May 26

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

But its 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 studys 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

The fact that the effects of metyrapone were still evident for four days afterthats 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 didnt know whether they had taken metyrapone or the placebo, the authors note in the Journal of Clinical Endocrinology & Metabolism

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 wayprobably because cortisol levels were lower at that time

Though they predicted that people would remember the story differently while under the effects of the drug, they didnt know the memory would still be changed once hormone levels returned to normal

What was really surprising is that once the memory was sorted in the brain we were able to modify it in a long-lasting manner, Marin said

Researchers still arent sure why metyrapone might affect how negative memories, but not neutral ones, are recalled and re-stored, Marin said

The ultimate goal from this and other studies that have tried to use drugs to alter negative memories is to treat people who are overwhelmed by these memories, such as war veterans suffering from PTSDan idea that still makes some uncomfortable

According to the National Institute of Mental Health, about 35 percent of US adults suffer from PTSDbut that rate climbs to up to 20 percent in estimates of veterans of the Iraq and Afghanistan wars

PTSD is generally treated with psychotherapy, including cognitive behavioral therapy, and some people are also prescribed anti-depressants Marin said a drug like metyrapone could one day prove helpful for people who dont get better with therapy alone

But its not clear yet that a drug that helps people without PTSD remember fewer ugly details in a story will also work for those who experienced the trauma first-hand and have been profoundly affected by that trauma

We need to see if autobiographical memories are sensitive to metyrapone in the same way or not, Marin said

Whats more, only a small fraction of people exposed to traumatic events experience PTSD, Buchanan said Its hard to tell if any of those 33 volunteers might have had certain characteristics that would predispose them to PTSD or not, he said

In people with that predisposition, he said, youd imagine theres something different about their brains before the trial, which could affect how they recall negative memories

Researchers also cant be sure that women would have the same reaction to the drug as men, since only men were used in the study

Metyrapone, sold under the name Metopirone in the US, is currently not on the market, the authors note, so its important also to study other drugs that may have the same effect

More research is needed before metyrapone, or similar drugs that block cortisol, can be tested in PTSD patients But according to Buchanan, the new study is a great step in that direction

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