Neuroscientists work to eradicate phobias and anxiety, one bad memory at a time
One winter evening, Etelle Higonnet and a friend were driving back from a Vermont ski trip when they stopped for fuel. They gassed up and bought a bag of M&M’s, then hit the road again. The journey was going smoothly until the car hit a patch of ice and skidded across several lanes of traffic, flipping over multiple times. Miraculously, the women walked away from the accident with only a few bruises.
The next night, they met up at a movie theater. When Higonnet walked past the snack counter, she caught a glimpse of some M&M’s. Suddenly, she began to shake and cry and fell to the floor in a full-blown panic attack.
Like all emotional experiences, trauma is encoded in the brain. The extra adrenaline that accompanies terrifying events inks those memories in boldface, making anxieties and phobias difficult to shake. As University of Virginia psychologist Bethany Teachman puts it, “We often say that we can get two-thirds of [anxiety patients] two-thirds of the way better.”
Through much of the 20th century, scientists thought the brain’s physical structure couldn’t change significantly after childhood. But recently, researchers have discovered that the adult brain can reprogram itself at any age—whether it’s learning multiplication tables, mastering chess, or relearning how to walk after a stroke. Scientists call the brain’s ability to be reshaped neuroplasticity.
Is it possible to exploit the brain’s malleability to treat serious anxiety disorders? Yes, says John Krystal, chief of psychiatry at the Yale School of Medicine. Krystal believes that the aim of managing anxiety shouldn’t be to erase awful memories, but rather to blunt their damaging effects. One way to do that is to establish new memories that crowd out the painful ones—like falling off your bike and then continuing to ride it afterward. Eventually you build up enough happy memories to make you stop thinking about the time you fell.
A growing body of research suggests that a drug called D-cycloserine, an antibiotic sometimes used to treat tuberculosis, may expedite the process of building new memories. D-cycloserine greases the skids for glutamate—a neurotransmitter in the brain that makes it possible to weed out fear memories—kind of like a memory lubricant. It doesn’t alter bad memories, but it makes it easier to forge new, more comfortable memories around them.
In a 2004 study led by neuroscientists Kerry Ressler and Barbara Rothbaum, 30 acrophobic volunteers confronted their fear of heights. The patients wore virtual-reality helmets that simulated riding in a glass elevator to the top of a tall building. Some of the patients were given D-cycloserine before the sessions; others received a placebo. The patients who took D-cycloserine were significantly less afraid during the simulations, and three months later they showed the same level of improvement. Since then, researchers have found similar results using D-cycloserine to treat social anxiety disorder, panic disorder, obsessive-compulsive disorder, and post-traumatic stress disorder.
While D-cycloserine presents exciting potential in the fight against anxiety, it still requires layering new memories on top of old ones. But what if you could alter the painful memory itself? Recent research shows that memory is more malleable than previously believed, and studies indicate that recalling a memory opens a brief window of opportunity to alter it. This process of retrieving a memory and then changing it is called reconsolidation. Harvard psychiatrist Roger Pitman likens memory reconsolidation to a file in an office cabinet: If you want to adjust the contents, first you have to retrieve the file. But you can only make changes when it’s open.
In 2009 neuropsychologists confirmed that if you activate a person’s fear, the traumatic memories associated with it can, for a brief period, be altered. The key is to provide complete safety during the reconsolidation window—which, in humans, opens up about 10 minutes after a memory is recalled. The window lasts up to six hours, then slams shut until the next time the memory is recalled.
This discovery could completely change the way psychological therapy is conducted. Right now, therapists don’t usually monitor what happens to a patient in the hours following a therapy session. But with a new understanding of how fear memories are created, timing may be everything.
Siri Carpenter is a science journalist with doctoral training in social psychology who has written for the New York Times, the Los Angeles Times, Scientific American Mind, Science News, and other publications. Excerpted from Mental Floss (March-April 2011), the magazine “where knowledge junkies get their fix.”www.mentalfloss.com