Pergamon

Behav. Res. Thu. Vol. 32, No. I, pp. 135-139, 1994 Copyright 0 1994 Else&x Science Ltd

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OVERPREDICTION OF FEAR IN PANIC DISORDER WITH AGORAPHOBIA

BRIAN J. Cox* and RICHARD P. SWINSON

Anxiety Disorders Clinic, Clarke Institute of Psychiatry, 250 College St, Toronto, Ontario, Canada M5T 1R8 and Department of Psychiatry, University of Toronto, Ontario, Canada

(Received 5 November 1993)

Summary-The overprediction of fear model is discussed in relation to the development and maintenance of panic disorder with agoraphobia. Data are presented which demonstrate a significant relationship between self-reports of phobic avoidance and anticipation of panic, both before and after treatment, and the occurrence of panic. Implications of the overprediction model for exposure-based therapy are also discussed along with its limitations and some directions for future research.

INTRODUCTION

Cognitive and behavioural models of panic attacks and panic disorder have stimulated an impressive amount of research in recent years, but noticeably less theoretical work has emerged on phobic fear and avoidance. Consistent with the orientation of the DSM-III-R (American Psychiatric Association, 1987), most of the work on panic disorder with agoraphobia (PDA) has focused on the panic aspect rather than the agoraphobic fear and avoidance behaviour.

One of the few exceptions to this trend is the overprediction of fear model proposed by Rachman (e.g. Rachman & Bichard, 1988). In this model, fearful individuals are seen as particularly prone to overestimate how much fear they will experience in a fear-provoking situation and this may maintain phobic avoidance. If a ‘mismatch’ between predicted and actual fear occurs where the fear has been overpredicted, there is a tendency for the actual reported fear to be reduced and this will eventually lead to reductions in predicted fear. Conversely, underpredictions of fear will lead to subsequent predictions upwards. When a correct ‘match’ is made between predicted and actual fear, there is no subsequent change in the level of predicted fear.

Rachman and Bichard (1988) reviewed evidence from experimental and clinical studies and the results generally supported the model. Compared to research on panic, however, there has not been a subsequent surge of research activity on this topic. The overprediction of fear model may have special relevance for understanding the development and maintenance of agoraphobia, including the role of panic in this condition, and possibly for improving exposure therapy for PDA.

Although many people tend to be ‘overpredictors’, repeated exposure to the feared stimulus usually results in decreases in reported fear and decreases in predicted fear (Rachman & Lopatka, 1986). Exposure therapy may be effective because of this tendency, based on results that repeated exposure to feared stimuli in overpredictors generally results in decreases in reported and predicted fear. However, many individuals with PDA might not engage in self-directed exposure and experience this naturally occurring fear reduction because of spontaneous, unexpected panic which can be viewed as a severe form of underprediction.

Rachman and Levitt (1985) observed that unexpected panic attacks in claustrophobic Ss resulted in subsequent increases in predicted fear, This pattern was also observed in 20 panic disorder patients (Rachman, Lopatka & Levitt, 1988). This tendency may explain part of the role of an unexpected spontaneous panic (underprediction) leading to individuals overpredicting panic in a wide variety of situations. If these overpredictors then tend to avoid situations where they overpredict a panic, they will never get a chance to realize they may have been overpredicting,

*Author for correspondence

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736 BRIAN J. Cox and RICHARD P. SWINSON

because there will be no subsequent or repeated exposure to the feared stimuli and agoraphobia will be maintained. As Rachman and Bichard (1988) have noted, these overpredictors may have fewer “opportunities for learning trials and disconfirmations” (p. 3 IO).

It could be argued that because of the spontaneous (non-situational nature) of this type of panic, there is no real overpredicting because there is no phobic stimulus or cue. The answer may be that what starts as a specific under-prediction may quickly spread to a pan-situational overprediction. In one study on variables associated with levels of agoraphobic severity, Cox (1993) found that the strongest determinant of severity of agoraphobic avoidance was the anticipation of panic on/y in relation to agoraphobic situations. The occurrence or anticipation of spontaneous panic was not a significant variable. Therefore, there is evidence to suggest that agoraphobia is maintained by a possible overprediction of fear (panic) in specific (agoraphobic) situations. Trait anxiety over novel, ambiguous situations was also associated with agoraphobic severity in the same study, suggesting that agoraphobics overpredict fear in new, unfamiliar situations.

Rachman et al. (1988) have shown that when mismatches of predicted/actual fear occur in panic disorder, they are significantly more likely to be of the overprediction type rather than underpre- diction. Similarly, Cox, Swinson, Norton and Kuch (1991) found that avoidance of specific situations in PDA was significantly associated with the anticipation of panic attacks but rarely with the occurrence of panic. We sought to replicate these findings in a second, larger sample of PDA patients and to examine the occurrence and anticipation of panic in relation to avoidance ratings following exposure-based treatment. Finally, implications of the overprediction model for behavioural treatment for PDA are discussed.

METHOD

Subjects

The sample in the first part of this study consisted of 73 PDA patients (21 males, 52 females) with a mean age of 33.14 yr (SD = 9.89). The sample in the second part of this study included 19 PDA patients (4 males, 15 females) with a mean age of 38.16 yr (SD = 13.81) who had completed behavioural group therapy. There were 10 sessions of group therapy, three of which involved therapist-aided in Vito exposure. All patients were diagnosed according to DSM-HI-R (APA, 1987) criteria by a psychiatrist or a clinical psychology doctoral student.

Materials and procedure

All patients completed the Fear Questionnaire (FQ; Marks & Mathews, 1979) and the Panic Attack Questionnaire (PAQ; Norton, Dorward & Cox, 1986) as part of their initial assessment. Patients who received behaviour therapy also completed a modified version of the FQ before and after treatment. The FQ was divided into separate fear and avoidance scales. The PAQ contains a section on situations in which panic attacks have occurred and how much individuals predict a future panic attack will occur (where 0 = never and 4 = very likely). All patients gave consent to using the info~ation for research purposes.

Table t. FQ situations and the occurrence and anticipation of panic attacks (N = 73)

Correlation Correlation between between

Reported FQ item FQ item and MCXn panic Anticipation of and pamc anticipation

FQ item rating SD occ”rrence (vu) panic occurrence of panic

Travel alone by bus or coach 3.89 2.79 72.6 2.71 0.32** 0.63** Walking alone in busy streets 3.18 2.71 56.2 2.1 I 0.48** 0.73** Going into crowded shops 3.29 2.38 75.3 2.30 0.42’1 0.69** Going aione fa from home 4.95 2.76 58.9 2.80 0.4x** 0.71** Large open spaces 2.12 2.72 35.6 1.40 0.57** 0.6X**

+*P <O.Ol. Note: occurrence and ~ntici~tion of panic are based on FQ items embedded in the Pamc Attack Questi~n~dire

Overprediction in FDA

Table 2. Pre- and post-treatment total FQ scores and the occurrence and anticipation of panic attacks (N = 19)

Correlation Correlation between between FQ-AG FQ-AG

Mean FQ and panic and anticipation rating SD occurrence of panic

FQ-AC (assessment) 21.58 9.03 0.17 0.55** Pre FQ-AG (fear) 24.32 8.90 0.39 0.57**

FQ-AG (avoid) 22.63 9.09 0.20 0.43’ Post FQ-AG (fear) 14.95 8.81 0.22 0.52**

FQ-AG (avoid) 12.95 7.70 0.13 0.43*

‘P < 0.10, *+p < 0.05.

RESULTS

Table 1 presents information on the relationship between agoraphobic situations avoided on the FQ, and the occurrence and anticipation of panic attacks (N = 73). Both the occurrence of panic and the anticipation of panic were significantly correlated with each of the 5 situations listed in the FQ agoraphobia subscale (FQ-Ag). An analysis of the size of the correlations indicated that, with the exception of the situation labelled ‘large open spaces’, the anticipation ratings had significantly higher correlations (P < 0.05) with agoraphobic avoidance than the occurrence ratings. The correlation between the total occurrence of panic rating and the FQ-Ag was 0.56 (P < 0.001) and the correlation between the total anticipation ratings and the FQ-Ag was 0.80 (P < 0.001). The sizes of these correlations were also significantly different (P < 0.01).

Table 2 presents the results for the sample of PDA patients who completed group behaviour therapy (N = 19). The total panic occurrence rating and total anticipation ratings were correlated with the FQ-Ag fear and avoidance ratings before and after treatment. The anticipation ratings were significantly correlated with almost all of the measures, while most of the panic occurrence correlations were of small size. The level of anxiety during exposure sessions was not recorded so patients who overpredicted, underpredicted, or matched their fear could not be identified, but prediction of fear (i.e. anticipation of panic) was significantly correlated with post-fear ratings.

DISCUSSION

The present results indicate that in most cases the anticipation of panic is more correlated with avoidance of specific situations than is the occurrence of panic in PDA, replicating earlier findings (Cox Ed al., 1991). In addition, fear and avoidance ratings of agoraphobic situations both before and after behaviour therapy were significantly correlated with the anticipation of panic, but not with the occurrence of panic. However, it should be noted that there is a possible measurement confound in that the occurrence of panic was coded as a categorical variable whereas the anticipation of panic was coded as a continuous variable; there is more possible variance in the latter case.

The level of actual reported fear during in uivo exposure was not recorded in the present study but the results do show a significant relationship between predicted fear (anticipation of panic) that was recorded before exposure and the fear and avoidance ratings recorded after treatment.

In a sample of panic disorder patients, Rachman ei al. (1988) found that expected panic attacks upon exposure to the phobic stimulus were still associated with subsequent decreases in the estimated probability of panicking in the next trial. Only unexpected panics (underprediction of fear) were not associated with subsequent declines in predicted fear. These results have implications for exposure therapy for PDA. The results to date appear to emphasize the need for repeated exposure trials, until the predicted fear is decreased. This will often not occur after the initial exposure but may occur after repeated trials.

One of the most significant implications of the overprediction model for exposure treatment is that agoraphobics should not be taken on exposure trials where they don’t expect a panic or significant anxiety when in fact there is a good chance they will, because the occurrence of an unexpected panic may result in subsequent increases in predicted fear. While it seems logical to approach situations in a gradual, hierarchical fashion, patients should be told to expect a lot of

738 BRIAN J. Cox and RICHARD P. SWINSON

anxiety, at least initially. Ideally, exposure tasks where individuals overpredict their fear (expected panic), but don’t actually have a panic attack would be of the greatest benefit. Even if an individual then has an expected panic attack during the initial exposure trial, research findings suggest that this is not likely to result in an increase in predicted fear. Further, if an individual continues with repeated exposure trials, he or she will probably not continue to have panic attacks in subsequent trials and this will lead to a decrease in predicted fear.

Another implication concerns relapse prevention strategies. Because underpredictions appear to be so powerful in increasing predicted fear, successfully treated PDA patients should still be informed that they will probably experience another panic attack at some point in the future. They should be advised to return to the situation where the panic attack occurred as soon as possible.

As an aside, the overpredi~tion model suggests that this phenomena may actually bias results against exposure therapy studies that use a behavioural approach test (BAT) as part of their entry criteria. Underpredictors would be more likely to meet entry criteria whereas overpredictors, who would possibly benefit the most from exposure therapy, may not have enough anxiety on the BAT to enter the study.

Limitations and directions for future research

Perhaps the greatest challenge this model faces is the need to identify overpredictors on an a priori rather than post hoc basis for exposure therapy. One of the first steps towards this goal will be to gather data on characteristics of overpredictors and underpredictors (identified after the initial exposure trial). For example, individuals with very high levels of anticipatory anxiety or apprehension may do well in exposure therapy if they are willing to enter situations. In addition to characteristics about the individual, there may be situational patterns related to mismatches as well. For example, does the availability of exits/escape result in individuals experiencing less anxiety than originally anticipated? It may even be preferable to recommend to individuals to escape the situation if their anxiety level becomes more than anticipated, rather than have an unexpected, full-blown panic attack, especially given the finding that escape behaviour does not necessarily strengthen agoraphobic fear and avoidance (Rachman, Craske, Tallman & Solyom, 1986). It is not yet known how to increase the probability of an overprediction mismatch occurring during exposure therapy.

Rachman and Bichard (1988) hypothesized that overpredictors may have a dispositional tendency to overpredict the chances of aversive events in general. If this hypothesis is supported, then it might be expected that cognitive therapy designed to address catastrophic cognitions would be a useful adjunct to exposure therapy, possibly even before the first exposure trial. Rachman and Bichard (I 988) have noted that highlighting the discrepancy between predicted and actual fear may also be useful in treatment.

Finally, it is not clear if the overprediction of fear generalizes to all types of situations or whether it is limited to the specific situational type where the anxiety occurred. If spontaneous or unexpected panic was the original ‘underprediction of fear’, there is a need to determine why it may then result in the anticipation of panic in several specific situations (e.g. travelling alone).

In summary, the overprediction of fear model may be a heuristic framework for the development and maintenance of agoraphobia and the role of unexpected panic. It has the potential of improving exposure-based behaviour therapy for this condition, particularly if overpredictors can be identified u priori through future research.

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Cox, B. J., Swinson, R. P., Norton, G. R. & Kuch, K. (1991). Anticipatory anxiety and avoidance in panic disorder with agoraphobia. Behaviour Research and Therapy, 29, 363-365.

Marks, I. M. & Mathews, A. M. (1979). Brief standard self-rating for phobic patients. Behuriour Research and Therupy, 17, 263-267.

Norton, G. R., Dorward, J. & Cox, 8. J. (1986). Factors associated with panic attacks in nonclinical subjects. Beharivr Therapy, 17, 239-252.

Overprediction in PDA 739

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