Drug reduces the impact of traumatic memories

BBC News has a story with the headline ‘scientists can erase bad memories’, which is, at best, nonsense. What has been found is still an important discovery: a drug given during the recall of a traumatic memory can reduce its long-term emotional impact.

The drug is propranolol, a ‘beta-blocker’ that dampens down the sympathetic nervous system.

One of the roles of this system is to prepare the body for ‘flight or flight’ during stressful situations, by, among other things, releasing adrenaline, increasing blood pressure, and upping anxiety.

The drug has been used for years to help people with high blood pressure and heart conditions, so when they get stressed, it doesn’t put such a strain on their heart.

It’s been known for a while that starting a course of propranolol shortly after a traumatic event reduces the chance of people developing post-traumatic stress disorder – a condition that involves intrusive traumatic memories and hyper-arousal.

This new study is important, because it recruited people who had been traumatised a long time ago – an average of ten years earlier.

The participants were asked to recall what happened. Half were given propranolol and half were given placebo.

A week later, the participants were asked to recall the same memory while the researchers measured heart rate, sweating and muscle tension in the face – all of which are measures of bodily stress.

The participants who had been given the propranolol showed significantly less arousal than those who were given the placebo, suggesting the emotional impact of the memories had been reduced.

The fact that this can have an effect ten years after the event, if used when the memory is recalled, is an interesting finding.

Memory is a reconstructive process – in other words, our brain recreates the best estimation of an event each time we recall it. This might be slightly different each time and, importantly, each time we recall something the ‘store’ of information is changed.

It would be like if a CD remembered the other sounds in the room each time it was played, and included some of them when you listened to it again.

Propranolol might work by reducing the stress associated with the memory by influencing the ‘rewriting’ process.

The study is only a clue though. What it didn’t show is that this selectively reduced the arousal associated with that memory (maybe it affected other traumatic memories which weren’t recalled) and there was no group who were only given the drug and weren’t asked to recall anything.

It’s unlikely that the drug can reduce traumatic memories if just given at any time, but its something that needs to be explored to be sure we know how the treatment is working.

UPDATE: The Beeb have changed their headline to the slightly more sensible ‘Drug can dampen down bad memories’.

Link to abstract of scientific paper.

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