Saturday, April 20, 2013

JOSEPH LEDOUX - For the Anxious, Avoidance Can Have an Upside


Joseph LeDoux wrote this article on anxiety recently for the New York Times' Opinionator column. He examines the use of negative reinforcement — reinforcement that occurs when a behavior prevents a stimulus from occurring — as a better form of learning. It becomes relevant in relation to trauma:
Cues associated with a trauma or other stress may start out with a narrow focus — the place where something bad happened — but may widen to include similar places, things or situations.  People with anxiety become very good at avoiding these cues as a way to control anxiety. Avoidance can be so effective that it prevents one from recovering from trauma or otherwise dealing with anxiety. 
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As we’ve seen, people with social anxiety often cope with their problem by avoiding social situations altogether. This is not practical or beneficial. But neither is forcing oneself to show up at parties and just try to ride out the anxiety. A more effective treatment approach might be to combine anxiety-producing exposure with strategies that allow one to gain control over the anxiety trigger cues.

LeDoux is a professor of neural science at New York University and director of the Emotional Brain Institute. He is the author of The Emotional Brain: The Mysterious Underpinnings of Emotional Life, Synaptic Self: How Our Brains Become Who We Are. After dark he is a singer and songwriter in The Amygdaloids.

For the Anxious, Avoidance Can Have an Upside

By JOSEPH LEDOUX
April 7, 2013

Shortly after 9/11, I wrote an editorial in the American Journal of Psychiatry with Jack Gorman, a psychiatrist with whom I was collaborating. Many people seemed to be coping with the extraordinary events of the terror attacks by staying close to home and avoiding going back out in the world. This was not unexpected since avoidance is a well-known form of coping with traumatic events. Politicians were urging people to go back to work, to re-engage in social activities, to get on with life. Gorman and I thought this was really good advice because of something I’d discovered in my work as a neuroscientist.

I had spent much of my career studying how the rat brain learns to respond to cues associated with danger. To do this, my colleagues and I presented rats with a tone followed by a mild electric shock in a conditioning box. When we presented the tone to the rat later in a different box, he would freeze in his tracks, and would continue this way even after the tone was turned off. This kind of defense response is very potent. Once the tone acquires significance as a threat, it remains so throughout the life of the rat. The learning can be weakened by exposure to the tone in the absence of the shock, but much research shows that these extinguished responses resurface if the rat is returned to the box where the shock had occurred, or is subjected to other kinds of stress.


JooHee Yoon

Exposure therapy is commonly used to treat fears in people, but as with rats, the effects are fragile. Stress, for example, can bring back successfully treated fears.

By 2001 we had already started a new line of work involving a variation on this theme. We conditioned the rat in the usual way and then a couple of days later played the tone in another box. The rat of course froze. But as soon as it made any kind of movement, the tone was turned off. The next time, more movement was required to turn the tone off. With a bit of training like this, the rat learned to run to the other side of the chamber as soon as the tone came on, escaping the tone, and eventually it learned to avoid the tone altogether by running to the other side as soon as it was in the box.

Why did the rat learn this response? Learning in animals (and people) is often based on reinforcement. So what reinforced the response? There was no shock involved in the second phase of the study. The response was learned because it eliminated the threatening tone. This is called negative reinforcement — reinforcement that occurs when a behavior prevents a stimulus from occurring.

Unlike rats that extinguish their reactions to threats by exposure, rats that had been trained to master the tone, showed no signs of being threatened by the tone later, even in the original context where the stressful shock had occurred. Once they had this kind of control, the threat was irrelevant.

We viewed this learned response where the rat takes control of the stress as a form of active coping. Gorman and I argued that getting on with life in the wake of 9/11 was like this. Each time one went to work or to meet with friends, that person moved a step away from being frozen in place, and avoiding life. It was a step toward active coping.

Cues associated with a trauma or other stress may start out with a narrow focus — the place where something bad happened — but may widen to include similar places, things or situations. People with anxiety become very good at avoiding these cues as a way to control anxiety. Avoidance can be so effective that it prevents one from recovering from trauma or otherwise dealing with anxiety.

People with social anxiety problems, for example, can easily circumvent anxiety by avoiding social situations. This solves one problem but creates others, since social interactions are an important part of daily life, including both professional and personal life. But if one is avoiding situations where these cues are likely to be encountered, the opportunity to extinguish fears by exposure never occurs and the anxiety continues indefinitely.

Yes, our rats were performing avoidance responses. They were avoiding the tone. But when avoidance involves behaviors and thoughts that directly engage with the stress-related cues and events in order to change their impact and allow the organism to exert control over them, it is useful, a form of active coping. We call this proactive avoidance. Proactive avoidance involves what has come to be known as agency. When the person gains control of situations through their own actions, anxiety diminishes.

As we’ve seen, people with social anxiety often cope with their problem by avoiding social situations altogether. This is not practical or beneficial. But neither is forcing oneself to show up at parties and just try to ride out the anxiety. A more effective treatment approach might be to combine anxiety-producing exposure with strategies that allow one to gain control over the anxiety trigger cues.

Michael Rogan, who was a researcher in my lab when the active coping work was first being done, currently treats people with social anxiety. He suggests to his clients with social anxiety that they should, when at a party, identify strategies for temporary escape and avoidance (go into the bathroom, step outside to make a call), and also use previously learned relaxation techniques (controlled breathing, imagery, mindfulness), to “chill out.” In this way, as in the rat studies, behaviors that succeed in reducing anxiety are reinforced, and each subsequent social event is a bit more tolerable.

Once the person has learned to take action rather than simply react in the presence of anxiety-provoking cues, the cues become irrelevant, as they did for the rats. Rogan says that people who learn to control anxiety triggers in this way, like our rats, do much better than those who don’t.


A New Pathway


Much has been learned about the brain mechanisms underlying passive and active coping in rats. Freezing, the rat’s version of passive coping, is known to depend on a specific set of connections in the brain — specifically, between two regions of the amygdala: the one that processes incoming signals about the external world and the one that regulates innate reactions like freezing (via outputs to the lower brainstem). The active coping response, proactive avoidance, by contrast, requires that the information processed in the input region be redirected to a different output controller in the amygdala, one that engages goal-directed actions.

While freezing is a natural first line of defense (since predators respond to movement), it can be a problem — persistent freezing prevents active coping. Indeed, some rats, like some people, have difficulty in switching from this natural and dominant tendency to freeze when action is called for. These chronically frozen rats and people are stuck in a pathological avoidance mode. If the innate output of the amygdala that controls freezing is shut down, the rats readily make the transition to proactive avoidance.

An important key to successful treatment of people with anxiety — including social anxiety — is overcoming freezing and other forms of passive coping. In our work with rats, we are seeking ways to shut down the freezing outputs of the amygdala using behavioral or drug approaches that can be safely applied to people.

A major conceptual issue is how the re-routing takes place naturally within the amygdala, allowing the shift from freezing to active coping and thereby preventing pathological avoidance and allowing proactive avoidance and agency. Recent work has shown that connections from the prefrontal cortex, a region important in behavioral control, to the amygdala are important in allowing the shift to take place.

The amygdala has long been thought of as the accelerator on the threat train, and the prefrontal cortex the brakes. But the new work suggests that the prefrontal cortex is not just the brakes, but also the switch that controls the track on which the train travels. Figuring out how to more effectively engage the prefrontal cortex in this switching will hopefully suggest new treatment approaches.

Although avoidance has a bad rep in the field of anxiety, the nature of avoidance needs to be considered when discussing its implications. When avoidance prevents one from dealing with life, it is maladaptive. But when avoidance is proactive and part of active coping and agency, it helps the person control the accelerator, brakes, and the track switches. It is a useful adaptive activity.
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