Behm. Res. Thu. Vol. 28. No. 6, pp. 469479.

0005-7967,90

1990

PANIC

ATTACKS

163.00 + 0.00

Copyright 0 1990 Pergamon Press plc

Printed in Great Britain. All rights reserved

WITHOUT

MATT G. KUSHNER’

FEAR:

AN OVERVIEW*

and BERNARD D. BEDMAN*

‘Medical College of Pennsylvania at EPPI, 3200 Henry Avenue, Philadelphia, PA 19129 and ZDepartment of Psychiatry, University of Missouri-Columbia, Health Sciences Center, Columbia, MO 65201, U.S.A. (Received

16 Murch 1990)

Sunuuary-‘Non-fearful panic disorder’ (NFPD) is a condition that meets DSM III-R criteria for panic disorder but lacks a report of subjective fear or anxiety. Presenting the first comprehensive overview of this issue, the authors describe studies investigating a wide range of apparently overlapping phenomena including NFPD, ‘somatically expressed panic’, ‘non-cognitive panic’, ‘alexithymic panic’, ‘non-clinical panic’, and ‘masked anxiety’. The review shows that such conditions account for from 20 to 40% of the panic disorder found in various medical populations, and that this group resembles conventional panic disorder in cross-sectional comparisons. We emphasize that a ‘triple-response’ model of anxiety is consistent with our conclusion that NFPD should be conceptualized as a panic disorder subtype. Finally, we discuss unresolved issues regarding the construct and predictive diagnostic validity of NFPD.

INTRODUCTION

Background

Freud was among the first clinical theoreticians to provide detailed descriptions of panic anxiety. Suggesting that the ‘anxiety attack’ may or may not include the reported experience of fear, Freud (1884) noted that “the proportion in which the somatic symptoms are mixed in anxiety attacks varies to a remarkable degree, and that almost every accompanying symptom alone can constitute the attack just as well as can the anxiety itself”(pp. 80-81; quoted from Katon, Vitaliano, Russo, Cormier, Anderson & Jones, 1986). Later, Freud (1895/1940) made a similar observation when he wrote that “. . . the feeling of [an] anxiety [attack] may have linked to it a disturbance of one or more of the bodily functions. . . . He complains of ‘spasms of the heart’, difficulty breathing’. . . and such like; and in his description, the feeling of anxiety often recedes into the background” (p. 86; bracketed material added by the current authors). Freud’s observation that reports of panic anxiety need not necessarily include a cognitive fear component remains provocative yet today. For example, because the DSM III screens for the presence of attacks that involve intense ‘fear’ before a panic disorder diagnosis can be considered, individuals experiencing attacks in the absence of a report of fear are excluded from this diagnosis by definition. However, in the revised addition of DSM III (DSM III-R), the screening criterion for panic disorder requires attacks with discrete episodes of intense ‘fear’ or ‘discomfort’. The functional result of this change has been to broaden the range of individuals for whom the diagnosis of panic disorder applies by potentially including individuals who do not report the experience of intense subjective fear accompanying their panic attacks (‘non-fearful panic disorder’; NFPD). In spite of these nosological changes and their practical implications (above), the scientific basis upon whether or not it is most appropriate to consider NFPD as a valid panic phenomenon remains quite obscure. That is, although NFPD can technically be included under the DSM III-R criteria for panic disorder, the empirical evidence and theoretical/nosological issues surrounding NFPD as a clinical construct have yet to be comprehensively and critically evaluated in the scientific literature. Thus, the purpose of this paper is to review studies related to NFPD, and to discuss the nosological and theoretical implications of these data. Conceptual definition for NFPD. One complicating factor in our attempt to conduct a comprehensive review of the literature associated with NFPD, is that this general phenomenon

*This manuscript is based upon an unpublished report that the authors prepared at the invitation of the DSM IV Anxiety Disorders Task Force. 469

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has been studied and discussed in the context of a number of different labels and operations. Thus, we began by identifying a broad conceptual definition of NFPD, and then sought to include in the review any literature that is apparently relevant to that definition. In this regard, we conceptually define NFPD as a condition in which affected individuals experience discrete and acute periods, episodes, attacks or spells that meet (or clearly appear to meet) DSM III or DSM III-R panic disorder criteria (including number of symptoms, type of symptoms, and frequency of attacks), where all of the attacks associated with the current manifestation of the disorder do not include any cognitive panic symptoms (i.e. reported feelings of ‘fear’). We also review studies investigating phenomena that, although not clearly meeting this conceptual definition, do appear to highlight important aspects of NFPD. Source and organization of material reviewed. In addition to our own published and unpublished data relating to NFPD, we review studies describing panic phenomena that appear to be relevant to this issue including ‘masked anxiety’, ‘somatically expressed panic’, ‘alexithymic panic’, ‘nonclinical panic’, and ‘non-cognitive panic’. Also, because of the overlap in symptomatology between patients experiencing NFPD and those experiencing a subset of somatization symptoms, we survey literature addressing this relation (i.e. co-occurrence of panic and somatization, and empirically derived subtypes of somatization symptoms resembling NFPD). In a final section, we discuss theoretical and conceptual issues surrounding NFPD, interpretational issues surrounding estimates of the prevalence of NFPD, the relation of NFPD to conventionally defined panic disorder, and the limitations to this review. NFPD among cardiology patients. In a series of studies, Beitman and his colleagues have investigated cardiology patients with panic disorder but with no reported experience of fear during episodes (i.e. NFPD) (Beitman, Basha, Flaker, DeRosear, Mukerji & Lamberti, 1987; Beitman, Kushner, Lamberti & Mukerji, 1990). These researchers defined NFPD in the following way: (1) meets DSM III-R criteria for panic disorder except that; (2) their attacks involve discrete periods of intense ‘discomfort’ without ‘fear’; (3) their last ‘bad’ attack did not include symptoms that involve a subjective element of fear (i.e. fear of dying, going crazy or losing control). Utilizing a diagnostic structured interview, Beitman and his colleagues (1987) interviewed 104 cardiology patients with atypical or nonanginal chest pain in order to determine the prevalence of current panic disorder among this group. Of the 38 patients positive for current panic disorder, these researchers reported that 12 patients (3 1.6%) also met criteria for NFPD as described above. In an attempt to document descriptive differences between the NFPD and the remaining 26 panic patients who did report fear with their attacks, Beitman and his colleagues (1987) contrasted these two panic groups on study measures. Results of statistical comparisons between NFPD and other panic patients revealed a few significant differences. Although NFPD patients tended to be older than other panic patients (47.3 vs 42.3 yr), this measure and other between group demographic measures (i.e. gender, marital status and social class) were not significantly different. Group comparisons of clinical features also yielded few significant differences. Comparisons of NFPD patients to other panic patients showed that age of panic disorder onset, duration of panic disorder, number of panic attacks in the week preceding the interview, and the number of symptoms during the last major panic attack were similar for both groups. However, NFPD patients were significantly less likely than other panic patients to report a simple phobia, and there was a statistical trend toward the former group reporting a lifetime history of major depression less frequently than the latter group (P < 0.08). Finally, NFPD patients and other panic patients were compared on multiple dimensions of psychological symptomatology as assessed by a self-report questionnaire. Of the nine subscales of this instrument, significant group differences were noted on three (i.e. interpersonal sensitivity, depression, and psychoticism). In each case NFPD patients were less symptomatic than other panic disorder patients. In a reanalysis of the above data that involved 49 patients who cardiologists identified as having no evidence of coronary artery disease, Kushner and Beitman (1989) evaluated the relation of NFPD to agoraphobic avoidance and anticipatory anxiety. Because of the central role of cognitions in the development and/or maintenance of agoraphobia (e.g. Telch, Brouillard, Telch, Agras & Taylor, 1989) these authors hypothesized that NFPD patients should be less vulnerable to the

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development of agoraphobia. Results confirmed the major study predictions by showing that, as compared to panic patients reporting fear, NFPD patients reported significantly less inter-attack anticipatory anxiety and were significantly less likely to be rated as agoraphobic based upon the SCID interview. In order to address the concern that the results of the Beitman et af. (1987) study are ambiguous due to the possibility that cardiology patients were actually suffering with an undetected heart ailment rather than panic disorder, Beitmen et al. (1990) replicated that study in a sample of 94 cardiology patients who were angiographically free from coronary artery disease (i.e. ~30% stenosis). Similar to earlier findings, results showed that 13 (41%) of 32 patients meeting criteria for panic disorder also fit the NFPD criteria. Group comparisons showed few significant differences between the panic groups on demographic, clinical or diagnostic features. However, the low number of patients in this sample demonstrating agoraphobic avoidance precluded a replication of Kushner and Bietman (1989) described above. Somatically expressed panic disorder in primary care patients

Patients described as presenting to primary care physicians with panic disorder that is characterized by attacks of somatic panic symptoms would appear to describe a group similar to, if not identical with, those we have called NFPD patients. For example, Katon et al. (1986) administered the DIS interview to 195 primary care patients, but added four additional screening questions concerning core autonomic symptoms of panic disorder. If the patient responded negatively to the DIS screening question “Have you ever had a spell or attack when all of a sudden you felt frightened, anxious or very uneasy in situations when most people would not be afraid?‘, then the interviewer also asked the following panic screening questions: (1) Do you ever have sudden episodes of rapid heart beat or feeling like your heart is pounding loudly? (2) Do you ever have sudden episodes of lightheadedness or feeling faint? (3) Do you ever have sudden episodes of sweating, hot flushes or trembling? (4) Do you ever have sudden episodes of chest tightness or a feeling of smothering or not being able to get enough air to breathe? If the patient responded positively to either the standard DIS (‘fearful’) screening question or to any of the four additional (‘somatic’) screening questions, then the interviewer continued assessing for the presence of panic disorder. Using the standard fearful screening question, Katon et al. (1986) found that 26 patients (13.3%) were positive for current panic disorder and an additional 17 patients (8.7%) were experiencing panic attacks that were too infrequent to meet panic disorder criteria (‘simple panic’). Using the somatic screen questions, however, they identified an additional 5 patients with panic disorder (19.2% of those who were diagnosed using conventional criteria and 2.6% of the total sample) and an additional 8 patients with simple panic (47.1% of those who were diagnosed using conventional criteria and 4.1% of the total sample). Katon et al. (1986) provided several comparisons between panic patients identified by the standard DIS screening question and those identified by the additional somatic screening questions. Perhaps suggesting that somatic screening questions are not, in and of themselves, highly specific to panic disorder, they reported that although 65% of those identified with the conventional screen met full panic criteria, only 38% of those identified by the somatic screening questions met full panic criteria. They also reported that panic patients identified by the somatic screening questions did not differ from other panic patients on the Zung Anxiety Scale or the Somatization and Depression subscales of the SCL-90. However, the former were significantly less symptomatic than the latter on the Beck Depression Inventory along with the Phobic-Anxiety and Anxiety subscales of the SCL-90. Additionally, and consistent with Beitman et al. (1987) Katon et al. (1986) reported that those with panic disorder who were identified by the somatic screening questions had significantly fewer simple phobias than did other panic patients. Finally, they reported that the clinical importance of the patients identified by the somatic screening is buttressed by their finding that this group was significantly more symptomatic on all the measures described above when compared to those with no panic disorder.

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panic

Rachman, Lopatka and Levitt (1988) (also see Rachman, Levitt & Lopatka, 1987) serendipitously identified a group of individuals experiencing panic attacks in the absence of fearful cognitions (‘non-cognitive panic’). The method whereby these authors recorded cognitions went considerably beyond the inquiry into cognitive panic symptoms described by DSM III-R. Based upon a cognitive symptom checklist developed by Chambless (1985), they recorded the occurrence of cognitive fears surrounding passing out, acting foolish, having a heart attack, suffocating, losing control, screaming, panicking, choking, being paralyzed by fear, and running out of the room to breathe. Ss were said to have had a non-cognitive panic attack if, during a panic attack, they did not endorse any of the fearful cognitions listed on the checklist. In these studies Rachman et al. (1987, 1988) described the relation of cognitions and DSM III panic attack symptoms during 69 trials where 20 panic disorder patients were each exposed to several situations with the aim of inducing panic (only 30 trials resulted in a panic attack). Of relevance to the current discussion, they found that 8 (26.6%) of 30 panic attacks occurred in the absence of any fearful cognitions. Of note, of the approximately one-third of the total sample who reported at least one non-cognitive panic attacks, only 40% reported exclusively non-cognitive panics for each of the panic trials (15% of the total sample). Importantly then, it is only those who experienced exclusively non-cognitive panic attacks that would appear to meet our conceptual definition of NFPD.* In discussing these findings, Rachman and his colleagues provide several potential conceptualizations of non-cognitive panic. First, they suggest that these Ss may have actually had fearful cognitions that were not detected because they were not included in the study’s cognitive checklist. However, they also point out that this interpretation would appear to be unlikely as they had, in addition to the cognitive checklist, provided Ss with an open ended question regarding other cognitions they may have had during the panic trial. Second, they suggest that non-cognitive panickers may have had fearful cognitions that they were unable to detect, recall, or describe. Although it is difficult, if not impossible to test (i.e. disconfirm) this interpretation, the view that cognitions outside of the individual’s immediate awareness may be related to anxiety problems would appear to be consistent with the influential writings of Aaron Beck (1987) concerning ‘automatic thoughts’, and also fits with the ‘alexithymia’ viewpoint that suggests that these individuals are simply incapable of identifying and reporting their own emotional experiences. A final interpretation, that these patients may have become habituated to the panic experience over time, is intriguing and suggests the testable idea that prolonged exposure to panic attacks may lead to a lessening of fearful ideation surrounding that experience in some patients. If this were the case, however, it would remain to be explained why some patients seem to become sensitized to anxiety in the face of panic attacks with increasing frequency and duration. Case reports of NFPD-like

syndromes

In addition to the work reviewed above, several writers have described medical patients (e.g. GI, neurology) variously characterized as experiencing ‘masked anxiety’ and ‘alexithymic panic’ (Jones, 1984; Rosenbaum, 1987; Russell, Kushner, Beitman & Bartels, 1991). Although these case reports are less methodologically rigorous than those described above, we do not believe that they speak to the clinical face of validity of the NFPD construct. Alexithymic panic. Jones (1984) provided a case description of a patient who was presented with the physical findings of panic attacks, but without emotional complaint. He described this as a case of “alexithymic (literally, without words for feelings) panic”. According to this report, the patient, who was admitted to the hospital because of diabetic acidosis, developed chest pain, shortness of breath and rapid breathing resulting in an emergency (albeit negative) evaluation by hospital staff for myocardial infarction or pulmonary embolism. After other evaluations for a medical etiology of these symptoms were found to be negative, psychiatric consultation concluded that, although *Because Rachman ef al. (1987, 1988) specify that their Ss were diagnosed with DSM III panic disorder (which necessarily even those experiencing exclusively includes discrete episodes of fear or apprehension), it is unclear whether, non-cognitive panic attacks during the studies’ panic trials, did not experience some fearful panic attacks over the course of their disorder.

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denying any subjective depression or anxiety, the patient was apparently experiencing repeated panic attacks that involved typical symptoms such as chest pain, dyspnea, palpitations, dizziness, cold flushes, sweating and,trembling. The patient, however, insisted on a medical conceptualization

of his problem (i.e. low blood sugar), and left the hospital without treatment for the anxiety condition. Masked panic. A published report by Rosenbaum (1987) provides several case reports of apparent ‘masked panic’ presenting as either a cardiac, GI or neurological complaint. In each of these cases, the patients experienced their episodes as primarily somatic events, presented for treatment to medical clinics specializing in the bodily system in which they were experiencing their symptoms, and provided a long medical history involving a series of expensive and, in some cases, invasive diagnostic procedures that were negative. Based upon these cases, Rosenbaum (1987) outlines guidelines for aiding in the differential diagnosis of paroxysmal physical symptoms of uncertain etiology that include the following: (1) (2) (3) (4) (5) (6) (7)

Paroxysmal physical symptoms with persistent lower-grade symptoms. Onset with major life stress. Childhood history of symptoms: school avoidance, separation difficulties, excessive shyness. Partial relief with benzodiazepines. Lifetime history of depression. Family history of panic attacks or agoraphobia. Positive response to antipanic agents (p. 412).

NFPD in neurology patients confirmed by lactate infusion. Russell et al. (1991) provided a detailed report of three cases involving neurology patients with negative medical work-ups who were described as experiencing NFPD based upon a psychiatric consultation. In each case, extensive medical workups were conducted and found to be negative prior to the psychiatric evaluation. Of particular interest, all patients reported experiencing both a ‘typical episode’ in response to sodium lactate infusion, and also a positive treatment response to antipanic medications. One of these cases, for example, was a 31 yr old surgeon referred by his neurologist for a psychiatric evaluation because of attacks of near syncope which had been occurring for 6 months, chiefly at the beginning of difficult vascular operations. The patient had no prior psychiatric history and stated that he did not feel that he needed psychiatric consultation but admitted to increasing stress at work with the loss of his new partner approx. 10 months before this evaluation. The patient also admitted to having lost a patient in surgery for the first time in his career approx. 8 months prior to the evaluation and 1 month prior to the onset of his recurrent near syncopal episodes. He related a family history of depression and anxiety attacks in his mothyr. The patient, who described himself as a perfectionist, said that his father had died in surgery approx. 1 yr before the patient entered medical school. These episodes were described as feeling like “lights were going out”. He also felt like he was having difficulty breathing during that time and said that he began to sweat all over. He said that he did not experience anxiety during the episodes although he was beginning to feel worried when entering the operating room about having another attack and had cut back on his operating schedule. The patient denied symptoms of major depression, although he appeared mildly depressed at the time of the interview. The patient’s work up to that date had included a Holter monitor, negative coronary artery study, negative CAT scan, negative LP, negative MRI, and he also had negative thyroid functions B12, and folate. A double blind, placebo controlled sodium lactate infusion resulted in replication of his presenting symptoms. The patient was begun on imipramine at 75 mg hs and had relief of his symptoms on 150 mg hs total daily dose. At 6 months follow-up, the patient remained free of symptoms.

Note -clinical panic and NFPD Researchers investigating non-patients in community or student samples positive for a history of panic attacks (‘non-clinical panickers’) have found that these individuals typically report low levels of cognitive panic symptoms (e.g. Norton, Cairns, Wozney & Malon, 1988; Norton, Dorward & Cox et al., 1986; Rapee, Aneis & Barlow, 1988; Telch, Lucas & Nelson, 1989). For example, Norton et al. (1986) reported that of the 23% of their student sample who reported experiencing

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at least one panic attack (cued or uncued) in the 3 weeks prior to assessment, 37% denied experiencing DSM panic symptoms involving cognitive fears, with an additional 18% indicating ‘mild’ cognitive fear symptoms only. Similarly, Rapee et al. (1988) found that students who acknowledged a lifetime history of at least one uncued panic attack (14% of their student sample), reported significantly less cognitive anxiety accompanying somatic panic symptoms than did a group of panic patients sampled from an anxiety disorders clinic. Although a majority of non-clinical panickers do not experience panic attacks with the frequency required by the DSM for a diagnosis of panic disorder (e.g. only 2.4% reported by Telch et al., 1989), some evidence suggests that this difference, in and of itself, is inadequate to account for the low levels of cognitive fear in this group. For example, Norton et al. (1988) divided non-clinical panickers into ‘Infrequent Panickers’ (one or more panic attacks but none in the 3 weeks prior to testing), ‘Recent Panickers’ (one or two panic attacks in the 3 weeks prior to testing), and ‘Frequent Panickers’ (three or more panic attacks in the 3 weeks prior to testing) (15, 19 and 6% of the total sample respectively). Finding few group differences in the symptom severity ratings, measures of distress, and treatment seeking, these researchers concluded that panic frequency did not directly affect these important dimensions of the panic experience. With this said, however, additional research will be required before we can confidently assert the presence and nature of NFPD in non-clinical populations. Sornatkation and panic disorder symptomatology

Panic disorder has been shown to be highly associated with somatization phenomena. In 1986, Liskow and his associates showed that 44.9% of a sample of 78 female psychiatric outpatients with Briquet’s syndrome reported a lifetime of panic disorder and 87.2% reported a lifetime history of major depression. Orenstein (1989) reported similar results showing that of 16 psychiatric outpatients meeting strict diagnostic criteria for Briquet’s syndrome, 69% reported a lifetime history for panic disorder and 81% reported a lifetime history for major depression. Keyes, Reich, Clancy and O’Gorman (1986) reported that 60 patients with agoraphobia and panic disorder acknowledged levels of hypochondriacal symptomology similar to that of a group of hypochondriacal psychiatric outpatients. Of particular note in this study, after successful treatment for their panic, panic patients also reported significant reductions in their somatic preoccupation, disease phobia and disease conviction. These findings have led some researchers to speculate both that Briquet’s syndrome may represent an extreme expression of a tendency for syndromes such as panic disorder and depression to aggregate, and that somatization itself may represent a heterogeneous set of conditions. Evidence base upon the recent ECA community data base has provided some support for the view that DSM III somatization may actually describe a number of semi-independent symptom clusters, some of which appear to overlap substantially with those of NFPD. Swartz, Blazer, Woodbury, George and Landerman (1986; Swartz, Blazer, Woodbury, George & Manton, 1987) employed an innovative clustering procedure (‘grade of membership analysis’; GOM) to the DIS/DSM III somatization symptoms reported by respondents at one of the five ECA sites (only respondents endorsing three or more somatization symptoms were included). Of the seven ‘pure types’ this analysis uncovered, one resembled the traditional DSM somatization description with other pure types involving symptom clusters surrounding either menstrual symptoms, depressive symptoms, musculoskeletal complaints, gastrointestinal symptoms, or cardiac symptoms. The latter pure type. suggested by Swartz et al. to resemble neurocirculatory asthenia, included symptoms such as chest pain, shortness of breath, heart palpitations, fainting, dizziness, nervousness, blurred vision and food intolerance. Although not clear from this analysis, the 2.3% whose symptoms loaded substantially on the ‘cardiac type’ may include individuals who fit NFPD criteria. DISCUSSION Preralence

of NFPD and reference population

Our review suggests that the prevalence of NFPD in various medical populations with negative medical findings (i.e. primary care, cardiology and neurology) ranges from between 20 to 40% of those with panic disorder. Further, Rachman et al. (1987) reported that approx. 15% of their panic

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disorder sample reported attacks exclusively in the absence of cognitive fear symptoms across multiple panic trials (however, see footnote on p. 472). Thus, these findings would appear to suggest that NFPD is present in these groups in potentially substantial proportions. We also reviewed studies supporting the existence of NFPD-like syndromes in community samples; however, these reports are more ambiguous on this issue than those based on clinical samples. Non-clinical panickers (with prevalence estimates ranging from 9 to 35%) for instance, although demonstrably low on self-reports of anxiety accompanying their panic symptoms (and thus suggesting the presence of non-fearful panic attacks in this group), may not fit our conceptual definition of NFPD because of the infrequency of their attacks. Similarly, the community data showing that 2.3% of those with three or more somatization symptoms experienced a cluster of symptoms that overlap with NFPD (Swartz et al., 1986, 1987), although consistent with view that NFPD is present in the community, does not offer enough information to allow for a firm determination as to this groups diagnostic status. Of note, the data reviewed documenting nonfearful panic-like episodes are based primarily on populations outside of the mental health system (e.g. cardiology, primary care, neurology). The lack of data showing the presence of these patients among general psychiatric samples may suggest that NFPD is a phenomenon most likely to be found in patients outside of a psychiatric setting. Although it would be a logical error to consider an absence of relevant data as constituting negative findings, we believe that the lack of attention of NFPD by researchers and clinicians up to now may reflect the infrequent presentation of such patients to psychiatrists as compared to other professionals. This view would appear to be buttressed by the common sense notion that for individuals whose symptoms involve primarily unexplainable bodily symptoms (vs unexplainable fear), the tendency at present for treatment outside of psychiatry would make more sense. Finally, it may be, as has been observed by one of us (BDB), that even when NFPD patients do present to a psychiatric clinic, they are typically treated as somatizers rather than anxiety patients (distinguishing these groups is discussed further below). For instance, despite the addition of the DSM III-R screen criterion word ‘discomfort’, psychiatrists may continue to insist upon the self-report of anxiety before they will consider an anxiety disorder diagnosis as potentially relevant. Theoretical/conceptual

issues

A threoretical base for considering anxiety without a report of cognitive fear. Can episodes that include somatic and/or behavioral, but not cognitive anxiety symptoms be considered an anxiety phenomenon? This thorny question concerns the construct validity of NFPD as an anxiety disorder (discussed in greater detail below); however, it is first necessary to explicate the conceptual platform upon which this issue can be addressed. That is, even prior to demonstrations of the empirical relation of NFPD to the more traditional panic disorder category, it is first necessary to specify a view of anxiety that either is, or is not, capable of conceptualizing a given disturbance, in the absence of a report of subjective fear, as potentially representing an anxiety phenomenon. Most recently, it has become generally accepted by experimental psychopathologists and clinical theorists (cf. Tuma & Maser, 1985) that the data of anxiety are multi- rather than uni-referential (i.e. physiological, behavioral and verbal report; the ‘triple-response’ view of anxiety), and that data based upon the various components of anxiety intercorrelate to only a limited degree (Lang, 1964, 1968, 1978, 1985; Rachman & Hodgson, 1974). Rachman and Hodgson (1974) along with Hodgson and Rachman (1974), for example, describe concordance vs disconcordance as the degree to which the anxiety components are positively correlated at any particular point, and the related concepts of synchrony vs de-synchrony as referring to extent of positive correlation of the anxiety subsystems as they change over time (disconcordance and de-synchrony indicating less positive correlation among the subsystems). Inasmuch as this widely accepted, theoretically based, and empirically supported view of anxiety explicitly acknowledges, and has documented, the potential for de-synchrony and disconcordance among the various anxiety subsystems (e.g. Rachman & Hodgson, 1974), then conceptual problems surrounding the potential classification of NFPD as an anxiety disorder would appear to be theoretically resolved. Related to the view that subjective reports of anxiety and fear are just one of several channels in which anxiety may manifest, is the observation made by Rachman et al. (1988) suggesting that the absence of a self-report of anxiety during an anxiety episode cannot be taken as evidence that

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the patient is not subjectively fearful. This view is consistent with a number of observations including: (1) we ultimately cannot know what an individual is actually experiencing; (2) clinical lore and increasing empirical evidence (cf. Lang, 1985) suggesting that individuals are often poor witnesses to their own emotional experience (an extreme instance of this phenomenon being the alexithymic syndrome); (3) the potential motivations one might have for denying cognitive symptoms (e.g. stoicism, shame over having ‘mental’ vs ‘physical’ symptoms, and issues surrounding secondary gains associated with a ‘physical’ but not a ‘mental’ problem); and, (4) the increasingly well-documented observation that the way in which individuals construe and report the symptoms of highly similar syndromes can vary greatly along both idiosyncratic and cultural lines (e.g. Leventhal, Nerenz & Straus, 1982). Thus, the theoretical question of whether one can be said to have anxiety in the absence of a fearful feeling, may be better conceptualized as the more empirical question, for whom, and under what circumstances will anxiety symptoms be manifest in physiological or behavioral idiom, but not in a self-report idiom. NFPD as characterized by the absence of cognitive/self-report

anxiety

The hallmark of NFPD is the experience of panic attacks in a somatic and/or behavioral idiom, but not in a self-report/cognitive idiom (i.e. in the absence of a self-report of fear). Thus, at the level of symptomatology, NFPD is distinguished from the conventional presentation of panic disorder primarily by the absence of self-reported fear during panic attacks. Although this is a definition of omission rather than commission, the nature of the cognitive and affective phenomena that are associated with NFPD panic attacks is an issue of potential empirical and clinical interest. Unfortunately, we are aware of no data that directly address this question. With this said, however, our own clinical experience and limited data drawn from beyond that which is directly related to NFPD per se, may be relevant to this issue. From both a clinical and definitional standpoint, the predominant phenomenology of NFPD patients during panic attacks relates to the sudden onset of somatic panic symptoms in the absence of a report of fearful feelings. Our clinical experience suggests that, although ‘acute discomfort’ (i.e. DSM III-R screening criterion relevant to NFPD) does generally characterize the panic attacks described by NFPD patients, it is most typical for NFPD patients to describe the phenomenology of their attacks in terms of the specific somatic symptoms that they experience. For example, NFPD patients that we have identified in cardiology samples often present with a primary complaint that includes chest pain. Although we are unaware of any studies involving NFPD that evaluate this issue further, other investigations into the cognitive and affective components generally elicited by the episodic onset of intense discomfort and/or pain may be relevant to this question (e.g. Philips, 1989). NFPD:

a panic disorder subtype, natural variation, or a distinct diagnostic entity

Given the clinical significant frequency of individuals who would appear to fit the NFPD category, and a sound theoretical base from which to reasonably conceptualize NFPD as an anxiety phenomenon, the next logical set of questions concerns the empirical relation between NFPD and more conventional views of panic disorder. The most preliminary question is whether NFPD should be classified as panic disorder, or rather should be considered as a separate diagnostic entity. NFPD as panic disorder. The available literature, we believe, is most consistent with a view of NFPD classified as a panic disorder phenomenon. A consistent finding is that, with the possible exception of risk for agoraphobia (Kushner & Beitman, 1989) NFPD patients and other panic disorder patients appear to be qualitatively similar to one another in terms of their clinical profile. In the most thorough comparisons available (Beitman et al., 1987, 1990; Katon et al., 1986) similarities between these groups greatly outweighed the differences. Also providing qualified support for the diagnostic similarity of these groups, is the positive treatment response to known antipanic agents and lactate sensitivity noted for NFPD patients in case reports (Rosenbaum, 1987; Russell et al., 1991). Thus, although these data are, in and of themselves, inadequate to unambiguously validate NFPD as a panic disorder, they do appear to point most clearly toward this conclusion. Non-fearful panic attacks as a natural variation of the panic symptom complex. Consistent with the idea that NFPD should be considered under the heading of panic disorder, is the view that

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panic attacks occurring in the absence of a report of fear may represent a natural variation in the panic symptom complex. This view, while consistent with the diagnostic validity of NFPD as a panic disorder, also raises the question of whether some individuals experience both fearful and nonfearful panic episodes. That is, where we have conceptually defined NFPD as a condition in which individuals experience attacks without fear predominantly, we should also consider whether some individuals may fluctuate throughout the course of their disorder between both fearful and nonfearful panic attacks. In the only study bearing on this question that we are aware of, Rachman et al. (1987) found that for several panic trials, approx. 66% of their sample reported exclusively panic attacks with fear, 15% reported exclusively panic attacks without fear, and 20% reported both fearful and nonfearful panic attacks (however, see footnote on p. 472). Thus, while further investigation into this question is clearly necessary, it would appear that in addition to the NFPD phenomenon that we have discussed (exclusively non-fearful panic attacks), there may also be a group of individuals who experience both fearful and nonfearful panic attacks. Implications of NFPD for the diagnosis of panic disorder

Given our view that NFPD should be diagnostically identified with conventional panic disorder, the question still remains as to whether NFPD should be treated as a subtype of panic disorder; or, should this group simply fall, undistinguished, under the panic disorder heading? First, although not a robust or highly replicated finding, data reported by Katon et al. (1986), Beitman et al. (1987), and Kushner and Beitman (1989) appear to suggest that the NFPD patients tend to be somewhat less disturbed than other panic patients. Also, and perhaps of greater potential importance, are the data suggesting that it is medical specialists outside of the mental health system who may be most likely to contact NFPD patients. To the extent that this is a valid claim, then the importance of identifying NFPD as a subtype of panic disorder that is particularly likely to be encountered outside of the mental health system would appear to be indicated. Related to the above point, because NFPD patients may demonstrate distinct help-seeking patterns (above), and because these patients may not readily appear to the clinician (or to others) to be experiencing panic (i.e. lacking a self-report of anxiety), we believe that establishing this group as a clearly defined panic disorder subtype would aid in their accurate identification. That is, although current data have yet to clarify whether NFPD represents a group of patients that are meaningfully distinct from other panic patients, data we review do suggest that unless diagnosticians attend specifically to the non-fearful manifestation of panic disorder, such patients are unlikely to be questioned further concerning anxiety symptoms. Finally, we believe that a lack of attention to this issue in DSM III and III-R may have resulted in a general underestimation of the prevalence of panic disorder that will vary from population to population (above). It is possible, for example, that a subset of individuals who have previously been considered as somatizers (not necessarily meeting full criteria) may be better classified as NFPD patients (see above discussion of work by Swartz et al., 1986, 1987). Limitations to this review

There are a number of potentially relevant ‘gaps’ in this literature as it stands to-day. First is the lack of studies directly addressing the predictive and construct validity of NFPD. Concerning construct validity, we can assert with some confidence that: (1) anxiety can occur in the absence of a self-report of fear; (2) NFPD and other panic patients appear to be cross-sectionally similar to one another; (3) anecdotal and single case reports suggest that NFPD patients respond to sodium lactate infusion and to antipanic medications in a fashion that is similar to those with panic disorder that includes fear. However, these data do not unambiguously validate NFPD as a panic anxiety construct. In an attempt to address the construct validity of NFPD, we are currently conducting a family history study with NFPD patients, other panic patients, and controls. If, as we predict, the NFPD group shows comparable levels of psychopathology in their first degree relatives compared to other panic patients, then the construct validity of NFPD as a panic disorder phenomenon would be supported. Similarly, data addressing the predictive validity of NFPD (e.g. treatment response, longterm course) are currently inadequate. The case reports and anecdotal evidence showing that

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NFPD patients respond positively to antipanic medications are informative and useful but do not provide a sound methodological base from which we can confidently assert their conclusions. Thus, methodologically controlled research addressing the predictive validity of NFPD is lacking as of yet. A problem that is related to the discussion above is that most studies describing NFPD patients have utilized non-psychiatric samples. Although we suspect that this situation reflects both the relatively low occurrence along with misdiagnosis of NFPD patients in psychiatric settings, this viewpoint has not been empirically verified. In any case, our lack of knowledge about the nature and extent of NFPD in psychiatric settings is a clear limitation to the literature on this topic. Finally, before meaningful research can continue in this area, it will be necessary to establish uniform operational criteria for NFPD. Although we have referred to a number of different diagnostic operations as if they were synonymous with NFPD (e.g. non-cognitive panic, somatic panic, masked anxiety, alexithymic panic), this may be inappropriate. For example, Rachman et al. (1987) did not attend to the DSM panic symptoms endorsed by non-cognitive panic patients, but rather defined this group by an absence of endorsement of any cognitive symptoms during panic attacks on a separate self-report checklist. Also Katon et al. (1986) identified somatic panickers based upon their meeting full panic disorder criteria with the exception of denying any episodes of fear, but acknowledging episodes involving somatic symptoms. Beitman et al. (1987, 1990) requires an endorsement of a somatic screen question, denial of fear, and the absence of a report of fear of losing control or dying for patients’ last ‘bad’ attack. Clearly, the aim of meaningful research of NFPD would benefit by a uniform operation for this clinical construct. CONCLUSION To conclude, we have reviewed and discussed the available evidence bearing on NFPD. We believe that in questioning the common sense view that the cognitive/self-report idiom of anxiety is the sin que non of diagnostic validity, we can gain the opportunity to be more theoretically and clinically specific concerning the nature of panic and other manifestations of anxiety. Limitations to the current literature not withstanding, we believe that the view that NFPD is a diagnostically valid subgroup of classical panic disorder is currently justified. More specifically, the available literature concerning NFPD leads us to conclude the major points summarized below: (1) A triple-response view of anxiety provides a conceptual platform upon which to consider NFPD as a panic anxiety phenomenon. One particular advantage to this perspective being that the absence of a self-support of fear, does not conceptually imply that individuals are not feeling fearful. (2) To date, NFPD has been primarily documented in non-psychiatric, medical settings (accounting for 20-40% of those with panic disorder in these groups); however, due to an absence of data, the generalizability of these findings to patients seen in psychiatric settings is questionable. Similarly, although several reports suggest that NFPD may be present in the community to some degree, the data addressing this issue are currently inconclusive. (3) NFPD should be diagnostically identified as a panic disorder based upon data suggesting that: (a) NFPD patients appear to be highly similar to conventional panic patients in cross-sectional comparisons; (b) NFPD patients appears to be anti-panic medication responsive and lactate sensitive; and, (c) limited evidence suggesting that non-fearful panic attacks are a natural variation of the panic symptom complex. (4) NFPD should be designated as a subtype of panic disorder in order to maximise the likelihood that an anxiety disorder diagnosis will not be overlooked in this group. This would appear to be particularly relevant to the extent that NFPD patients are most likely to present to medical specialists outside of mental health (as our experience and limited data suggests that they are), and to the extent that diagnosticians are currently unwilling to consider an anxiety diagnosis in patients presenting without a self-report of fear. (5) Although we believe that the current literature is adequate to support an association between conventional panic disorder and NFPD, we also conclude that continued research into the construct and predictive validity of NFPD will be necessary before firm conclusions as to its diagnostic status can be drawn.

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