A team of Dutch researchers under the leadership of Vici-winner Merel Kindt has successfully reduced the fear response. They weakened fear memories in human volunteers by administering the beta-blocker propranolol. Interestingly, the fear response does not return over the course of time. Top journal Nature Neuroscience published the findings on 15 February 2009.
Until recently, it was assumed that the fear memory could not be deleted. However, Klindt's team has demonstrated that changes can indeed be effected in the emotional memory of human beings.
The researchers found that if they caused humans to remember a fearful memory (seeing a picture of a spider and at the same moment feeling pain) and administered propranolol that reduced the fear response when spider pictures were shown again at a later date.
The memory of connections between two events were still recallable but no longer elicited the feeling of fear.
Interestingly, after the treatment with propranolol and memory reactivation, fear memories can no longer be recalled by means of a much-used method in which the individual pain stimuli are readministered. This indicates that the anxiety memory is either completely erased or could no longer be found in the memory. It should be noted, however, that the human volunteers could remember the association between the spider and the pain stimulus but that this no longer elicited any emotional response. In the next phase of the research, Kindt and her colleagues shall investigate the long-term effects of administering propranolol.
Got any fear response you want to dampen down?
I wonder what would happen if people were shown a politician's picture while someone described a policy that they feared. Would they lose their fear of higher taxes or their fear of a reduction of the welfare state? Could people be conditioned to accept (or object less strongly to) policies that they currently oppose? Could captured spies get treated with propranolol to reduce their fear of what happens should they divulge secret information while undergoing interrogation?
Philadelphia, PA, 17 March 2009 – Imagine that you have been in combat and that you have watched your closest friend die in front of you. The memory of that event may stay with you, troubling you for the rest of your life. Posttraumatic stress disorder (PTSD) is among the most common and disabling psychiatric casualties of combat and other extremely stressful situations. People suffering from PTSD often suffer from vivid intrusive memories of their traumas. Current medications are often ineffective in controlling these symptoms and so novel treatments are needed urgently. In the February 1st issue of Biological Psychiatry, published by Elsevier, a group of basic scientists shed new light on the biology of stress effects upon memory formation. In so doing, they suggest new approaches to the treatment of the distress related to traumatic memories. Their work is based on the study of a drug, RU38486, that blocks the effects of the stress hormone cortisol.
Using an animal model of traumatic memory, investigators at the Mount Sinai School of Medicine show that treatment with RU38486 selectively reduces stress-related memories, leaving other memories unchanged. They also found that the effectiveness of the treatment is a function of the intensity of the initial "trauma." Although this particular study was performed in rats, their findings help to set the stage for trials in humans. Cristina Alberini, Ph.D., corresponding author on this article, explains how their findings will translate into developing clinical parameters: "First, the drug should be administered shortly before or after recalling the memory of the traumatic event. Second, one or two treatments are sufficient to maximally disrupt the memory. Third, the effect is long lasting and selective for the recalled memory. Finally, the time elapsing between the traumatic experience and the treatment seems to be an important parameter for obtaining the most efficacious treatment."
Drugs that selectively eliminate some of our memories and emotional reactions appear to be well within the realm of the possible. Therefore we'll have such drugs some day.
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