The first experimental study in humans connecting beta-blockers and memory suggests these drugs, usually taken to treat heart conditions, can also wipe away the emotions associated with frightening memories. The power of such memories could be dampened when a person thinks about the traumatic events after taking the drugs, scientists say.

Clinical psychologist Merel Kindt of the University of Amsterdam and her colleagues report the new finding online February 15 in Nature Neuroscience. The research builds on a clinical study published in the May 2008 Journal of Psychiatric Research that suggested beta-blockers helped patients suffering from post-traumatic stress disorder, PTSD.

“Kindt’s work confirms our clinical results and goes further by showing beta-blockers also have this effect” on people who had no previous history of mental health issues, comments Alain Brunet, psychiatrist at the Douglas Mental Health University Institute at McGill University in Montreal and a coauthor of the PTSD study.

Kindt and her colleagues showed subjects a photograph of a spider, which was accompanied by an electric shock, conditioning the participants to have a fearful memory of the image. Later, some participants were given a beta-blocker drug, propranolol, and others were given a placebo before being exposed to the image again. The beta-blocker group’s fear response was greatly reduced or even eliminated when the subjects were shown the spider photograph 24 hours after taking the drugs. “The people did not forget seeing the photograph of the spider,” Kindt says. ”But the fear associated with the image was erased.”

The researchers think beta-blockers work by changing the way the frightening memories are stored. Each time a memory is recalled it changes a little, and the new version is recorded in the long-term memory stash via brain chemical fluctuations in a process called reconsolidation. The beta-blockers could interfere with the brain chemicals, blocking reconsolidation of the emotional component of the memory, but leaving the rest of the memory intact, the scientists suggest.

If beta-blocker treatment were applied to people with anxiety disorders, “People would remember going through the trauma, but the emotional intensity would be dulled,” comments Karim Nader, behavioral neurobiologist at McGill University and a coauthor of the PTSD study.

Beta-blockers wouldn’t stop reconsolidation of only frightening memories, the researchers say. “It’s likely that any emotional memory, happy or sad, recalled after taking the drug would be dulled,” Kindt speculates. But patients with fear-based anxiety disorders probably aren’t thinking about the happy moments of their lives; they are obsessed with the traumatic moments, the scientists say.

Before beta-blockers can be considered a widespread treatment for anxiety disorders, the long-term effects of the drugs on memory must be assessed. But the drugs are relatively benign and already widely prescribed for other conditions, the researchers point out.

“Beta-blockers make the traumatic memories easier to deal with,” Nader says. “People can begin to talk about the traumatic event, and can even move on.”

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