Who among us hasn’t wanted to let go of anxiety or forget about fear? Phobias, panic attacks and disorders like post-traumatic stress are extremely common: 29 percent of American adults will suffer from anxiety at some point in their lives.
Sitting at the heart of much anxiety and fear is emotional memory — all the associations that you have between various stimuli and experiences and your emotional response to them. Whether it’s the fear of being embarrassed while talking to strangers (typical of social phobia) or the dread of being attacked while walking down a dark street after you’ve been assaulted (a symptom of PTSD), you have learned that a previously harmless situation predicts something dangerous.
It has been an article of faith in neuroscience and psychiatry that, once formed, emotional memories are permanent. Afraid of heights or spiders? The best we could do was to get you to tolerate them, but we could never really rid you of your initial fear. Or so the thinking has gone.
The current standard of treatment for such phobias revolves around exposure therapy. This involves repeatedly presenting the feared object or frightening memory in a safe setting, so that the patient acquires a new safe memory that resides in his brain alongside the bad memory. As long as the new memory has the upper hand, his fear is suppressed. But if he is re-traumatized or re-exposed with sufficient intensity to the original experience, his old fear will awaken with a vengeance.
This is one of the limitations of exposure therapy, along with the fact that it generally works in only about half of the PTSD patients who try it. Many also find it upsetting or intolerable to relive memories of assaults and other traumatizing experiences.
We urgently need more effective treatments for anxiety disorders. What if we could do better than creating a new safe memory — and actually get rid of emotions attached to the old bad one?
New research suggests that it may be possible not just to change certain types of emotional memories, but even to erase them. We’ve learned that memories are uniquely vulnerable to alteration at two points: when we first lay them down, and later, when we retrieve them.
Merel Kindt, a professor of psychology at the University of Amsterdam, and her colleagues have seemingly erased the emotional fear response in healthy people with arachnophobia. For a study published last month in the journal Biological Psychiatry, she compared three groups made up of 45 subjects in total. One group was exposed to a tarantula in a glass jar for two minutes, and then given a beta-blocker called propranolol that is commonly prescribed to patients for performance anxiety; one was exposed to the tarantula and given a placebo; and one was just given propranolol without being shown the spider, to rule out the possibility that propranolol by itself could decrease spider fear.
Dr. Kindt assessed the subjects’ anxiety when they were shown the spider the first time, then again three months later, and finally after a year. What she found was remarkable. Those who got the propranolol alone and those who got the placebo had no improvement in their anxiety. But the arachnophobes who were exposed to the spider and given the drug were able to touch the tarantula within days and, by three months, many felt comfortable holding the spider with their bare hands. Their fear did not return even at the end of one year.
How does this work? Well, propranolol blocks the effects of norepinephrine in the brain. This chemical, which is similar to adrenaline, enhances learning, so blocking it disrupts the way a memory is put back in storage after it is retrieved — a process called reconsolidation.
Arachnophobes have an emotional memory that involves an association between spiders and a dreaded outcome, like a spider bite. This “fear memory” is the source of their phobia — even if (as is often the case) it never actually happened. The basic idea is that when Dr. Kindt briefly exposed the subjects to the spider, she reactivated their fear, which made the fear memory susceptible to the influence of propranolol.
Reconsolidation is a bit like pulling up a file on your computer, rewriting the same material in a bigger, bolder font and saving it again. Disrupting reconsolidation with propranolol or another drug is akin to retrieving this document, erasing some or all of the text and then writing something new in its place.
Dr. Kindt is not the first to demonstrate that disrupting reconsolidation can weaken or erase emotional memories. Several studies of rats done in 2000 showed that a drug called anisomycin, which blocks the synthesis of proteins in the brain, could reduce fear associations. In one, researchers taught rats to fear a sound by pairing it with a shock. After the animals were fear-conditioned, they were presented with the sound and then immediately given the drug. When the animals were exposed to the sound again, they no longer appeared afraid; they had forgotten their original fear.
Curiously, there is a very narrow time window after retrieving a fear memory when you can disrupt that memory — hours, in the animal studies — before it closes and the drug has no effect.
These studies suggest that someday, a single dose of a drug, combined with exposure to your fear at the right moment, could free you of that fear forever. But there’s a flip side to this story about how to undo emotional learning: how to strengthen it. We can do that with drugs as well, and may have been doing it for some time.
by Richard A. Friedman , NY Times | Read more:
Image: Jillian Tamaki
Sitting at the heart of much anxiety and fear is emotional memory — all the associations that you have between various stimuli and experiences and your emotional response to them. Whether it’s the fear of being embarrassed while talking to strangers (typical of social phobia) or the dread of being attacked while walking down a dark street after you’ve been assaulted (a symptom of PTSD), you have learned that a previously harmless situation predicts something dangerous.
It has been an article of faith in neuroscience and psychiatry that, once formed, emotional memories are permanent. Afraid of heights or spiders? The best we could do was to get you to tolerate them, but we could never really rid you of your initial fear. Or so the thinking has gone.
The current standard of treatment for such phobias revolves around exposure therapy. This involves repeatedly presenting the feared object or frightening memory in a safe setting, so that the patient acquires a new safe memory that resides in his brain alongside the bad memory. As long as the new memory has the upper hand, his fear is suppressed. But if he is re-traumatized or re-exposed with sufficient intensity to the original experience, his old fear will awaken with a vengeance.
This is one of the limitations of exposure therapy, along with the fact that it generally works in only about half of the PTSD patients who try it. Many also find it upsetting or intolerable to relive memories of assaults and other traumatizing experiences.
We urgently need more effective treatments for anxiety disorders. What if we could do better than creating a new safe memory — and actually get rid of emotions attached to the old bad one?
New research suggests that it may be possible not just to change certain types of emotional memories, but even to erase them. We’ve learned that memories are uniquely vulnerable to alteration at two points: when we first lay them down, and later, when we retrieve them.
Merel Kindt, a professor of psychology at the University of Amsterdam, and her colleagues have seemingly erased the emotional fear response in healthy people with arachnophobia. For a study published last month in the journal Biological Psychiatry, she compared three groups made up of 45 subjects in total. One group was exposed to a tarantula in a glass jar for two minutes, and then given a beta-blocker called propranolol that is commonly prescribed to patients for performance anxiety; one was exposed to the tarantula and given a placebo; and one was just given propranolol without being shown the spider, to rule out the possibility that propranolol by itself could decrease spider fear.
Dr. Kindt assessed the subjects’ anxiety when they were shown the spider the first time, then again three months later, and finally after a year. What she found was remarkable. Those who got the propranolol alone and those who got the placebo had no improvement in their anxiety. But the arachnophobes who were exposed to the spider and given the drug were able to touch the tarantula within days and, by three months, many felt comfortable holding the spider with their bare hands. Their fear did not return even at the end of one year.
How does this work? Well, propranolol blocks the effects of norepinephrine in the brain. This chemical, which is similar to adrenaline, enhances learning, so blocking it disrupts the way a memory is put back in storage after it is retrieved — a process called reconsolidation.
Arachnophobes have an emotional memory that involves an association between spiders and a dreaded outcome, like a spider bite. This “fear memory” is the source of their phobia — even if (as is often the case) it never actually happened. The basic idea is that when Dr. Kindt briefly exposed the subjects to the spider, she reactivated their fear, which made the fear memory susceptible to the influence of propranolol.
Reconsolidation is a bit like pulling up a file on your computer, rewriting the same material in a bigger, bolder font and saving it again. Disrupting reconsolidation with propranolol or another drug is akin to retrieving this document, erasing some or all of the text and then writing something new in its place.
Dr. Kindt is not the first to demonstrate that disrupting reconsolidation can weaken or erase emotional memories. Several studies of rats done in 2000 showed that a drug called anisomycin, which blocks the synthesis of proteins in the brain, could reduce fear associations. In one, researchers taught rats to fear a sound by pairing it with a shock. After the animals were fear-conditioned, they were presented with the sound and then immediately given the drug. When the animals were exposed to the sound again, they no longer appeared afraid; they had forgotten their original fear.
Curiously, there is a very narrow time window after retrieving a fear memory when you can disrupt that memory — hours, in the animal studies — before it closes and the drug has no effect.
These studies suggest that someday, a single dose of a drug, combined with exposure to your fear at the right moment, could free you of that fear forever. But there’s a flip side to this story about how to undo emotional learning: how to strengthen it. We can do that with drugs as well, and may have been doing it for some time.
by Richard A. Friedman , NY Times | Read more:
Image: Jillian Tamaki
