Recalling a painful memory while under the influence of the drug metyrapone reduces the brain’s ability to re-record the negative emotions associated with them, say University of Montreal researchers. The team’s study challenges the theory that memories cannot be altered once they are stored in the brain.
Said lead author Marie-France Marin:
“Metyrapone is a drug that significantly decreases the levels of cortisol, a stress hormone that is involved in memory recall.”
Manipulating cortisol close to the time of forming new memories can decrease the negative emotions that may be associated with them.
“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,” said Dr. Sonia Lupien, who directed the research.
Thirty-three men participated in the study. In the study, the men were asked to learn a story composed of neutral and negative events.
Three days later, the participants were divided into three groups. Participants in the first group received a single dose of metyrapone, the second received double, while the third were given placebo.
They were then asked to remember the story. Their memory performance was then evaluated again four days later, once the drug had cleared out.
“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,” Marin explained. “We were surprised that the decreased memory of negative information was still present once cortisol levels had returned to normal.”
“Our findings may help people deal with traumatic events by offering them the opportunity to ‘write-over’ the emotional part of their memories during therapy,” Marin said.
One major hurdle, however, is the fact that metyrapone is no longer commercially produced. Nevertheless, the findings are very promising in terms of future clinical treatments.
“Other drugs also decrease cortisol levels, and further studies with these compounds will enable us to gain a better understanding of the brain mechanisms involved in the modulation of negative memories.”