Drug Potentially "Overwrites" Bad Memories

According to a recent study, an individual recollecting memories which induce emotional pain while under the influence of a drug called metyrapone diminishes the brain’s ability to re-feel the painful emotions associated with the memory.

The study was conducted by a team of University of Montreal researchers at the Centre for Studies on Human Stress of Louis-H. Lafontaine Hospital. The object of the research was to challenge the belief that once memories are stored in the brain, they cannot be modified.

"Metyrapone is a drug that significantly decreases the levels of cortisol, a stress hormone that is involved in memory recall," said lead author Marie-France Marin. According to Marin, manipulating cortisol around the time new memories are forming can diminish the upsetting emotions potentially associated with them.

The study involved researchers assigning the task of learning a story composed of neutral and negative events, and then reliving them either under the influence of a single dose of metyrapone, a double dose of metyrapone, or a placebo.

Thirty-three men participated in the study. Three days after learning the story, they were divided into three groups: the single dose group, the double dose group, and the placebo group. After they were administered the drug or placebo, the participants were asked to recall the story.

The participants were evaluated again four days later with the same task, once the drug was no longer in their systems and cortisol levels normalized. "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."

"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.

These findings offer hope to sufferers of syndromes such as post-traumatic stress disorder. "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.

A major roadblock of this research is the fact that metyrapone is no longer commercially produced.

The findings remain promising, however, in terms of future clinical treatments. "Other drugs also decrease cortisol levels,” said Marin. “Further studies with these compounds will enable us to gain a better understanding of the brain mechanisms involved in the modulation of negative memories."

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The study is published in the Journal of Clinical Endocrinology & Metabolism.