278 TREATMENT OF SPECIFIC ANXIETY DISORDERS
ways, driving in the car, walking on the street, staying alone at home, or being far away
from home are all examples of external situations that individuals with panic disorder
report may trigger a panic attack. As a result these situations are often avoided in order
to minimize the possibility of triggering a panic episode. More recently, researchers have
argued that internal cues such as thoughts, images, feelings, or bodily sensations can
trigger panic and avoidance (Barlow, 2002; McNally, 1994; White et al., 2006).
Acute Physiological Arousal
Although an abrupt onset of physiological symptoms is one of the hallmarks of panic
attacks, it is clearly not a defining feature of the disorder. Individuals with panic dis-
order are not more autonomically hyperactive to standard laboratory stressors than
nonpanickers (Taylor, 2000). Furthermore, even though 24-hour ambulatory heart rate
monitoring of panic patients indicates that most panic attacks involve a distinct eleva-
tion in heart rate, a significant minority of self- reported attacks (i.e., 40%) are not asso-
ciated with actual increase in heart rate or other physiological responses and most epi-
sodes of physiological hyperarousal (i.e., tachycardia) occur without self- reported panic
episodes (e.g., Barsky, Cleary, Sarnie, & Rushkin, 1994; Lint, Taylor, Fried-Behar, &
Kenardy, 1995; Taylor et al., 1986). Moreover, individuals with panic disorder do not
have more cardiac arrhythmias in a 24-hour period than nonpanic patients investigated
for heart palpitations (Barsky et al., 1994). As discussed below, it is not the presence of
physiological symptoms that is critical in the pathogenesis of panic but rather how these
symptoms are interpreted.
Hypervigilance of Bodily Sensations
Empirical studies are inconsistent on whether panic disorder is characterized by height-
ened interoceptive acuity especially in terms of cardiac perception (e.g., Pollock, Carter,
Amir, & Marks, 2006), although individuals may be more sensitive to the particular
body sensations linked to their central fear (e.g., increased pulse rate for those afraid of
heart attacks; Taylor, 2000). As McNally (1999) noted, fearing bodily sensations does
not mean that a person will necessarily be better at detecting interoceptive cues. On the
other hand, individuals with panic have heightened anxiety sensitivity (see Chapter 4)
and greater vigilance for the physical sensations associated with anxiety (e.g., Kroeze
& van den Hout, 2000a; Schmidt, Lerew, & Trakowski, 1997). We can conclude from
this that panic is characterized by a heightened vigilance and responsiveness to specific
physical symptoms linked to a core fear but it is unclear whether individuals with panic
disorder are better at detecting changes in their physical state.
Catastrophic Interpretations
A key feature of panic episodes is the tendency to interpret the occurrence of certain
bodily sensations in terms of an impending biological (e.g., death), mental (i.e., insanity),
or behavioral (e.g., loss of control) disaster (Beck, 1988; Beck & Greenberg, 1988; D.
M. Clark, 1986a). For example, individuals with panic disorder may interpret (a) chest
pain or a sudden increase in heart rate as sign of a possible heart attack, (b) shaking or
trembling as a loss of control, or (c) feelings of unreality or depersonalization as a sign