Beta-blocker drugs can wipe away emotions associated with frightening memories, Dutch research shows. The drugs are usually taken to treat heart conditions.
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 co-author of the PTSD study.
Experiments on animals had already shown that the drugs - beta-adrenergic receptor blockers - can interfere with how the brain makes and remakes memories of frightening events.
In the latest study, Dr Merel Kindt of Amsterdam University tested the drugs on 60 men and women.
Her team created fearful memories in volunteers by showing them pictures of spiders while giving them gentle electric shocks.
The volunteers were urged to 'actively remember' the images, creating a strong negative association between spiders and discomfort.
The following day the volunteers were split into two groups. One was given the beta blocker and the other a placebo pill before both were shown the same spider pictures.
The researchers recorded the level of fear in the volunteers by playing sudden noises and measuring how strongly they blinked.
A strong startle response showed they were in a fearful state, while a mild response showed they were calm.
A day later - once the drug was out of their systems - their fear response was tested again.
Once more, those given the beta blocker the previous day showed fewer signs of spider phobia, suggesting the memory was completely 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 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, Solmaz Barazesh writes on Science News.
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 say.
"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."
But others have raised concerns. Dr Daniel Sokol, a lecturer in medical ethics at St George's, University of London, said: 'Removing bad memories is not like removing a wart or a mole. It will change our personal identity since who we are is linked to our memories.
'It may perhaps be beneficial in some cases, but before eradicating memories, we must reflect on the knock-on effects that this will have on individuals, society and our sense of humanity.'