Memory surgery: common drug takes the panic out of traumatic memories
February 17, 2009 Memory-induced panic attacks can be absolutely crippling for sufferers of post-traumatic stress disorder (PTSD) - the suffocating, gripping fear associated with traumatic memories can destroy victims' careers, relationships and the normal functioning of their lives. But a team of Dutch clinical psychologists are developing an almost magical cure, using a single dose of a common and fairly harmless beta-blocking drug that seems to be able to separate the panic emotion from the factual elements of the memory - leaving patients with an apparently lasting ability to recall and talk about the traumatic incident without the usual devastating rush of fear.
Memories of extreme trauma seem to be formed in a different way to normal memories. As the brain reels with the stress of the initial incident, the rush of stress and fear hormones seem to cause a different type of memory encoding, which can resurface for years afterward as an intense emotional connection that floods the body whenever the memory is recalled. PTSD victims experience this in a very physical and terrifying fashion.
Breaking the cycle: reconsolidation
But it turns out that each time a memory is recalled and thought about, the brain actually re-stores it. It's at this crucial "reconsolidation" phase that the memory can be separated from the fight-or-flight hormone rush that is so debilitating for victims.
Merel Kindt and her team at the University of Amsterdam have been working to develop an understanding of how the common beta-blocker propranolol seems to be able to interrupt the stress hormone encoding as a memory is being reconsolidated - leaving the memory apparently unaltered but removing the panic response.
The most effective technique seems to be to give patients a dose of propranolol - commonly used to treat hypertension, angina and cardiac arrhythmia - then, as the drug takes effect, reactivating the memory, stress effects and all. When the memory is re-encoded, the beta-blocking action of propranolol seems to prevent the re-storage of the emotional stress portion of the memory.
Kindt's team are clinically testing the drug using an induced panic reaction associated with spiders in test subjects. On day 1, subjects were repeatedly shown photos of spiders, and were given an "uncomfortable" electric shock.
On day 2, the subjects were given either propranolol or a placebo, and were then shown the same images. Both the control and experimental groups shows a physical stress and fear reaction to the photos.
On day 3, the subjects were shown the same photos - and there was a noticeable reduction in fear symptoms shown by the group given propranolol. What's more, subjects that were given propranolol but that weren't subjected to the reconsolidation process on day 2 didn't appear to benefit from the drug, suggesting that the reconsolidation process is where the drug takes effect.
Legal and ethical implications
If propranolol or another drug proves able to assist in a kind of "memory surgery" - and thus has the ability to vastly improve the lives of PTSD and panic attack sufferers - surely it should be used to this effect. PTSD, by its nature, tends to affect innocent victims of tragic and traumatic events, and if the technology exists to reduce the burden of panic attacks for these victims, then it should be deployed.
But the association of fear with certain memories is also a valuable learning tool that can help prevent people from getting into trouble situations again - so, while the soldier on deployment in Iraq might suffer from PTSD after a terrifying incident, that fear might help save his life in a future situation.
There's also potential legal ramifications, wherein a defendant in a sexual abuse case might be able to argue that a victim makes an unreliable witness because they have chosen to alter their memory using this sort of technology.
But surely the victim's quality of life is more important than the punishment of the perpetrator - and the psychological devastation that arises in the aftermath of events like Hurricane Katrina or the recent Australian bushfires can be a crippling hindrance to survivors' ability to rebuild their lives and get on with it.
Either way, the ability to permanently cure or dampen the fear of memory-linked panic attacks is a fascinating piece of psychological technology and we look forward to the results of future studies with great interest.
Read Prof. Dr. Kindt's full experimental report over at Nature Neuroscience.