Understanding Panic Disorder And Agoraphobia

Many people who develop panic disorder probably have a genetic or other biological vulnerability to the disorder.  Panic disorder runs in families (Foley et al., 2001; van den Heuvel, van de Wetering, Veltman, & Pauls, 2000).  This does not mean, of course, that panic disorders are entirely hereditary, in that family members live in the same environment.  However, the results of twin studies provide firmer evidence for an inherited predisposition for panic disorder.  Recall that identical twins share the same heredity; thus, if a disorder is transmitted entirely genetically, when one identical twin suffers from the disorder, the other twin should be highly likely to suffer from the disorder.  In contrast, fraternal twins are no more alike genetically than ordinary siblings, so that when one twin suffers from the disorder, the other twin should not be a greatly increased risk for the disorder.   Twin studies have shown than an identical twin is twice as likely to suffer panic disorder if the other twin does than is true for fraternal twins (Kendler, Neale, Kessler, & Heath, 1992, 1993; van den Heuvel et al., 2000). 

One characteristic that may be inherited in people who are prone to panic attacks is an overreactive fight-or-flight response (McNally, 2001).  A full panic attack can be induced easily by having such individuals engage in activities that stimulate the initial physiological changes of the fight-or-flight response.  For example, when people with panic disorder purposely hyperventilate, breathe into a paper bag, or inhale a small amount of carbon dioxide, they experience an increase in subjective anxiety, and many will experience a full panic attach (see Figure 15-1)  Bourin, Baker, & Bradwejn, 1998; Craske & Barlow, 2001).  In contrast, people without a history of panic attacks may experience some physical discomfort while performing these activities, but they rarely experience a full panic attack.

Figure 15-1
Panic Attacks of Patients and Control
People with panic disorder are much more likely than people without panic disorder to have a panic attack when made to hyperventilate or inhale small amounts of carbon dioxide in laboratory experiments.

This overreactive fight-or-flight response may be the result of deficiencies in areas of the brain that regulate this response, especially the limbic system (Deakin & Graeff, 1991; Gray, 1982; Reiman, Lane, Ahern, Schwartz, & Davidson, 2000).  Some studies show that people with panic disorder have low levels of the neurotransmitter serotonin in the limbic system and other brain circuits involved in the fight-or-flight response (Bell & Nutt, 1998).  Serotonin deficiencies cause chronic hyperactivities of these areas of the brain, putting the individual on the verge of a panic attack most of the time.

An overreactive fight-or-flight response may not be enough to create a full panic disorder, however.  Cognitive behavioral theories of panic and agoraphobia suggest that people who are prone to panic attacks tend to pay very close attention to their bodily senssations, misintrepret bodily sensation in a negative way, and engage in atrophic thinking (Bouton, Mineka, & Barlow, 2001; Clark, 1988; Craske & Barlow, 2001).  In the case described earlier, when Hazel felt her muscles tightening, she began thinking, “I’m having a heart attack!  I’m going to die!”  Not surprisingly, these thoughts increased her emotional symptoms of anxiety, which in turn made her physiological symptoms worse – her heart rate increased even more, and her muscles felt even tighter.  Interpreting these physiological changes catastrophically led to a full panic attack.  Between attacks, Hazel is hyper vigilant, paying close attention to any bodily sensation.  Her constant vigilance causes her autonomic nervous system to be chronically aroused, making it more likely that she will have another panic attack.

How does agoraphobia develop out of panic disorder?  According to the  cognitive-behavioral theory, people with panic disorder remember vividly the places where they have had attacks.  The greatly fear those places, and that fear generalizes to all similar places  By avoiding those places, they reduce their anxiety, and their avoidance behavior thus is highly reinforced.  They may also find that they experience little anxiety in particular places, such as their own homes, and this reduction of anxiety is also highly reinforcing, leading them to confine themselves to these “safe” places.  Thus, through classical and operant conditioning, their behaviors are shaped into what we call agoraphobia.

What evidence is their for this theory:  Several laboratory studies support the contentions that cognitive factors play a strong role in panic attacks and that agoraphobic behaviors may be conditioned through learning experiences (McNally, 2001).  In one study, researchers asked two groups of patients with panic disorder to wear masks through which they would inhale slight amounts of carbon dioxide.  Both groups were told that, although inhaling a slight amount of carbon dioxide was not dangerous to their health, it can induce a panic attack. 

One group was told that they could not control this amount of carbon dioxide that came through their masks.  The other group was told that they could control how much carbon dioxide they inhaled by turning a knob.  Actually, neither group had any control over the amount of carbon dioxide they inhaled, and both groups inhaled the same amount.   Eighty percent of the patients who believed that they had no control experienced a panic attack, but only 20 % of those who believed that they could control the carbon dioxide had an attack.  These results clearly suggest that beliefs about control over panic symptoms play a strong role in panic attacks (Sanderson, Rapee, & Barlow, 1989).

In a study focusing on agoraphobic behaviors, researchers examined whether people with panic disorder could avoid having a panic attack,  even after inhaling carbon dioxide, by having a “safe person” nearby.  Panic patients who were exposed to carbon dioxide with their safe person present were much less likely to experience the emotional, cognitive, and physiological symptoms of panic than panic patients who were exposed to carbon dioxide with their safe person present (see Figure 15-2; Carter, Hollon, Caron, & Shelton, 1995).  These results show that the symptoms of panic become associated with certain situations and the operant behaviors such as sticking close to a “safe person” can be reinforced by the reduction of panic symptoms.

Figure 15-2
Panic Symptoms in Panic Patients With and Without a Safe Person Available
Panic patients were much more likely to show symptoms of panic when a sfe person was not with them.

Figure 15-3
A Vulnerability-Stress Model of Panic and Agoraphobia
A combination of biological vulnerability to an overreactive fight-or-flight response plus cognitive vulnerability to catastrophizing cognitions may begin a chain of processes leading to panic and agoraphobia.

The biological and cognitive-behavioral theories of panic disorder and agoraphobia thus can be intergrated into a vulnerability-stress model (Craske & Barlow, 2001; see Figure 15-3).  People who develop panic disorder may have a genetic or biochemical vulnerability to an overreactive fight-or-flight response, so that even with only a slight triggering stimulus, their bodies experience all the physiological symptoms of the response.  For a full panic disorder to develop, however, it may be necessary for these individuals to also be prone to catatrophizing these symptoms and worrying excessively about having panic attacks.  These cognitions further heighten their physiological reactivity, making it even more likely that they will experience a full fight-or-flight response.  Agoraphobia develops when they begin to avoid places that they associate with their panic symptoms and confine themselves to places where they experience less anxiety.  This vulnerability-stress model has led to exciting breakthroughs in the treatment of panic disorder and agoraphobia, which we will discuss in Chapter 16.

Chapter 14
Psychological Reactions To Stress
Understanding Panic Disorder And Agoraphobia

Atkinson & Hilgard’s
Introduction To Psychology
14th Edition

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