10 December 2009

Fearful memories defanged

A new study suggests that people might be able to reduce the power of fearful memories that cause physical symptoms when they're triggered.


A new study suggests that people might be able to reduce the power of fearful memories that cause physical symptoms when they're triggered.

The research is preliminary, and study co-author Elizabeth Phelps cautioned that it doesn't provide an immediate cure for such conditions as anxiety and post-traumatic stress disorder. But it does offer some hope for new ways to treat them in the future, said Phelps, who directs a laboratory at New York University's psychology department.

The key, she said, is to interfere with a memory "at a particular time when we know it may be vulnerable or susceptible to being changed."

Emotional fear

The memories in question link an emotional fear to a physical response, she said.

For example, imagine you are bitten by the pit bull next door, and then you come across the dog again. You'll have a memory of the incident, Phelps said, but also possibly another kind of memory that will kick in a physical reaction.

"You'll start to tense up, sweat a little and your heart will race," she said. "That's the memory we're talking about."

This kind of "fear memory" is stored in a different part of the brain than the actual memory of the event that triggered it, she said.

In people with anxiety problems and post-traumatic stress disorder, such memories can lead to major trouble.

Influence memories

Phelps and her colleagues suspected that there are times when the memories are susceptible to influence. They tested their theories and report their findings in an issue of Nature.

The researchers instilled fear memories in study participants by shocking them when they saw certain visual images. The idea was to make them develop a fear memory connected to the image and then see if they could undo it.

The researchers found that they could defang the memory a day later by convincing a person that the images were safe. They found they could do this by acting quickly after the images triggered the response, Phelps said.

Brain overwrites memory

Essentially, the brain appears to be able to overwrite the memory during a short time period, she said.

In the big picture, the research "might help us develop interventions that are more long-lasting, more effective in the long term" than current ones, she said.

Joy Hirsch, director of Columbia University Medical Center's program for imaging and cognitive sciences, said the research provides "a fundamental basis to be hopeful that one's fears and anxieties that are the result of traumatic memories can be resolved."

The focus "is not on natural degeneration of a memory, which would be forgetting," she said. "The focus is in changing the memory in some way not to falsify it. You call it up, and you interject something or you modify the way you think about it. You change it in some way; then it reconsolidates."

But couldn't changing memories be dangerous?

"Everything we understand about how memory works will help us manipulate memories," Phelps said. "And that can be used for good or evil." - (Randy Dotinga/HealthDay News, December 2009)


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