New York - Blocking a hormone involved in the body's response to stress may change the way people recall negative memories, said a study.
But it's still unclear exactly how the drug works, and whether it has implications for the treatment of conditions such as post-traumatic stress disorder (PTSD), according to the study, which appeared in the Journal of Clinical Endocrinology & Metabolism.
The drug, metyrapone, blocks the stress hormone cortisol and has been used to treat people with diseases related to cortisol production.
Cortisol is also involved in storing and retrieving memories, though, making researchers wonder if tinkering with its levels could change how people recall past events.
“We know that (cortisol) is important for memory,” said Marie-France Marin, the study's lead author from the University of Montreal.
“Very high levels are bad for your memory, and very low levels are bad for your memory,” she told Reuters Health.
Marin and her colleagues used metyrapone to stop healthy volunteers from producing cortisol.
The volunteers, 33 young men, were first shown a narrated slide show that had both “neutral” and “emotionally negative” slides about a young girl at her grandparents' house who is badly injured. Scenes showed a lot of blood and a trip to the operating room, though at the end viewers knew she would be okay.
Three days after watching the show, 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 more drugs, asked them to recall the story again.
There was no difference in how men who had taken a single does of the drug and those given the placebo remembered the story either time. But on both occasions, those given a double does remembered significantly less of the negative emotional components of the story.
“The fact that the effects of metyrapone were still evident for four days after - that's pretty remarkable,” said Tony Buchanan, who studies stress and memory at Saint Louis University, to Reuters Health.
Both metyrapone groups still recalled the “neutral” information as well as the placebo group did.
Marin and her colleagues believe that once participants were asked to retrieve the memory of the story, those taking the high dose of metyrapone re-stored that memory in a different, less emotional way - probably because cortisol levels were lower at that time.
What surprised them was that the memory would still be changed when hormone levels returned to normal, and she said that her team still wasn't sure why it only affected negative memories.
The goal of such research would be something that might help treat PTSD that doesn't resolve with psychotherapy. About 3.5 percent of US people suffer from PTSD, with estimates of up to 20 percent of veterans of the Iraq and Afghanistan wars, according to the National Institute of Mental Health.
More research is needed - to see if women would have the same response as men, or to study other drugs that might have the same affect. Metyrapone is currently not on the market.
“We need to see if autobiographical memories are sensitive to metyrapone in the same way or not,” Marin said. - Reuters