Drug may take the edge off bad memories: study

Blocking a hormone involved in the body's stress response may change the way people remember negative memories, according to a new study.

But it's still unclear exactly how the drug involved works, and if the finding has implications for the treatment of people with conditions like post-traumatic stress disorder (PTSD).

The drug, metyrapone, blocks the stress hormone cortisol and has been used to treat people with diseases related to cortisol production.

But cortisol is also involved in storing and retrieving memories, leading researchers to wonder if tinkering with its levels in the body could change how people recall past events.

"We know that (cortisol) is important for memory," Marie-France Marin, the study's lead author from the University of Montreal, told Reuters Health. "Very high levels are bad for your memory, and very low levels are bad for your memory," she explained.

In their research, Marin and her colleagues went for the very low levels, using metyrapone to stop healthy volunteers from producing cortisol.

Those volunteers, 33 young men, were first shown a narrated slide show that had both "neutral" and "emotionally negative" slides.

The slides told the story of a young girl who goes to her grandparents' house. There, she and her grandparents try to build a birdhouse, and the girl gets badly injured, with scenes showing lots of blood and a trip to the operating room. In the end, viewers know that the girl will be okay.

Three days after watching the video, researchers gave the men either a single 750-milligram dose of metyrapone, a double dose, or a drug-free placebo pill. Then they asked them to recall as much information as possible from the story.

Another four days after that, they brought the participants in once more, and without giving them any drugs asked them to recall the story again.

There was no difference in how men who had taken a single dose of metyrapone and those given a placebo remembered the story either time.

But on both occasions, those given a double dose remembered significantly less of the negative emotional components of the story.

For example, men in the placebo group scored between 40 and 50 percent on their second memory test for negative emotional information in the story, compared to about 30 percent in the group given a double metyrapone dose.

"The fact that the effects of metyrapone were still evident for four days after - that's pretty remarkable," Tony Buchanan, who studies stress and memory at Saint Louis University and was not involved in the study, told Reuters Health.

Both metyrapone groups still recalled the "neutral" information as well as the placebo group.

The investigators who determined how much participants remembered didn't know whether they had taken metyrapone or the placebo, the authors note in the Journal of Clinical Endocrinology & Metabolism.