THE EFFECTS OF EXTRAVERSION ON PANIC SENSATIONS AND PANIC-FEAR COGNITIONS
INDUCED BY A 35% CO2 CHALLENGE
Todd Kashdan, Jillian C. Shipherd, and J. Gayle Beck
State University of New York at Buffalo
A Poster Presented at the 33rd Annual Convention of the Association for the Advancement of Behavior
Therapy (AABT) on November 12, 1999 in Toronto.
THE EFFECTS OF EXTRAVERSION ON PANIC SENSATIONS AND PANIC-FEAR COGNITIONS
INDUCED BY A 35% CO2 CHALLENGE
Todd Kashdan, Jillian C. Shipherd, and J. Gayle Beck
State University of New York at Buffalo
Abstract
The present study examined the interrelationship between anxious responding to a CO 2 challenge
and personality in Panic Disorder (PD) patients and matched controls (MC). Our hypotheses predicted that
fearful responding would be negatively correlated with extraversion and positively correlated with
neuroticism, irrespective of group membership. Contrary to our hypothesis, significant group differences
emerged. Individuals scoring low in extraversion in the MC group had more intense panic-fear reactions
than MC participants high in extraversion, while individuals scoring high in extraversion in the PD group
had more intense panic-fear reactions than PD patients low in extraversion. None of the findings were
significant for neuroticism.
Introduction
A sizable number of studies have examined the ability of the CO2 challenge to elicit panic attacks
in Panic Disorder (PD) patients (e.g., Papp et al., 1997; Holt & Andrews, 1989). Evidence finds PD
patients to be particularly susceptible to an exaggerated fear response to CO2 (Gorman et al., 1990). But
not all PD patients panic in response to CO2 challenges, making it important to determine whether
individual differences play a role in differential responding. Theorists have proposed a relationship
between biological susceptibilities to affective states and specific personality traits (e.g., Depue, 1996),
providing a model to study differential physiological reactivity in PD patients.
Although two studies investigating the relationship between CO2 ventilatory reactivity and
personality found healthy extraverts to be more reactive than their introverted counterparts (Saunders,
Heilpern, & Rebuck, 1972; Shershow, King, & Robinson, 1973), more recent studies have found no
relationship between personality traits and CO2 responsivity in either PD patients or healthy controls (e.g.,
Perna et al., 1994). The present study examined the relationship between the specific traits of extraversion
and neuroticism and anxiogenic response to CO2 in both PD patients and matched controls (MC). This
report represents a secondary analysis of data originally reported by Beck, Ohtake, and Shipherd (1999).
Hypothesis 1:
Fearful responding, as measured by: (1) the average intensity of panic symptoms, (2) the number
of panic symptoms present, (3) the level of panic or fear, and (4) the number of catastrophic
cognitions, will be negatively correlated with extraversion, irrespective of membership in the PD
or MC group.
Hypothesis 2:
Fearful responding, as measured by: (1) the average intensity of panic symptoms, (2) the number
of panic symptoms present, (3) the level of panic or fear, and (4) the number of catastrophic
cognitions, will be positively correlated with neuroticism, irrespective of membership in the PD or
MC group.
Method
Participants
Two groups of participants were included in the present study: (1) 14 patients with a current
principal diagnosis of Panic Disorder (PD), and (2) 14 individuals free from psychiatric diagnosis
(Matched Control [MC]), matched to the PD sample on age, height, gender, ethnicity, and smoking status.
Individuals were selected for the PD group based on an administration of the Anxiety Disorders Interview
Schedule- IV (ADIS-IV; DiNardo, Brown, & Barlow, 1994). Individuals were excluded if they received a
principal diagnosis other than PD (PD group) or reported subclinical levels of PD (MC group). See Table
1 for demographics and clinical features respectively.
These participants were assessed using the NEO Personality Inventory-Revised (NEO-PI-R; Costa
& McCrae, 1992), in order to determine their scores on the extraversion and neuroticism dimensions.
Procedure
After the administration of the ADIS-IV, participants were scheduled for a second visit for the
CO2 challenge. The challenge was administered individually in a sound and light controlled laboratory.
Upon arrival, participants had a mask placed tightly but comfortably on their face, held in place with an
open-weave cap and velcro straps. After a 1-minute baseline, participants were administered three breaths
of 35% CO2 using single-blind administration. Participants were told in advance that this gas mixture may
induce bodily sensations but that these changes would be transient.
Following the three breaths of 35% CO2, participants were instructed to complete the Diagnostic
Symptom Questionnaire (DSQ; Sanderson, Rapee, & Barlow, 1989). This measure asks participants to rate
the presence and intensity of the 13 DSM-IV panic symptoms using a 9-point Likert scale and the presence
of catastrophic cognitions. From this measure we derived 4 scores: (1) the average intensity of panic
symptoms, (2) the number of panic symptoms present, (3) the level of panic or fear, and (4) the number of
catastrophic cognitions.
Results
Our hypotheses predicted that fearful responding would be negatively correlated with extraversion
and positively correlated with neuroticism, irrespective of PD or MC group status. However, different
patterns emerged in the correlations between extraversion and response to the challenge for the PD and
MC samples. As Table 3 shows, there were significant negative correlations between extraversion and the
number and intensity of panic symptoms, and catastrophic cognitions (p’s < .05) for the MC group. In
contrast, for the PD group, there were significant positive correlations between extraversion, both the
number and intensity of panic symptoms, and level of fear (p’s < .05). No significant relationships were
noted between neuroticism and any of the four response variables.
Discussion
Differential effects for the MC and PD groups were noted in the correlation between extraversion
and the four dimensions of anxious responding to CO2. Individuals scoring low in extraversion in the MC
group had more intense panic-fear reactions in response to the CO2 challenge than MC participants high in
extraversion. In contrast, PD patients scoring higher in extraversion had more intense panic-fear reactions
following the challenge than low extraversion PD participants. Perhaps the combination of the active,
excitability of high extraversion and the fear of physical sensations common to PD patients is correlated
with intense, dramatic panic-like reactions to the arousal associated with the CO2 challenge. Surprisingly,
neuroticism did not significantly relate to any measure of anxious reactivity to the CO2 challenge.
The findings of the present study are tempered by its small sample size. The results should be
interpreted cautiously and require replication. Although these results are preliminary, they are supportive
of an interface between personality and anxious responding to panic-provoking stimuli.
References
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Panic Disorder: A comparison of hypercapnic and hypoxic challenges. Journal of Abnormal Psychology,
108, 473-482.
Costa, P.T., Jr., & McCrae, R.R. (1992). Revised NEO Personality Inventory (NEO-PI-R) and
NEO Five-Factor Inventory (NEO-FFI) professional manual. Odessa, Fl: Psychological Assessment
Resources.
Depue, R.A. (1996). A neurobiological framework for the structure of personality and emotion:
Implications for personality disorders. In J.F. Clarkin & M.F. Lenzenweger (Ed.). Major theories of
personality disorder. New York: Guilford.
DiNardo, P., Brown, T, & Barlow, D. (1994). Anxiety Disorders Interview Schedule for DSM-IV.
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Holt, P., & Andrews, G. (1989). Hyperventilation and anxiety in panic disorder, agoraphobia, and
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Table 1
Description of Panic Disorder (PD) and Matched Control Participants
____________________________________________________________________________
PD (n = 14)
MC (n = 14)
Variable
M
SD
n
M
SD
n
p
____________________________________________________________________________
Age (years)
32.8
Education
14.7
Gender (% female)
85.7
Ethnicity (% Caucasian) 92.8
Height (inches)
64.7
Smoking status (% yes) 42.8
Duration of PD (years) 9.5
Severity of PD (0-8)
5.4
Severity of Agoraphobia (%)
None
7
Mild
36
Moderate
50
Severe
7
Secondary diagnoses (%)
Generalized anxiety
disorder
64
Major depressive
episode
Specific phobia
29
Social phobia
21
Obsessive-compulsive
disorder
7
Anxiety disorder NOS 7
8.50
2.23
32.0
16.4
85.7
92.8
64.6
42.8
12
13
3.87
6
8.05
1.91
12
13
3.43
6
ns
ns
ns
ns
ns
ns
7.74
1.22
1
5
7
1
9
36
5
4
3
1
1
__________________________________________________________________________
Extraversion
50.0
74.4
.05
(26.6)
(25.1)
Neuroticism
88.4
18.6
.01
(12.7)
(19.2)
____________________________________________________________________________
Table 2
Correlations between personality and panic sensations and cognitions
in both Panic Disorder (PD) Patients and Matched Control (MC) Participants
____________________________________________________________________________
Average intensity
Number of
Level of
Catastrophic
of panic symptoms
panic symptoms panic or fear cognitions
____________________________________________________________________________
Extraversion
PD group
.62*
.54*
.53*
.39
MC group
-.62*
-.71**
-.41
-.69**
Neuroticism
PD group
-.43
-.25
-.19
-.12
MC group
.35
.47
.25
.38
____________________________________________________________________________
Note. ** = p <.01
* = p <.05