What if you could dull the emotional pain of your worst memories?

New research from the University of Montreal suggests it's an option people might eventually have.

On Thursday, the school announced results of a study showing that the drug metyrapone could potentially "overwrite bad memories." This substance, the researchers say, reduces levels of cortisol, a stress hormone associated with memory recall.

It's theorized that by reducing a person's level of cortisol just before retrieving a memory, doctors can make the memory less painful for the person in the future.

Neurological science expert Marie-France Marin, lead author of the study, said such findings could prove beneficial for those suffering from post-traumatic stress disorder.

"These people have very bad memories that prevent them from living a normal life," she said. "We think that therapy is a good way to help with PTSD; however, for some people, it seems to not work or not be optimal.

"If every time you retrieve (a bad memory) and it's not helping you because you cannot calm down a bit and put things back into perspective, it might be a good idea to retrieve it under the influence of metyrapone so you will recall less of the emotional or very traumatic part."

She added that such therapeutic practices could lead to less painful emotions during future recollections of the memory in question.

Marin acknowledged the controversy surrounding this line of research.

"Some researchers said we're erasing memories," she said. "I think it's an overstatement. If we use it in post-traumatic stress disorder, obviously soldiers who went to Afghanistan or Iraq will remember that they went there; we're not going to erase everything.

"I think it's really reducing, modifying (and) decreasing, more than erasing. The beauty of it is that it's specific to negative information."

The potential to clear unwanted memories was the centre of the 2004 Jim Carrey movie Eternal Sunshine of the Spotless Mind, in which a couple seek to erase all recollection of their time together.

The study involved 33 healthy men between the ages of 18 and 35. They were evenly split into groups that received two doses of metyrapone, one dose of metyrapone or a placebo three days after watching a story on a computer.

After receiving the drug or placebo, participants were asked for details about the story they watched just days earlier. Subjects on the double dose of metyrapone were less able to recall negative aspects of the story.

As well, four days later, when the effects of the drug would have worn off, those who had the highest quantity of metyrapone were still less able to recall negative aspects of the tale.

One hurdle to using metyrapone this way is that it is no longer commercially produced. Marin said it used to be common for treating Cushing's disease, a condition associated with excessive levels of cortisol. She said there were no problems with the drug itself that resulted in it going off the market, but other methods for treating Cushing's disease became more widely used.

Marin agreed that any future use of this drug — or other substances with similar effects — must be done carefully.

"We have to make sure that it's taken with caution and that we don't overuse it," she said. "It's important that you live with your emotions. If you have a very bad experience — someone dies in your family — you don't necessarily want to jump on the medication.

"But for people who really suffer and cannot get out of this traumatic nightmare, I think that it offers them hope for the future."

Colin MacLeod, a psychology professor with Ontario's University of Waterloo, agreed this kind of research and its applications should be approached with caution. However, he expressed general support for it in principle.

"I think it's a perfectly worthy line of research," he said. "It could yield important theoretical and applied advances. I think we shouldn't shut down that kind of an approach . . . as long as there's no obvious harm to the individuals and we can learn something from it."

dabma@postmedia.com

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