when you consider how it could be used to rewrite the way people remember what's happened to them. Instead of mistrusting somebody who hurt you, you'd have nothing but neutral feelings about them. And instead of learning from your painful mistakes, you'd be left in a constant state of ill-informed naivete.

Marie-France Marin, a physiology researcher who led the study, tested the potential of metyrapone by telling a group of 33 men a story that was full of "neutral and negative events." Later, they were asked to recall the story. A third of the men recalling the story were given a dose of the drug, a third given a double dose, and a third given no dose at all. Four days after the drugging, Marin and her colleagues asked asked the men to remember the story for a second time.

Describing the results, Marin said in a release:

Metyrapone is a drug that significantly decreases the levels of cortisol, a stress hormone that is involved in memory recall. We found that the men in the group who received two doses of metyrapone were impaired when retrieving the negative events of the story, while they showed no impairment recalling the neutral parts of the story. We were surprised that the decreased memory of negative information was still present once cortisol levels had returned to normal.

Added Sonia Lupien, a psychology professor who worked with Marin on the study:

The results show that when we decrease stress hormone levels at the time of recall of a negative event, we can impair the memory for this negative event with a long-lasting effect.

Though metyrapone is no longer being manufactured commercially, Marin pointed out that other drugs have a similar cortisol-blocking effect.
"Further studies with these compounds will enable us to gain a better understanding of the brain mechanisms involved in the modulation of negative memories," Marin said.

One could easily imagine law enforcement officers or soldiers who've suffered through a terrifying situation being asked to recall it while under the influence of a metyrapone-like drug. Later, the fearful parts of the memory would fade. The question is whether the loss of these fearful memories will be a good or a bad thing. We learn to avoid dangerous situations by recalling moments of fear and pain. Indeed, our whole identities might change if we no longer remembered the things that have hurt us.

Read the full scientific article in Journal of Clinical Endocrinology and Metabolism (via Pubmed)

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