Cognitive Restructuring and Interoceptive Exposure in the Treatment of Panic Disorder: a Crossover Study

Behavioural and Cognitive Psychotherapy, 1998, 26, 115–131 Cambridge University Press. Printed in the United Kingdom

COGNITIVE RESTRUCTURING AND INTEROCEPTIVE EXPOSURE IN THE TREATMENT OF PANIC DISORDER: A CROSSOVER STUDY

Jeffrey E. Hecker

University of Maine, U.S.A.

Christine M. Fink

Maine Head Trauma Center, U.S.A.

Nancy D. Vogeltanz

University of North Dakota, U.S.A.

Geoffrey L. Thorpe and Sandra T. Sigmon

University of Maine, U.S.A.

Abstract. The relative efficacy of cognitive restructuring and interoceptive exposure procedures for the treatment of panic disorder, as well as the differential effects of the order of these interventions, was studied. Eighteen clients with panic disorder were seen for four sessions of exposure therapy and four sessions of cognitive therapy in a crossover design study. Half of the participants received exposure therapy followed by cognitive therapy and for half the order was reversed. There was a 1-month follow-up period between the two interventions and after the second intervention. Questionnaire measures and independent clinician ratings were used to assess outcome. Participants expected greater benefit from cognitive therapy, but tended to improve to a similar degree with either intervention. The order in which treatments were presented did not influence outcome. Participants tended to improve with the first intervention and maintain improvement across the follow-up periods and subsequent intervention. Several methodological limitations qualify the conclusions that can be drawn from this study. These limitations, as well as some conceptual and methodological challenges of con- ducting this type of research, are discussed. Keywords: Panic disorder, cognitive-behavior therapy, cognitive restructuring, exposure therapy, interoceptive exposure.

Reprint requests to Jeffrey E. Hecker, Department of Psychology, University of Maine, 5717 Corbett Hall, Orono, ME 04469, U.S.A.

 1998 British Association for Behavioural and Cognitive Psychotherapies 116 J. E. Hecker et al.

Introduction The 1980s witnessed the development of psychological treatments of panic disorder that directly target panic attacks and the anxiety associated with them. These treatments are based upon cognitive-behavioral principles (Barlow & Cerny, 1988; Hecker & Thorpe, 1992). Typically, treatment includes some combination of four components: education about the phenomena of panic and panic disorder which emphasizes the role of cognitive variables and learning experiences, a physiological control strategy (usually relaxation training or controlled breathing), cognitive restructuring, and exposure to internal and external panic cues. Case studies and uncontrolled clinical trials provided the first evidence for the efficacy of cognitive-behavioral treatment of panic disorder (Barlow et al., 1984; Clark, Salkovskis, & Chalkley, 1985; Gitlin et al., 1985). The late 1980s and early 1990s saw the publication of controlled studies of panic disorder treatment from clinical research centers in the United States and Europe (Beck, Sokol, Clark, Berchick, & Wright, 1992; Barlow, Craske, Cerny, & Klosko, 1989; Clark et al., 1994; Klosko, Barlow, Tassinari, & Cerny, 1990; Margraf, Barlow, Clark, & Telch, 1993; Ost, 1988; Ost & Westling, 1995). These studies consistently reported strong and clinically mean- ingful improvement in general anxiety, phobic avoidance, depression and panic attacks. Findings of 80% or more of panic disorder clients achieving panic-free status by the end of treatment were consistently reported. Follow-up studies indicate maintenance of improvement one to two years post-treatment (Clark, Salkovskis, Hackmann, & Gelder, 1991; Craske, Brown, & Barlow, 1991). Establishment of general treatment efficacy has led to questions about the relative contributions of components of cognitive-behavioral intervention. Two studies have compared relaxation training with cognitive therapy and exposure to panic cues alone or in combination. Barlow et al. (1989) found that while relaxation training, cognitive restructuring plus exposure to physiological panic cues, and a combination treatment were superior to a wait-list control on a variety of measures, the treatment conditions that included cognitive and exposure strategies led to significantly more panic-free clients post-treatment than relaxation training alone. This advantage for cognitive restructuring plus exposure was still evident at two-year follow-up (Craske et al., 1991). Beck, Stanley, Baldwin, Deagle, and Averill (1994) compared cognitive therapy to relaxation training in the treatment of panic disorder. The interventions were delivered without exposure instructions or practice in this study. Both treatments were moderately effective with no clear differences appearing. Three studies have compared cognitive therapy (Clark, 1986) and applied relaxation (Ost, 1987). The latter intervention involves mastering a rapid relaxation technique and utilizing relaxation while gradually exposing oneself to feared conditions. Clark et al. (1994) found cognitive therapy to be more effective than applied relaxation on questionnaire measures and panic frequency, while Ost & Westling (1995) did not find consistent differences between the two procedures. Arntz and van den Hout (1996) found a clear advantage for cognitive therapy over applied relaxation on the percentage of panic-free patients and questionnaire measures at post-treatment and one month follow-up. The two interventions were no different at six-months post-treatment on questionnaire measures, but an advantage for cognitive therapy was still present based upon percentage of panic free patients. Cognitive and exposure therapies for panic disorder 117

Three studies have compared cognitive restructuring to exposure-based treatment of panic disorder. Margraf and Schneider (1991) treated a group of German panic disorder clients in one of four conditions: ‘‘pure’’ cognitive therapy (no exposure to internal or external panic cues); ‘‘pure’’ exposure treatment (no reattribution of anxiety symptons); a combined cognitive and exposure therapy; and a wait-list control. Analy- sis of outcome measures including panic diaries, questionnaire measures, psycho- physiological monitoring, client and therapist ratings, and response to a panic- induction procedure indicated positive effects across the three treatment conditions with no improvement in the wait-list group. There were no outcome differences between the three treatment conditions, but fewer clients dropped out of the combined treatment condition. Bouchard et al. (1996) treated 28 individuals with panic disorder with agoraphobia over 14 sessions of exposure or cognitive restructuring. Exposure therapy was conducted in groups and involved exposure to interoceptive panic cues (e.g., voluntary hyper- ventilation, spinning) in sessions 1–7 and group discussion of individualized in vivo exposure exercises, practiced individually between sessions, in sessions 7–14. Cognitive restructuring was also conducted in groups and was based upon standard practitioner guides (Barlow & Cerny, 1988; Beck & Emery, 1985; Clark & Salkovskis, 1987). These researchers hypothesized that, while both interventions would be effective, exposure therapy would result in more rapid therapeutic gains. Results indicated no differences in rate of change and the interventions were equally effective. In a third study comparing cognitive therapy with an exposure treatment, Williams and Falbo (1996) treated 48 individuals with panic disorder. Many of their subjects also met criteria for other axis I disorders (i.e., 26 with social phobia, 25 with major depression). There were four treatment conditions: cognitive therapy (Barlow & Cerny, 1988; Beck & Emery, 1985); performance-based treatment (Williams, 1990; Williams & Zane, 1989); combined treatment; or delayed treatment control. In performance-based treatment, therapists assisted subjects in developing plans for approaching activities that tended to provoke panic attacks. Subjects would practice these activities for three hours each week between sessions. Therapists used a variety of guided mastery aids, as described by Williams (1990), to help subjects succeed at mastering challenging situations. No cognitive restructuring techniques were used. Results indicated that all three interventions were effective in helping subjects master panic. Performance-based treatment was signiﬁcantly superior to cognitive therapy on one measure of generalized phobic avoidance and two measures of panic-related cognitions. In summary, controlled trials have demonstrated cognitive-behavior therapy to be an effective treatment for panic disorder. Research to date on the components of cognitive-behavior therapy suggest that cognitive therapy by iteslf can be effective (Arntz & van den Hout, 1996; Margraf & Schneider, 1991; Salkovskis, Clark, & Hackmann, 1991) and may be more effective than relaxation training (Arntz & van den Hout, 1996; Clark et al., 1994), although ﬁndings are inconsistent (Beck et al., 1994; Ost & Westling, 1995). Three studies comparing cognitive therapy to an intervention based only on exposure have found no differences among the two treatments and their combination (Bouchard et al. 1996; Margraf & Schneider, 1991; Williams & Falbo, 1996). 118 J. E. Hecker et al.

The present paper describes a fourth comparison between an intervention focussed exclusively upon cognitive restructuring and a pure exposure treatment of panic disorder. However, the present study goes one step beyond the extant literature by examin- ing treatment order effects as well. Utilizing a crossover design we compared cognitive therapy to exposure therapy but also the combination of these two interventions delivered in different orders. While cognitive therapy has preceded exposure in previous research trials (e.g., Barlow et al., 1989), there are no empirical data upon which to base a choice of one order over the other. Whereas other studies compared components of cognitive-behavior therapy to their combination using between-groups designs (Barlow et al., 1989; Margraf & Schneider, 1991; Williams & Falbo, 1996), the within- subject component of the crossover design allows us to examine the impact of adding the second intervention with the same subject sample.

Method Participants Participants were self-referred or referred by physicians, mental health professionals, or community agencies to the Psychological Services Center, University of Maine. Rather broad inclusion criteria were used for participant selection in order to attain a sample representative of clinical practice. Participants met criteria for panic disorder (American Psychiatric Association, 1987) as their principal diagnosis. Beyond that, any client who was 18 years or older, was willing to proceed after the project had been explained, and whose personal physician sent a letter indicating there were no medical contra-indications to the client’s participation was accepted into the study. Participants who were taking anxiolytic medications were included. They were asked, however, not to make any changes in their medication use over the course of the study. Participants were on stable doses of medications for at least three weeks before acceptance into the study and seven weeks before treatment was initiated. Panic disorder diagnoses were established over the course of two interviews. All participants were initially interviewed by the ﬁrst or fourth author, both of whom are licensed psychologists with considerable clinical and research experience with anxious clients. If a diagnostic impression of panic disorder was formed, clients were referred for a structured interview using the Anxiety Disorders Interview Schedule – Revised (ADIS-R; DiNardo et al., 1988). Graduate students in clinical psychology conducted the ADIS-R interviews and arrived at a diagnostic formulation. ADIS-R results were reviewed by the ﬁrst author who independently determined that panic disorder was the principal diagnosis.

Design A crossover design for comparing two treatments was used (Thorpe, Hecker, Cavallaro, & Kulberg, 1987). Each client received eight sessions of treatment over approximately four months; four sessions were devoted to cognitive therapy (CT) and four to exposure therapy (EX). Two experimental groups were formed: one in which cognitive therapy preceded exposure therapy (CT͞EX) and one in which the sequence was reversed Cognitive and exposure therapies for panic disorder 119

(EX͞CT). Five assessments were made: (1) before treatment, (2) after the ﬁrst block of four treatment sessions, (3) after one month of no contact, (4) after the second block of four treatment sessions, and (5) after a ﬁnal one-month period of no contact.

Materials Standardized self-report inventories. Participants completed a battery of self-report questionnaires at each assessment point. From the Fear Questionnaire (FQ; Marks & Mathews, 1979), five scores were derived: agoraphobia avoidance (FQAG), social phobia avoidance (FQSO), blood͞injury avoidance (FQBI), ratings of anxiety͞depression symptoms (FQAD) and a 0–8 point global self-rating of phobic distress (FQGL). The Agoraphobic Cognitions Questionnaire (ACQ) and Body Sensations Questionnaire (BSQ) describe thoughts and physical sensations experienced by agoraphobics during episodes of severe anxiety (Chambless, Caputo, Bright, & Gallagher, 1984). Partici- pants rate the frequency of occurrence of these thoughts (ACQ) and the anxiety elicited by the physical sensations (BSQ), both on 5-point scales. Section 39 of the Agoraphobia Questionnaire (AQ39) lists 25 situations commonly feared or avoided by agoraphobics (Thorpe & Burns, 1983, pp. 152–153). Participants rated their level of fear and likeli- hood of avoiding these situations on a 0–5 point scale. Finally, the Trait scale of the State-Trait Anxiety Inventory (Trait; Spielberger, Gorsuch, & Lushene, 1970) was used to assess trait anxiety, and the Beck Depression Inventory (BDI; Beck, Ward, Mendel- son, Mock, & Erbaugh, 1961) was used to assess depressed mood. Structured interviews. Therapists conducted tape-recorded structured interviews at assessment points 1, 3 and 5. The questions were taken from the Anxiety Disorders Interview Schedule (DiNardo, O’Brien, Barlow, Waddell, & Blanchard, 1983) section on panic disorder. Clients were asked if they had experienced an unexpected panic attack and to rate how disturbed they were by the 13 symptons of a panic attack. In addition, questions based upon the anxiety͞depression scale of the Fear Questionnaire (Marks & Mathews, 1979) were asked. Finally, participants described their general level of disturbance and disability due to anxiety and panic. The audiotapes were later rated independently by a clinical psychologist familiar with panic disorder (the fifth author). The tapes were presented to the rater without identifying information and in random order, so that tapes of different clients and at different assessment sessions appeared randomly. In that way, the independent rater was unaware of which treatment, if any, a given client had received and whether the interview had been conducted at assessment point 1, 3, or 5. The independent rater rated the severity of each of the 13 panic attack symptoms on a 0–4 point scale; the degree to which clients were troubled by each of the five items of the anxiety͞depression scale from the Fear Questionnaire on a 0–8 point scale; and clients’ global degree of disability͞disturbance associated with anxiety and panic on a 0–8 point scale. Three scores were derived from these ratings: Panic Symptoms (PS-Rate) was the sum of the ratings of the panic symptoms; Anxiety͞Depression (A͞D-Rate) was the sum of the ratings for the items from the anxiety͞depression scale; and Global Disturbance (GL- Rate) was the independent rater’s rating of global anxiety and panic-related disability and disturbance. 120 J. E. Hecker et al.

Self-monitoring. Participants were provided with daily record forms on which they were to record their general anxiety and panic attacks throughout their involvement in the study. Unfortunately, inconsistencies in participants’ understanding of the task and large amounts of missing data raised serious concerns about the validity of these data. Clients who stopped having panic attacks tended to stop completing daily panic diaries. Some participants only completed diaries if they had a panic attack. Therefore, the self-monitoring data were uninterpretable and were excluded from data analyses.

Expected benefit. A 0–8 point rating scale of ‘‘expectancy of benefit’’ was completed by the clients after the rationale for each treatment procedure had been explained. The expectancy scale was completed in the first session of each intervention.

Procedure Participants were arbitrarily assigned to project therapists on the basis of their avail- ability at times convenient to the client. Each therapist saw the same number of clients in each condition, alternating the order of treatments, so that if the therapist’s last client was in the EX͞CT condition, the next one would be in CT͞EX and vice versa. The treatment condition for the ﬁrst client seen by each therapist was randomly determined.

Pre-treatment Participants met with their therapists twice after the structured interview and prior to the onset of treatment. In the ﬁrst session, the therapists conducted the tape-recorded structured clinical interview and obtained a detailed description of a personally mean- ingful fearful situation from each participant. Therapists constructed a personal fear scene from each of the participants’ description. In the second session, participants’ heart rate and self-report responses during imagery of six fear scenes – ﬁve standard and one personal – were recorded. The results of this imagery assessment will not be reported here.

Treatment Treatment manuals for the cognitive and exposure therapies were developed for this project (available from the ﬁrst author). The procedures were modiﬁed from Beck and Emery (1985) and Barlow and Cerny (1988) and are described in detail in Hecker and Thorpe (1992). All treatment sessions were one hour in length and scheduled at weekly intervals.

Cognitive therapy. The goals and procedures for each of the four sessions of cognitive therapy were as follows. In session one, clients were taught a model of understanding panic attacks emphasizing the cyclical relationship between thoughts and body sensations which forms the basis of the cognitive model of panic disorder (see Clark, 1986). Cognitive and exposure therapies for panic disorder 121

Therapists explained the rationale and procedures of cognitive therapy. Clients and therapists began to explore the clients’ specific panic-related thinking styles using recent panic attacks experienced by the client as examples. In session two, therapists reviewed the cognitive model and helped clients to identify and dispute irrational beliefs, unhelp- ful automatic thoughts, and catastrophic images associated with anxiety and panic. In session three, identification and disputation of irrational panic and anxiety-related thoughts continued. In addition, therapists helped clients to generate a list of coping self-statements to use in challenging situations or in response to early signs of panic. In session four, clients practiced using coping self-statements while discussing panic attacks they had experienced in the past, challenges they were likely to face in the coming month, or both. Exposure therapy. The goals and procedures for each of the four sessions of exposure therapy were as follows. In session one, clients were taught a model of understanding panic attacks that explains the phenomenon as a learned (i.e., classically conditioned) fear of normal physical sensations. Following from this model, the therapists provided a rationale for exposure therapy. One or two trials of exposure to physical sensations were carried out. For all participants, the first exposure exercise was voluntary hyper- ventilation (Clark et al., 1985). Sessions two through four followed the same format. Recent panic attacks were discussed in terms of conditioned fear of normal body sensations; the rationale for exposure therapy was reviewed; two to three trials of exposure to panic cues were carried out. Therapists utilized a wide variety of exercises to help participants create physical sensations associated with panic: voluntary hyperventil- ation, running in place, standing and sitting repeatedly, jumping jacks, head shaking, obstructed breathing (e.g., tissue over mouth and nose), imagery instructions and others. Therapists were encouraged to be creative in helping participants to generate sensations similar to those they experience during a panic attack or which they avoid out of fear of having a panic attack. For example, one participant consumed taco chips with cheese dip to induce a choking sensation. Therapists always engaged in the exposure exercises with the client. Regardless of the procedure used, exposure trials followed the same format. Two minutes of exposure exercise were followed by 5 minutes in which participants sat, eyes closed, and concentrated on physical sensations. Therapists and participants then discussed the exposure exercise and ways to make the experience more like a panic attack. Participants were generally encouraged to practice exposure exercises between sessions but were not given specific homework assignments.

Therapists Therapists were two clinical psychologists with research and clinical experience with anxiety disorders (first and fourth author) and two advanced graduate students in clinical psychology (second and third authors). The first author supervised the graduate student therapists each week that they worked with participants and consulted with the fourth author periodically as he worked with participants. The first author was the therapist for eight of the clients who finished the project. The third and fourth author each worked with four clients who completed the project and the second author worked with two. 122 J. E. Hecker et al.

Results Dropouts Thirty-three clients referred to the University of Maine Psychological Services Center over the course of the project met diagnostic criteria for panic disorder based upon initial screening interview and ADIS-R. Eleven clients (33%) dropped out of the project after the ADIS-R interview and before their ﬁrst treatment session. Two clients in the EX͞CT condition (18%) dropped out of the study. One client completed all four sessions of exposure therapy but did not return for assessment 3, and the other dropped out of treatment after one session of exposure therapy. Two clients in the CT͞EX condition (18%) dropped out of the study. One client completed all four sessions of cognitive therapy but did not return for assessment 3, and the other client dropped out of treatment after three sessions of cognitive therapy. Dropouts did not differ from treatment completers on any demographic variables, pre-treatment questionnaire scores, or symptom severity ratings from the ADIS-R (e.g., avoidance ratings). The ﬁndings reported below are for the 18 participants who completed both treatments and all assessments. There were missing data for several participants due to experimenter error and non-compliance. Missing data were not replaced by averages.

Treatment completers Treatment completers were 17 women and 1 man. Their mean age was 42.06 years (SDG12.81, range 22–62). All participants were caucasian. Eight participants received a primary diagnosis of panic disorder and 10 received a primary diagnosis of panic disorder with agoraphobia. Agoraphobic avoidance was rated as mild for 8 of the 10 agoraphobic participants and moderate for 2. Thirteen participants met criteria for at least one additional axis I diagnosis (six generalized anxiety disorder, four major depressive episode, and one each for simple phobia, post-traumatic stress disorder and hypochondriasis). Fifteen participants were taking anxiolytic medication at the time of diagnosis. The average number of months between clients’ ﬁrst panic attacks and entry into the study was 103.72, but there was considerable variability (SDG130.30, range 1–504 months). Client characteristics are summarized Table 1.

Pretreatment comparisons Participants in the two treatment conditions did not differ in age, months since first panic attack, ratio of panic disorder to panic disorder with agoraphobia diagnoses (four panic disorder, five panic disorder with agoraphobia in each group), severity of agoraphobic avoidance (four mild and one moderate in each condition), or frequency of additional axis I diagnosis (7͞9EX͞CT clients, 6͞9CT͞EX clients). The 1 male participant was in the CT͞EX condition. All 9 participants in the CT͞EX condition were taking anti-anxiety medication, whereas 6 of the 9 in the EX͞CT condition were on medication; chi square was not significant, X 2(1, NG18)G1.60, pH.20. The two Cognitive and exposure therapies for panic disorder 123

Table 1. Client characteristics

Other Month since Condition Sex Age Agoraphobia Medication Axis I ﬁrst panic EX͞CT F 24 No Alprazolam — 33 EX͞CT F 58 No Alprazolam MDE1 30 Desipramine EX͞CT F 45 Mild Alprazolam SP2 146 EX͞CT F 45 Mild — GAD3 132 EX͞CT F 29 No — PTSD4 1 EX͞CT F 55 No Buspirone HCL GAD 9 Alprazolam EX͞CT F 35 Mild Lorazepam — 2 EX͞CT F 41 Mild Imipramine MDE 156 Alprazolam EX͞CT F 39 Mod. — GAD 168 ¯ ¯ EX͞CT xG41.22 xG75.22 SDG11.12 SDG72.84 CT͞EX F 25 No Alprazolam GAD 9 Lorazepam CT͞EX F 32 Mild Imipramine MDE 24 CT͞EX F 62 Mild Diazepam — 8 CT͞EX F 61 No Phenobarbital GAD 504 CT͞EX F 46 No Diazepam Hypo5 228 CT͞EX F 56 Mod. Diazepam GAD 240 Imipramine CT͞EX F 22 Mild Alprazolam — 9 CT͞EX M 45 Mild Buspirone HCL MDE 156 CT͞EX F 37 No Imipramine — 12 Diazepam ¯ ¯ CT͞EX xG42.89 xG132.22 SDG14.95 SDG170.12

Notes: 1 Major depressive episode; 2 Simple phobia; 3 Generalized anxiety disorder; 4 Post- traumatic stress disorder; 5 hypochondriasis. treatment conditions did not differ ( pH.15) on questionnaire measures or independent ratings of taped interviews.

Expected benefit Clients’ expectancy of benefit ratings for each intervention were compared using a 2B2, mixed design, repeated measures analysis with order of treatment (EX͞CT vs. CT͞EX) as the between-subjects factor and participants’ expectancy of benefit rating for each intervention as the within-subjects factor. A significant within-subjects effect was found (F(2, 12)G7.595, pF.05) with nonsignificant between-subjects and interaction effects. Clients expected to receive greater benefit from cognitive therapy (mean ratingG6.21) 124 J. E. Hecker et al. than from exposure therapy (mean ratingG4.79) after the rationale for each intervention had been explained.

Outcome Exposure versus cognitive therapy. The crossover design allows for comparison between the two treatments by analyzing the data across assessments 1, 2, and 3. Repeated measures analysis of variance procedures were carried out for the questionnaire measures. Treatment (exposure therapy versus cognitive therapy) was the between-subjects factor and trials (assessments 1, 2, and 3) was the within-subjects factor. Treatment main effect and treatment by trials interaction were nonsignificant. Significant trials effects were found for all the questionnaire measures except FQSO and Trait (see Table 2). Planned comparisons for trials effects indicated that most of the improvement took place between assessments 1 and 2 (ACQ: F(1, 17)G7.608, pF.05; BSQ: F(1, 15)G 5.29, pF.05; FQAG: F(1, 13)G5.35, pF.05; FQBI: F(1, 13)G10.64, pF.01; FQAD: F(1, 12)G1.99, pF.05; AQ39: F(1, 17)G14.13, pF.02; BDI: F(1, 16) 13.52, pF.01). Participants showed nonsignificant changes between assessments 2 and 3 except on the FQAG which showed continued improvement F(1, 13)G11.64, pF.01). The exception to this pattern of results was on the FQGL. Participants showed nonsignificant improvement between assessments 1 and 2 (F(1, 12)G1.99, pH.15) and between assessments 2 and 3 (F(1, 12)G3.26, pH.05). A significant treatment by trials interaction was found on the FQGL (F(2, 22)G5.85, pF.01). The cognitive therapy group showed improvement over the three assessments (F(2, 10)G8.72, pF.01), with participants showing a significant decrease immediately post-treatment F(1, 5)G7.50, pF.05) and no change between assessments 2 and 3 (F(1, 5)G.29, pH.60). The exposure therapy group did not show significant change over the three assessment periods on this variable (F(2, 12)G.83, pH.40). Structured interview data were analyzed across two trials (assessments 1 and 3) with treatment as a between-subjects factor. Significant trials effects were found for all three dependent variables taken from the structured interviews (GL-Rate: F(1, 12)G13.36, pF.005; PS-Rate: F(1, 13)G12.23, pF.005; A͞D-Rate: F(1, 12)G7.57, pF.05). There were no significant treatment by trials interactions. Order of treatments. The crossover design allows for comparison between the two orders in which treatment components were presented by analyzing the data across assessments 1, 4, and 5. Repeated measures analysis of variance procedures were carried out for the questionnaire measures. Treatment order (EX͞CT versus CT͞EX) was the between-subjects factor and trials (assessments 1, 4, and 5) was the within-subjects factor. Significant trials effects were found for all the questionnaire measures except for the FQAD and Trait (see Table 3). There were no significant treatment order by trials interactions. Planned comparisons indicated that participants showed significant change in the positive direction between assessments 1 and 4 (ACQ: F(1, 13)G6.16, pF.05; BSQ: F(1, 14)G12.81, pF.01; FQAG: F(1, 11)G19.14, pF.001; FQSO: F(1, 11)G7.73, pF.05; FQBI: F(1, 11)G4.89, pF.05; FQGL: F(1, 10)G26.67, pF.001; AQ39: F(1, 14)G17.84, pF.001; BDI: F(1, 14)G7.96, pF.05). Nonsignificant differences were found for all questionnaire measures between assessments 4 and 5 with the Cognitive and exposure therapies for panic disorder 125

Table 2. Means, standard deviations, F-ratios and p-values for trials effects on questionnaire measures across assessments 1, 2 and 3

Assessment Ե Measure 1 2 3 F(df ) pF ACQ 34.67 30.56 28.61 6.24 (2.32) .01 (11.13) (10.54) (9.93) BSQ 37.11 30.56 32.50 3.61 (2.28) .05 (16.86) (11.59) (11.64) FQAG 14.17 10.72 6.53 9.42 (2.24) .01 (9.09) (9.69) (6.56) FQSQ 13.58 10.94 9.40 1.78 (2.24) .20 (7.90) (6.63) (6.08) FQBI 14.71 10.83 10.60 5.49 (2.24) .01 (9.09) (8.30) (7.63) FQGL 3.94 3.56 3.27 3.89 (2.24) .05 (2.21) (1.92) (1. 87) FQAD 18.94 13.67 11.80 5.74 (2.22) .01 (9.96) (7.63) (5.80) AQ39 54.50 45.72 42.94 10.81 (2.32) .001 (21.08) (16.63) (17.00) BDI 14.94 9.44 11.17 7.68 (2.30) .005 (7.50) (6.45) (5.68) TRAIT 53.35 51.19 44.47 2.94 (2.24) .10 exception of the FQAG (F(1, 11)G6.39, pF.05) and the FQSO (F(1, 11)G8.80, pF.05) on which participants showed deterioration between assessments 4 and 5. On the FQAG, the mean score for participants at assessment 5 was still significantly lower than at assessment 1 (F(1, 11)G8.29, pF.05). On the FQSO, the difference between participants’ scores at assessments 1 and 5 was not statistically significant (F(1, 11)G 0.90, pH.30). Structured interview data were analyzed across two trials (assessments 1 and 5) with treatment order as a between-subjects factor. Significant trials effects were found for all three dependent variables taken from the structured interviews (GL-Rate: F(1, 9)G 61.36, pF.001; PS-Rate: F(1, 13)G18.89, pF.001; A͞D-Rate: F(1, 10)G5.14, pF.05). There were no significant treatment by trials interactions.

Clinical signiﬁcance. The percentage of participants to achieve an essentially nonpathological level of functioning was examined from three perspectives: (1) An independent judge – the independent clinician’s rating of global disturbance (GD-Rate) of 2 or less; (2) The client – self-rating of global disturbance from the Fear Questionnaire (FQGL) of 2 or less; and (3) Normative comparison – client’s scores on the measures of catastrophic thinking about anxiety (ACQ) and fear of bodily sensations (BSQ) both within one standard deviation of a normal sample (Chambless et al., 1984). The percentage of participants to meet criteria for clinically signiﬁcant outcome from each perspective at assessments 3 and 5 are presented in Table 4. Chi square analyses revealed no between group differences. 126 J. E. Hecker et al.

Table 3. Means, standard deviations, F-ratios and p-values for trials effects on questionnaire measures across assessments 1, 4 and 5

Assessment Ե Measure 1 2 3 F(df ) pF ACQ 34.67 28.94 27.00 4.48 (2.24) .05 (11.13) (11.44) (7.64) BSQ 37.11 30.76 31.60 5.81 (2.26) .01 (16.86) (12.18) (11.62) FQAG 14.17 5.46 7.93 12.32 (2.20) .01 (9.09) (6.46) (6.68) FQSQ 13.58 6.64 9.27 3.81 (2.20) .05 (7.90) (4.31) (5.67) FQBI 14.71 8.57 9.87 3.72 (2.20) .05 (9.09) (5.36) (5.08) FQGL 3.94 2.92 3.38 4.83 (2.18) .05 (2.21) (2.34) (1.77) FQAD 18.94 13.07 12.85 2.66 (2.18) .10 (9.96) (10.21) (8.19) AQ39 54.50 41.27 40.13 11.17 (2.28) .001 (21.08) (17.37) (13.43) BDI 14.94 10.18 10.00 5.65 (2.22) .01 (7.50) (6.15) (6.40) TRAIT 53.35 47.41 48.40 2.89 (2.24) .10 (10.79) (11.28) (8.83)

Table 4. Percentage of participants meeting criteria for clinically signiﬁcant outcome from three perspectives at assessments 3 and 5

Assessment 3 Assessment 5 Self Judge Norm Self Judge Norm EX͞CT 3͞92͞94͞94͞62͞84͞8 33% 22% 44% 67% 25% 50% CT͞EX 5͞83͞94͞92͞72͞65͞7 56% 33% 44% 29% 33% 71% All subjects 8͞17 5͞18 8͞18 6͞13 4͞14 9͞15 47% 28% 44% 46% 28% 60%

Discussion Both interoceptive exposure and cognitive restructuring as applied in here led to improvement in measures of psychopathology associated with the diagnosis of panic disorder. Participants showed statistically signiﬁcant improvement on measures of catastrophic thinking, fear of physical sensations associated with anxiety and panic, phobic avoidance, and depression. There was only one signiﬁcant difference between the two interventions. An advantage for cognitive therapy over exposure therapy was found on one variable: participants’ ratings of global disturbance (FQGL). Cognitive and exposure therapies for panic disorder 127

Methodological limitations There are several methodological limitations to the present study which need to be highlighted to assure that the findings are interpreted appropriately. (1) Small sample size. The small sample size (nine per condition) made it difficult to detect differences between the two interventions. Following procedures recommended by Keppel (1991), we conducted post-hoc power analyses on the primary dependent measures. Statistical power was in the range of 0.20 to 0.30 for the condition by trials interactions. With power this low the probability of a type two error is, of course, high. Kazdin and Bass (1989) have pointed out that the problem of insufficient statistical power to detect differences between two active psychotherapies is common. (2) Similarity between interventions. The problem of small sample size is exacerbated by the similarity between the two interventions studied. Both interventions provided subjects with information about panic disorder and models for understanding the development and maintenance of the problem. In addition, while we strove to maintain the purity of the two interventions, it is important to note that our study compared two sets of treatment procedures and not necessarily two theoretically distinct mechanisms of actions. In cognitive therapy, for example, discussion of past panic attacks might be considered a form of exposure therapy. Similarly, the classical conditioning model of panic disorder may have provided participants with an alternative attributional frame- work from which they could view physiological arousal associated with exposure exercises. The distinction between treatment procedure and mechanism of action is nicely illustrated when non-cognitive interventions result in greater changes on cognitive measures than do cognitive restructuring procedures (e.g., Williams & Falbo, 1996). Having struggled to implement pure cognitive and pure behavioral interventions, we have serious questions about the feasibility of this exercise. For an intervention to be purely cognitive, one would need to prohibit patients from engaging in any form of exposure. The intervention would then be extremely artificial and very different from cognitive restructuring as practiced. To do exposure therapy without imparting any information to patients about the purpose of the exercises would seem bizarre. Could one obtain a patient’s informed consent to participate in such an intervention without providing some rationale? The simple fact that patients are told that they are receiving treatment when asked to do exposure exercises imparts important information. (3) Generalizability of findings. We set out to examine the components of cognitive- behavioral treatment of panic disorder. However, the cognitive restructuring and interoceptive exposure procedures we examined were not identical to those used in the two most extensively studied cognitive-behavior therapy packages for panic disorder: Barlow’s Panic Control Therapy (Barlow & Cerny, 1988; Barlow & Craske, 1989) and Oxford University Cognitive Therapy Package (Clark, 1989; Salkovskis & Clark, 1991). For example, although generally encouraged to apply what they learned in therapy sessions, participants in our study were not given explicit assignments to practice exposure or cognitive exercises at home. Between-session homework assignments are used extensively in both the Cognitive Therapy and Panic Control Therapy packages. There- fore, while the interventions described in the current paper were similar to those used in these established packages, the study should not be seen as a direct test of their components. 128 J. E. Hecker et al.

(4) No direct measure of panic. The absence of a direct measure of panic frequency makes it difficult to compare our findings to other published studies and to assess the impact of the treatments on panic per se. It has become common practice to report the percentage of panic-free clients and some reviewers have used this as a convenient method of comparing findings across studies (e.g., Clark, 1996). (5) Drop-out rate: The relatively high drop-out rate raises concerns about the representativeness of our sample. It should be kept in mind, however, that the majority of drop-outs (11 out of 15 or 73%) quit the study before they were assigned to a treatment condition. There was a relatively lengthy pre-treatment assessment period (four or five meetings over as many weeks) which may have contributed to the drop- out rate. We could find no differences between participants who dropped out and treatment completers based upon pre-treatment assessment data. Therefore, we believe that the treatment completers are representative of the people referred to our clinic. Eighteen percent (4 out of 22) of the participants dropped out after some experience with the treatments. This drop-out rate is comparable to other studies in this area (e.g., Barlow et al., 1989; Beck et al., 1994). Bearing in mind these limitations, there was evidence that the two interventions were moderately successful at helping participants achieve a nonpathological level of functioning. Depending on the perspective from which clinically significant outcome was assessed, approximately one quarter to one half of the participants met criteria for nonpathological functioning. These findings are not as strong as published findings of full packages of cognitive and behavioral treatments of panic disorder (e.g., Barlow et al., 1989; Clark et al., 1994). The order in which the two interventions were delivered did not consistently influence outcome. Statistical analyses revealed no differences in participants’ functioning associated with the order in which treatments were delivered. In general, participants appeared to make gains over the course of the first treatment they received and maintained these gains over subsequent assessments. Very few subjects moved into the nonpathological range on the measures of clinical significance between assessment 3 and 5. Our findings are generally consistent with previous studies comparing cognitive and exposure therapies (Bouchard et al., 1996; Margraf & Schneider, 1991; Williams & Falbo, 1996). Cognitive therapy and exposure therapy are helpful for panic disorder when delivered alone. No strong advantage for one treatment over the other or for a combined intervention has been found. Our findings are also not inconsistent with those reported by Bouman and Visser (1994) in a series of studies in which cognitive and behavioral intervention were tested alone and in combination in treating hypochondriasis, a condition related to panic disorder (Salkovskis & Warwick, 1986). These researchers found that their versions of cognitive therapy and behavior therapy (i.e., exposure and response prevention) did not differ in terms of effectiveness in the treatment of hypochondriasis. However, the very low statistical power in that study does not allow for firm conclusions. Participants tended to expect greater benefit from cognitive therapy than interoceptive exposure after the rationale for each intervention was explained to them. This finding might argue for doing cognitive restructuring before beginning exposure exercises so that clients will begin therapy with a more optimistic attitude about treatment. Cognitive and exposure therapies for panic disorder 129

In the present study, however, attitude about treatment did not impact treatment drop- out rates and was not strongly associated with outcome. Higher expectancy of benefit ratings may account for the advantage seen for cognitive restructuring on clients’ global rating of disturbance. Our study provides additional evidence of the efficacy of cognitive-behavioral treatment. Furthermore, our findings indicate that panic disorder clients can be helped with relatively few treatment sessions. Craske, Maidenberg, and Bystritsky (1994) have recently reported similarly positive findings with a four session treatment which included several components of cognitive behavior therapy for panic disorder. We have also found cognitive behavior therapy involving minimal therapist contact (four brief meetings) to be as effective as the same intervention delivered in weekly psychotherapy sessions (Hecker, Losee, Fritzler, & Fink, 1996).

Acknowledgements The authors thank Melodie Greene, Peter Ippoliti, Tom Kivler, Melinda Losee, Jefferson Parker, and Melinda Smith for their contributions to various aspects of data collection, scoring, and analyses.

References

AMERICAN PSYCHIATRIC ASSOCIATION (1987). Diagnostic and statistical manual of mental disorders (3rd edn. – revised). Washington, DC: Author. ARNTZ, A., & VAN DEN HOUT, M. (1996). Psychological treatment of panic disorder without agoraphobia: Cognitive therapy versus applied relaxation. Behaviour Research and Therapy, 34, 113–121. BARLOW, D. H., & CERNY, J. A. (1988). Psychological treatment of panic. New York: Guilford. BARLOW, D. H., COHEN, A. S., WADDELL, M., VERMILYEA, J. A., KLOSKO, J. S., BLANCHARD, E. B., & DI NARDO, P. A. (1984). Panic and generalized anxiety disorder: Nature and treatment. Behavior Therapy, 15, 431–449. BARLOW, D. H., & CRASKE, M. G. (1989). Mastery of your anxiety and panic. Albany, NY: Greywind. BARLOW, D. H., CRASKE, M. G., CERNY,J.A.,&KLOSKO, J. S. (1989). Behavioral treatment of panic disorder. Behavior Therapy, 20, 261–282. BECK,A.T.,&EMERY, G. (1985). Anxiety disorders and phobias: A cognitive perspective, New York: Basic Books. BECK, A. T., SOKOL, L., CLARK, D. A., BERCHICK, R., & WRIGHT, F. (1992). A crossover study of focused cognitive therapy for panic disorder. American Journal of Psychiatry, 149, 778–783. BECK, J. G., STANLEY, M. A., BALDWIN, L. E., DEAGLE,E.A.,&AVERILL, P. M. (1994). Comparison of cognitive therapy and relaxation training for panic disorder. Journal of Con- sulting and Clinical Psychology, 62, 818–826. BECK, A. T., WARD, C. H., MENDELSON, M., MOCK, J., & ERBAUGH, J. (1961). An inventory for measuring depression. Archives of General Psychiatry, 4, 561–571. BOUCHARD, S., GAUTHIER, J., BABERGE, B., FRENCH, D., PELLETIER,M.H.,&GODBOUT, C. (1996). Exposure versus cognitive restructuring in the treatment of panic disorder with agoraphobia. Behavior Research and Therapy, 34, 213–224. 130 J. E. Hecker et al.

BOUMAN,T.K.,&VISSER, S. (1994, November). Empirical and clinical challenges in the cognitive behavioural treatment of hypochondriasis. Paper presented at the 28th Annual Meeting of the Association for the Advancement of Behavior Therapy, San Diego, CA. CHAMBLESS, D. L., CAPUTO, G. C., BRIGHT,P.,&GALLAGHER, R. (1984). Measurement of fear of fear in agoraphobics: The Body Sensations Questionnaire and the Agoraphobic Cog- nitions Questionnaire. Journal of Consulting and Clinical Psychology, 52, 1090–1097. CLARK, D. M. (1986). A cognitive approach to panic. Behaviour Research and Therapy, 24, 461– 470. CLARK, D. M. (1989). Anxiety states: Panic and generalized anxiety. In K. Hawton, P. Salkovskis, J. Kirk, & D. M. Clark (Eds.), Cognitive behaviour therapy for psychiatric prob- lems: A practical guide. Oxford: Oxford University Press. CLARK, D. M. (1996). Panic disorder: From theory to therapy. In P. M. Salkovskis (Ed.), Frontiers of cognitive therapy. New York: Guilford. CLARK,D.M.,&SALKOVSKIS, P. M. (1987). Cognitive treatment for panic attacks: Therapist’s manual. Oxford: Warneford Hospital. CLARK, D. M., SALKOVSKIS, P. M., & CHALKLEY, A. J. (1985). Respiratory control as a treatment for panic attacks. Journal of Behavior Therapy and Experimental Psychiatry, 16, 23–30. CLARK, D. M., SALKOVSKIS, P. M., HACKMANN,A.,&GELDER, M. (1991, November). Long- term outcome of cognitive therapy for panic disorder. Paper presented at the 25th Annual Meeting of the Association for the Advancement of Behavior Therapy, New York. CLARK, D. M., SALKOVSKIS, P. M., HACKMANN, A., MIDDLETON, H., ANASTASIADES, P., & GELDER, M. (1994). A comparison of cognitive therapy, applied relaxation, and imipramine in the treatment of panic disorder. British Journal of Psychiatry, 164, 759–769. CRASKE, M. G., BROWN,T.A.,&BARLOW, D. H. (1991). Behavioral treatment of panic disorder: A two-year follow-up. Behavior Therapy, 22, 289–304. CRASKE, M. G., MAIDENBERG, E., & BYSTRITSKY, A. (1994, November). Brief cognitive- behavioral treatment of panic. Paper presented at the 28th Annual Convention of the Associ- ation for the Advancement of Behavior Therapy, San Diego, CA. DINARDO, P. A., BARLOW, D. H., CERNY, J., VERMILYEA, B. B., VERMILYEA, J. A., HIMALDI, W., & WADDELL, M. (1988). Anxiety Disorders Interview Schedule – Revised (ADIS-R). Albany, NY: Phobia and Anxiety Disorder Clinic, State University of New York at Albany. DINARDO, P. A., O′BRIEN, G. T., BARLOW, D. H., WADDELL,M.T.,&BLANCHARD,E.B. (1983). Anxiety Disorders Interview Schedule (ADIS). Albany, NY: Phobia and Anxiety Dis- order Clinic, State University of New York at Albany. GITLIN, B., MARTIN, M., SHEAR, K., FRANCES, A., BALL,G.,&JOSEPHSON, S. (1985). Behavior therapy for panic disorder. Journal of Nervous and Mental Disease, 173, 742–743. HECKER, J. E., LOSEE, M. C., FRITZLER,B.K.,&FINK, C. M. (1996). Self-directed versus therapist-directed cognitive behavioral treatment of panic disorder. Journal of Anxiety Dis- orders, 10, 253–265. HECKER, J. E., & THORPE, G. L. (1992). Agoraphobia and panic: A guide to psychological treatment. Boston, MA: Allyn and Bacon. KAZDIN,A.E.,&BASS, D. (1989). Power to detect differences between alternative treatments in comparative psychotherapy outcome research. Journal of Consulting and Clinical Psychology, 57, 138–147. KEPPEL, G. (1991). Design and analysis: A researcher’s handbook (3rd Edn.). Englewood Cliffs, NJ: Prentice Hall. KLOSKO, J. S., BARLOW, D. H., TASSINARI, R., & CERNY, J. A. (1990). A comparison of alprazolam and behavior therapy in treatment of panic disorder. Journal of Consulting and Clinical Psychology, 58, 77–84. Cognitive and exposure therapies for panic disorder 131

MARGRAF, J., BARLOW, D. H., CLARK,D.M.,&TELCH, M. J. (1993). Psychological treatment of panic: Work in progress on outcome, active ingredients, and follow-up. Behaviour Research and Therapy, 31, 1–8. MARGRAF,J.,&SCHNEIDER, S. (1991, November). Outcome and active ingredients of cognitive- behavioral treatments for panic disorder. Paper presented at the 25th Annual Meeting of the Association for the Advancement of Behavior Therapy, New York. MARKS,I.M.,&MATHEWS, A. M. (1979). Brief standard self-rating for phobic patients. Behav- iour Research and Therapy, 17, 262–267. OST, L. G. (1987). Applied relaxation: Description of a coping technique and review of controlled studies. Behaviour Research and Therapy, 25, 397–409. OST, L. G. (1988). Applied relaxation in the treatment of panic disorder. Behaviour Research and Therapy, 26, 13–22. OST,L.G.,&WESTLING, B. E. (1995). Applied relaxation training vs. cognitive therapy in the treatment of panic disorder. Behaviour Research and Therapy, 33, 145–158. SALKOVSKIS,P.M.,&CLARK, D. M. (1991). Cognitive therapy for panic disorder. Journal of Cognitive Psychotherapy, 5, 215–226. SALKOVSKIS, P. M., CLARK, D. M., & HACKMANN, A. (1991). Treatment of panic attacks using cognitive therapy without exposure or breathing retraining. Behaviour Research and Therapy, 29, 91–94. SALKOVSKIS,P.M.,&WARWICK, H. M. C. (1986). Morbid preoccupation, health anxiety and reassurance: A cognitive-behavioural approach to hypochondriasis. Behaviour Research and Therapy, 24, 91–94. SPIELBERGER, C. D., GORSUCH,R.L.,&LUSHENE, R. E. (1970). Manual for the State-Trait Anxiety Inventory. Palo Alto, CA: Consulting Psychologists Press. THORPE,G.L.&BURNS, L. E. (1983). The agoraphobic syndrome: Behavioural approaches to evaluation and treatment. Chichester, UK: Wiley. THORPE, G. L., HECKER, J. E., CAVALLARO,L.A.,&KULBERG, G. E. (1987). Insight versus rehearsal in cognitive-behavior therapy: A crossover study with sixteen phobics. Behavioural Psychotherapy, 15, 319–336. WILLIAMS, S. L. (1990). Guided mastery treatment of agoraphobia: Beyond stimulus exposure. Progress in Behavior Modiﬁcation, 26, 89–121. WILLIAMS, S. L., & FALBO, J. (1996). Cognitive and performance-based treatments for panic attacks in people with varying degrees of agoraphobic disability. Behaviour Research and Therapy, 34, 253–264. WILLIAMS,S.L.,&ZANE, G. (1989). Guided mastery and stimulus exposure treatments for severe performance anxiety in agoraphobics. Behaviour Research and Therapy, 27, 237–245.