The symptom structure of panic attacks

Biobehavioral approach to distinguishing panic symptoms from medical illness

Panic disorder is a common psychiatric diagnosis characterized by acute, distressing somatic symptoms that mimic medically-relevant symptoms. As a result, individuals with panic disorder overutilize personal and healthcare resources in an attempt to diagnose and treat physical symptoms that are often medically benign. A biobehavioral perspective on these symptoms is needed that integrates psychological and medical knowledge to avoid costly treatments and prolonged suffering. This narrative review examines six common somatic symptoms of panic attacks (non-cardiac chest pain, palpitations, dyspnea, dizziness, abdominal distress, and paresthesia), identified in the literature as the most severe, prevalent, or critical for differential diagnosis in somatic illness, including long COVID. We review somatic illnesses that are commonly comorbid or produce panic-like symptoms, their relevant risk factors, characteristics that assist in distinguishing them from panic, and treatment approaches that are typical for these conditions. Additionally, this review discusses key factors, including cultural considerations, to assist healthcare professionals in differentiating benign from medically relevant symptoms in panic sufferers.

Chronic Serotonergic Overstimulation Mimicking Panic Attacks in a Patient with Parkinson's Disease Receiving Additional Antidepressant Treatment with Moclobemide

Background

The pharmacological treatment options of Parkinson's disease (PD) have considerably evolved during the last decades. However, therapeutic regimes are complicated due to individual differences in disease progression as well as the occurrence of complex nonmotor impairments such as mood and anxiety disorders. Antidepressants in particular are commonly prescribed for the treatment of depressive symptoms and anxiety in PD. Case Presentation. In this case report, we describe a case of a 62-year-old female patient with PD and history of depressive symptoms for which she had been treated with moclobemide concurrent with anti-Parkinson medications pramipexole, rasagiline, and L-DOPA+benserazide retard. An increase in the dosage of moclobemide 12 months prior to admission progressively led to serotonergic overstimulation and psychovegetative exacerbations mimicking the clinical picture of an anxiety spectrum disorder. After moclobemide and rasagiline were discontinued based on the hypothesis of serotonergic overstimulation, the patient's psychovegetative symptoms subsided.

Conclusions

The specific pharmacological regime in this case probably caused drug-drug interactions resulting in a plethora of psychovegetative symptoms. Likely due to the delayed onset of adverse effects, physicians had difficulties in determining the pharmacologically induced serotonin toxicity. This case report emphasizes the complexity of pharmacological treatments and the importance of drug-drug interaction awareness in the treatment of PD patients with complicating nonmotor dysfunctions such as depression.

Efficacy of mobile app-based interactive cognitive behavioral therapy using a chatbot for panic disorder

BACKGROUND

Cognitive behavioral therapy (CBT) is a well-established treatment for panic disorder, but many fewer patients receive this treatment compared to medication-based therapy. Mobile app-based interactive CBT using a chatbot can increase patient access to CBT. We performed a preliminary study to determine whether short-term use of a newly developed chatbot is feasible and effective for relieving panic symptoms.

METHOD

Forty-one patients were randomly assigned to either a chatbot group (n = 21) or control group (n = 20) for a period of 4 weeks. The chatbot group was guided in the use of the chatbot application, while the control group was provided with a book on panic disorder.

MAIN RESULTS

The severity of panic disorder was significantly decreased in the chatbot group, but not in the control group. The social phobia score was significantly decreased and the control helplessness score was significantly increased in the chatbot group compared to the control group.

DISCUSSION AND CONCLUSION

We found that mobile app-based interactive CBT using the chatbot was feasible and effective for reducing the severity of panic symptoms. Using this novel approach to provide CBT would allow clinicians to effect positive therapeutic outcomes with easy accessibility, interactivity, and self-management for patients with panic symptoms.

Panic disorder respiratory subtype: psychopathology and challenge tests - an update

Panic disorder (PD) pathophysiology is very heterogeneous, and the discrimination of distinct subtypes could be very useful. A subtype based on respiratory symptoms is known to constitute a specific subgroup. However, evidence to support the respiratory subtype (RS) as a distinct subgroup of PD with a well-defined phenotype remains controversial. Studies have focused on characterization of the RS based on symptoms and response to CO2. In this line, we described clinical and biological aspects focused on symptomatology and CO2 challenge tests in PD RS. The main symptoms that characterize RS are dyspnea (shortness of breath) and a choking sensation. Moreover, patients with the RS tended to be more responsive to CO2 challenge tests, which triggered more panic attacks in this subgroup. Future studies should focus on discriminating respiratory-related clusters and exploring psychophysiological and neuroimaging outcomes in order to provide robust evidence to confirm RS as a distinct subtype of PD.

Differences in anxiety sensitivity factors between anxiety and depressive disorders

BACKGROUND

Anxiety sensitivity (AS) refers to the tendency to fear physical sensations associated with anxiety due to concerns about potential physical, social, or cognitive consequences. Many previous studies were limited by the use of the anxiety sensitivity index (ASI) or the ASI-revised (ASI-R), which are both measurements with unitary or unstable structures. No recent study that has utilized the ASI-3 examined the relations between AS dimensions and depression. Thus, we examined multiple relationships between AS and anxiety disorders and depression using the ASI-3.

METHODS

The total sample consisted of 667 outpatients, diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders fourth text revision as assessed by a structured clinical interview. There were eight patient groups: multiple anxiety disorder, major depressive disorder (MDD), panic disorder (PD), social phobia (SP), obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), and anxiety disorder not otherwise specified (AD NOS). We conducted one-way analysis of variances and post hoc tests to compare the ASI-3 total and subscale scores across the groups.

RESULTS

The physical concern score was higher in patients with PD than patients with MDD, SP, OCD, or GAD. The social concern score was higher in the SP group than those with MDD, PD, GAD, and AD NOS. Patients with GAD and PTSD showed higher cognitive concern scores than the patients with PD.

CONCLUSION

Results partially replicated the relationship between PD and physical concern, between SP and social concern, and between GAD and cognitive concern examining the relationships between AS dimensions and anxiety disorders.

Dysfunctional beliefs in patients with obsessive-compulsive disorder and depression as assessed with the Beliefs Questionnaire (BQ)

There is an ongoing debate about the specificity of dysfunctional beliefs in patients with obsessive-compulsive disorder (OCD) as some of these beliefs seem to be relevant in depressed patients as well. The present study aimed to elucidate the specificity of dysfunctional beliefs using the newly developed Beliefs Questionnaire (BQ). A combination of an online assessment and clinical interviews was carried out. One hundred thirty OCD patients (M = 38.7 years; 68% women) were compared to 85 patients with depression (M = 36.6 years; 75% women) and 220 nonclinical controls (M = 38.9 years; 71% women) on the BQ, which contains 13 items tapping cognitive beliefs. The BQ was validated against the Obsessive Beliefs Questionnaire (OBQ). Patients with OCD and depression scored higher on the BQ compared to nonclinical controls. OCD patients displayed higher values on overestimation of threat and the fear of becoming insane. Correlation between BQ and OBQ total scores was high (r = 0.751), supporting the validity of the new scale. Our results show that two beliefs are OCD-specific. However, the BQ covers mainly transdiagnostic features and should be replicated with the inclusion of an anxiety disorder sample.

Select panicogenic drugs and stimuli induce consistent increases in tail skin flushes and decreases in core body temperature

Panic attacks (PAs) are episodes of intense fear or discomfort that are accompanied by a variety of both psychological and somatic symptoms. Panic induction in preclinical models (e.g. rats) has largely been assayed through flight and avoidance behavioral tests and cardiorespiratory activity. Yet, the literature pertaining to PAs shows that thermal sensations (hot flushes/heat sensations and chills) are also a common symptom during PAs in humans. Considering that temperature alterations are objectively measurable in rodents, we hypothesized that select panicogenic drugs and stimuli induce consistent changes in thermoregulation related to hot flushes and chills. Specifically, we challenged male rats with intraperitoneal injections of the GABAergic inverse agonist FG-7142; the α2 adrenoceptor antagonist yohimbine; the serotonin agonist D-fenfluramine, and 20% CO2 (an interoceptive homeostatic challenge). We assayed core body temperature and tail skin temperature using implanted radiotelemetry probes and tail thermistors/thermal imaging camera, respectively, and found that all challenges elicited rapid, high-amplitude (~7-9°C) increase in tail skin temperature and delayed decreases (~1-3°C) in core body temperature. We propose that thermal sensations such as these may be an additional indicator of a panic response in rodents and humans, as these panicogenic compounds or stimuli are known to precipitate PAs in persons with panic disorder.

Panic Disorder Comorbidity with Medical Conditions and Treatment Implications

Panic disorder (PD) is unique among the anxiety disorders in that panic symptoms are primarily of a physical nature. Consequently, comorbidity with medical illness is significant. This review examines the association between PD and medical illness. We identify shared pathophysiological and psychological correlates and illustrate how physiological activation in panic sufferers underlies their symptom experience in the context of the fight-or-flight response and beyond a situation-specific response pattern. We then review evidence for bodily symptom perception accuracy in PD. Prevalence of comorbidity for PD and medical illness is presented, with a focus on respiratory and cardiovascular illness, irritable bowel syndrome, and diabetes, followed by an outline for potential pathways of a bidirectional association. We conclude by illustrating commonalities in mediating mechanistic pathways and moderating risk factors across medical illnesses, and we discuss implications for diagnosis and treatment of both types of conditions.

Subregional Shape Alterations in the Amygdala in Patients with Panic Disorder

BACKGROUND

The amygdala has been known to play a pivotal role in mediating fear-related responses including panic attacks. Given the functionally distinct role of the amygdalar subregions, morphometric measurements of the amygdala may point to the pathophysiological mechanisms underlying panic disorder. The current study aimed to determine the global and local morphometric alterations of the amygdala related to panic disorder.

METHODS

Volumetric and surface-based morphometric approach to high-resolution three-dimensional T1-weighted images was used to examine the structural variations of the amygdala, with respect to extent and location, in 23 patients with panic disorder and 31 matched healthy individuals.

RESULTS

There were no significant differences in bilateral amygdalar volumes between patients with panic disorder and healthy individuals despite a trend-level right amygdalar volume reduction related to panic disorder (right, β = -0.23, p = 0.09, Cohen's d = 0.51; left, β = -0.18, p = 0.19, Cohen's d = 0.45). Amygdalar subregions were localized into three groups including the superficial, centromedial, and laterobasal groups based on the cytoarchitectonically defined probability map. Surface-based morphometric analysis revealed shape alterations in the laterobasal and centromedial groups of the right amygdala in patients with panic disorder (false discovery rate corrected p < 0.05).

CONCLUSIONS

The current findings suggest that subregion-specific shape alterations in the right amygdala may be involved in the development and maintenance of panic disorder, which may be attributed to the cause or effects of amygdalar hyperactivation.

Dimensional structure of bodily panic attack symptoms and their specific connections to panic cognitions, anxiety sensitivity and claustrophobic fears

BACKGROUND

Previous studies of the dimensional structure of panic attack symptoms have mostly identified a respiratory and a vestibular/mixed somatic dimension. Evidence for additional dimensions such as a cardiac dimension and the allocation of several of the panic attack symptom criteria is less consistent. Clarifying the dimensional structure of the panic attack symptoms should help to specify the relationship of potential risk factors like anxiety sensitivity and fear of suffocation to the experience of panic attacks and the development of panic disorder.

METHOD

In an outpatient multicentre study 350 panic patients with agoraphobia rated the intensity of each of the ten DSM-IV bodily symptoms during a typical panic attack. The factor structure of these data was investigated with nonlinear confirmatory factor analysis (CFA). The identified bodily symptom dimensions were related to panic cognitions, anxiety sensitivity and fear of suffocation by means of nonlinear structural equation modelling (SEM).

RESULTS

CFA indicated a respiratory, a vestibular/mixed somatic and a cardiac dimension of the bodily symptom criteria. These three factors were differentially associated with specific panic cognitions, different anxiety sensitivity facets and suffocation fear.

CONCLUSIONS

Taking into account the dimensional structure of panic attack symptoms may help to increase the specificity of the associations between the experience of panic attack symptoms and various panic related constructs.

Etiology, triggers and neurochemical circuits associated with unexpected, expected, and laboratory-induced panic attacks

Panic disorder (PD) is a severe anxiety disorder that is characterized by recurrent panic attacks (PA), which can be unexpected (uPA, i.e., no clear identifiable trigger) or expected (ePA). Panic typically involves an abrupt feeling of catastrophic fear or distress accompanied by physiological symptoms such as palpitations, racing heart, thermal sensations, and sweating. Recurrent uPA and ePA can also lead to agoraphobia, where subjects with PD avoid situations that were associated with PA. Here we will review recent developments in our understanding of PD, which includes discussions on: symptoms and signs associated with uPA and ePAs; Diagnosis of PD and the new DSM-V; biological etiology such as heritability and gene×environment and gene×hormonal development interactions; comparisons between laboratory and naturally occurring uPAs and ePAs; neurochemical systems that are associated with clinical PAs (e.g. gene associations; targets for triggering or treating PAs), adaptive fear and panic response concepts in the context of new NIH RDoc approach; and finally strengths and weaknesses of translational animal models of adaptive and pathological panic states.

Panic symptom clusters differentially predict suicide ideation and attempt

Increasingly strong evidence links anxiety disorders in general and panic attacks in particular to suicidality. The underlying causes and specifics of this relation, however, remain unclear. The present article sought to begin addressing this question by clarifying the association between panic symptoms and suicidality. Data were sampled from the NESARC epidemiological data set from the US and analyzed as four independently, randomly selected subsets of 1000 individuals using structural equation modeling analyses and replicating results across samples. Evidence is presented for four symptom clusters (cognitive symptoms, respiratory distress, symptoms of alpha and beta adrenergic activation) and the differential association of each with suicidal ideation and attempts. Symptoms of alpha adrenergic activation predicted prior suicide attempt whereas cognitive symptoms predicted prior suicidal ideation. These findings were independent of comorbid major depressive disorder. It is suggested that assessment of suicide risk in the community includes the presentation of cognitive symptoms and symptoms related to alpha adrenergic activation.

Recurrent spontaneous attacks of dizziness

PURPOSE OF REVIEW

This article describes the common causes of recurrent vertigo and dizziness that can be diagnosed largely on the basis of history.

RECENT FINDINGS

Ninety percent of spontaneous recurrent vertigo and dizziness can be explained by six disorders: (1) Ménière disease is characterized by vertigo attacks, lasting 20 minutes to several hours, with concomitant hearing loss, tinnitus, and aural fullness. Aural symptoms become permanent during the course of the disease. (2) Attacks of vestibular migraine may last anywhere from minutes to days. Most patients have a previous history of migraine headaches, and many experience migraine symptoms during the attack. (3) Vertebrobasilar TIAs affect older adults with vascular risk factors. Most attacks last less than 1 hour and are accompanied by other symptoms from the posterior circulation territory. (4) Vestibular paroxysmia is caused by vascular compression of the eighth cranial nerve. It manifests itself with brief attacks of vertigo that recur many times per day, sometimes with concomitant cochlear symptoms. (5) Orthostatic hypotension causes brief episodes of dizziness lasting seconds to a few minutes after standing up and is relieved by sitting or lying down. In older adults, it may be accompanied by supine hypertension. (6) Panic attacks usually last minutes, occur in specific situations, and are accompanied by choking, palpitations, tremor, heat, and anxiety. Less common causes of spontaneous recurrent vertigo and dizziness include perilymph fistula, superior canal dehiscence, autoimmune inner ear disease, otosclerosis, cardiac arrhythmia, and medication side effects.

SUMMARY

Neurologists need to venture into otolaryngology, internal medicine, and psychiatry to master the differential diagnosis of recurrent dizziness.

The development of agoraphobia is associated with the symptoms and location of a patient's first panic attack

Background

The place where a patient experiences his/her first panic attack (FPA) may be related to their agoraphobia later in life. However, no investigations have been done into the clinical features according to the place where the FPA was experienced. In particular, there is an absence of detailed research examining patients who experienced their FPA at home. In this study, patients were classified by the location of their FPA and the differences in their clinical features were explored (e.g., symptoms of FPA, frequency of agoraphobia, and severity of FPA).

Methods

The subjects comprised 830 panic disorder patients who were classified into 5 groups based on the place of their FPA (home, school/office, driving a car, in a public transportation vehicle, outside of home), The clinical features of these patients were investigated. Additionally, for panic disorder patients with agoraphobia at their initial clinic visit, the clinical features of patients who experienced their FPA at home were compared to those who experienced their attack elsewhere.

Results

In comparison of the FPAs of the 5 groups, significant differences were seen among the 7 descriptors (sex ratio, drinking status, smoking status, severity of the panic attack, depression score, ratio of agoraphobia, and degree of avoidance behavior) and 4 symptoms (sweating, chest pain, feeling dizzy, and fear of dying). The driving and public transportation group patients showed a higher incidence of co-morbid agoraphobia than did the other groups. Additionally, for panic disorder patients with co-morbid agoraphobia, the at-home group had a higher frequency of fear of dying compared to the patients in the outside-of-home group and felt more severe distress elicited by their FPA.

Conclusion

The results of this study suggest that the clinical features of panic disorder patients vary according to the place of their FPA. The at-home group patients experienced "fear of dying" more frequently and felt more distress during their FPA than did the subjects in the other groups. These results indicate that patients experiencing their FPA at home should be treated with a focus on the fear and distress elicited by the attack.

Dimensions of anxiety sensitivity in the anxiety disorders: evaluation of the ASI-3

Anxiety sensitivity (AS), the fear of sensations of anxious arousal based on beliefs about their harmful consequences, is increasingly recognized as a multidimensional construct. The recently developed Anxiety Sensitivity Index-3 [ASI-3; Taylor, S., Zvolensky, M., Cox, B., Deacon, B., Heimberg, R., Ledley, D. R., et al. (2007). Robust dimensions of anxiety sensitivity: Development and initial validation of the Anxiety Sensitivity Index-3 (ASI-3). Psychological Assessment, 19, 176-188] measures three dimensions of AS: physical concerns, social concerns, and cognitive concerns. The ASI-3 shows promise, although further evaluation of its psychometric properties and validity in independent samples is needed. We evaluated the ASI-3 in a mixed sample of anxiety disorder patients (N=506) and undergraduate student controls (N=315). The measure demonstrated a stable 3-factor structure and sound psychometric properties, with the three factors showing theoretically consistent patterns of associations with anxiety symptoms and diagnoses. ASI-3 total scores were less discriminative. Implications for conceptual models of anxiety are discussed.

Panic disorder: a review of DSM-IV panic disorder and proposals for DSM-V

This review covers the literature since the publication of DSM-IV on the diagnostic criteria for panic attacks (PAs) and panic disorder (PD). Specific recommendations are made based on the evidence available. In particular, slight changes are proposed for the wording of the diagnostic criteria for PAs to ease the differentiation between panic and surrounding anxiety; simplification and clarification of the operationalization of types of PAs (expected vs. unexpected) is proposed; and consideration is given to the value of PAs as a specifier for all DSM diagnoses and to the cultural validity of certain symptom profiles. In addition, slight changes are proposed for the wording of the diagnostic criteria to increase clarity and parsimony of the criteria. Finally, based on the available evidence, no changes are proposed with regard to the developmental expression of PAs or PD. This review presents a number of options and preliminary recommendations to be considered for DSM-V.

Subtypes of panic attacks: a critical review of the empirical literature

BACKGROUND

Panic disorder is a heterogeneous disorder, comprising a variety of somatic, physiological, and cognitive symptoms during repeated panic attacks. As a result, considerable data have examined whether panic attacks may be classified into distinct diagnostic or functional subtypes. The aim of this study is to evaluate the existing literature regarding the validity of panic attack subtypes.

METHODS

This review focuses on data published since 2000, with the publication of DSM-IV-TR, augmented by replicated data published since 1980, with the publication of DSM-III and subsequently DSM-IV. Published reports evaluating empirical evidence for the validity of panic attack subtypes are reviewed.

RESULTS

Five sets of panic symptoms (respiratory, nocturnal, nonfearful, cognitive, and vestibular) have been shown to cluster together at varying degrees of consistency. However, none of these potential subtypes have been associated with sufficient and reliable external validation criteria indicative of functional differences. This apparent lack of findings may be related to methodological inconsistencies or limitations across the reviewed studies.

CONCLUSIONS

Although at present the data do not warrant the utility of subtyping, further research aimed at patent gaps in the literature, including clearer operationalization of symptom subtypes, greater use of biological challenge paradigms and physiological and other more objective measures of fear and anxiety, and exploration of subtyping based on biological factors such as genetics, may support the future designation of panic attack subtypes and their ultimate clinical utility.

The association between bodily anxiety symptom dimensions and the scales of the Revised NEO Personality Inventory and the Temperament and Character Inventory

The association between anxiety disorders and different measures of personality has been extensively studied to further the understanding of etiology, course, and treatment, and to possibly prevent the development of anxiety disorders. We have proposed a hierarchical model of bodily anxiety symptoms with 1 second-order severity factor and 5 first-order factors: cardio-respiratory, gastro-intestinal, autonomic, vertigo, and tension. The aim of this study was to investigate whether personality traits were differentially related to distinct symptom subdimensions or exclusively related to the general severity factor. Structural equation modeling of data on 120 patients with a primary diagnosis of social phobia and 207 patients with a primary diagnosis of panic disorder was used to examine the association between anxiety symptom dimensions and the scales of the Temperament and Character Inventory and of the Revised NEO Personality Inventory. When both sets of personality measures were simultaneously modeled as predictors, the Revised NEO Personality Inventory scales, neuroticism and extraversion, remained significantly associated with the severity factor, whereas the association between the Temperament and Character Inventory dimensions, harm avoidance and novelty seeking, and the severity factor became nonsignificant. Harm avoidance was negatively associated with the vertigo first-order factor, whereas neuroticism was negatively associated with the cardio-respiratory first-order factor, indicating that personality factors may be differentially related to specific anxiety subdimensions.

Carbon dioxide-induced emotion and respiratory symptoms in healthy volunteers

A number of evidences have established that panic and respiration are closely related. Clinical studies indicated that respiratory sensations constitute a discrete cluster of panic symptoms and play a major role in the pathophysiology of panic. The aim of the present study was to explore the phenomenology of an experimental model of panic in healthy volunteers based on the hypothesis that: (1) we can isolate discrete clusters of panic symptoms, (2) respiratory symptoms represent a distinct cluster of panic symptoms, and (3) respiratory symptoms are the best predictor of the subjective feeling of panic, as defined in the DSM IV criteria.Sixty-four healthy volunteers received a double inhalation of four mixtures containing 0, 9, 17.5 and 35% CO(2,) respectively, in a double-blind, cross-over, random design. An electronic visual analog scale and the Panic Symptom List (PSL) were used to assess subjective 'fear/discomfort' and panic symptoms, respectively. Statistical analyses consisted of Spearman's correlations, a principal component factor analysis of the 13 PSL symptoms, and linear regressions analyses.The factor analysis extracted three clusters of panic symptoms: respiratory, cognitive, and neurovegetative (r(2)=0.65). Respiratory symptoms were highly related to subjective feeling of fear/discomfort specifically in the CO(2)-enriched condition. Moreover, the respiratory component was the most important predictor of the subjective feeling of 'fear/discomfort' (beta=0.54).The discrete clusters of symptoms observed in this study were similar to those elicited in panic attacks naturally occurring in patients affected by panic disorder. Consistent with the idea that respiration plays a crucial role in the pathophysiology of panic, we found that respiratory symptoms were the best predictors the subjective state defined in the DSM IV criteria for panic.

Is the association of hypertension and panic disorder explained by clustering of autonomic panic symptoms in hypertensive patients?

BACKGROUND

Autonomic nervous system dysfunction may be implicated in the association of hypertension with panic attacks and panic disorder. We hypothesised that panic symptoms of autonomic origin are more common in attacks experienced by hypertensive than normotensive patients, that autonomic panic symptoms cluster together as a distinct factor, and that this factor is more prevalent in hypertensive patients with panic than in normotensives.

METHODS

We analysed all 346 structured questionnaires completed by primary care and hospital clinic patients who had reported experiencing full (n=287) or limited symptom panic attacks (n=59) (268 with hypertension, and 78 never having had hypertension). Frequency of sweating, flushes, and racing heart, symptoms selected prospectively as being most likely of autonomic origin, were compared between hypertensive and normotensive patients. Principal component analysis was performed with varimax orthogonal rotation. Using logistic regression, odds ratios were calculated for association of factor scores with hypertension.

RESULTS

Sweating and flushes were significantly more common among hypertensive patients than normotensives (sweating; 65% v 46%, p=0.003, flushes; 55% v 40%, p=0.019). There was no significant difference between groups for frequency of racing heart nor any of the remaining panic symptoms analysed as secondary endpoints. Principal component analysis yielded four factors with eigenvalues >1.0. Factor 1 was dominated by autonomic symptoms, notably sweating and flushes, which had loadings of 0.68 and 0.61. On regression only this autonomic factor showed a significant association with hypertension, the odds ratio being 1.37 (95% C.I. 1.05 to 1.77, p=0.018).

CONCLUSIONS

These findings support the possibility that autonomic dysfunction contributes to the association of hypertension with panic.

Chest pain and its importance in patients with panic disorder: an updated literature review

CONTEXT

Chest pain is a common symptom in primary care settings, associated with considerable morbidity and health care utilization. Failure to recognize panic disorder as the source of chest pain leads to increased health care costs and inappropriate management.

OBJECTIVE

To identify characteristics of the chest pain associated with the presence of panic disorder, review the consequences and possible mechanisms of chest pain in panic disorder, and discuss the recognition of panic disorder in patients presenting with chest pain.

DATA SOURCES

Potential studies were identified via a computerized search of MEDLINE and PsycINFO databases and review of bibliographies. MeSH headings used included panic disorder with chest pain, panic disorder with coronary disease or cardiovascular disorders or heart disorders, and panic disorder with cholesterol or essential hypertension or tobacco smoking.

STUDY SELECTION

The diagnosis of panic disorder in eligible studies was based on DSM criteria, and studies must have used objective criteria for coronary artery disease and risk factors. Only case control and cohort studies were included.

DATA SYNTHESIS

Although numerous chest pain characteristics (believed to be both associated and not associated with coronary artery disease) have been reportedly linked to panic disorder, only nonanginal chest pain is consistently associated with panic disorder (relative risk = 2.03, 95% CI = 1.41 to 2.92).

CONCLUSION

Chest pain during panic attacks is associated with increased health care utilization, poor quality of life, and phobic avoidance. Because the chest pain during panic attacks may be due to ischemia, the presence of panic attacks may go unrecognized. Ultimately, the diagnosis of panic disorder must be based on DSM criteria. However, once panic disorder is recognized, clinicians must remain open to the possibility of co-occurring coronary artery disease.

Evaluation of diagnostic criteria for panic attack using item response theory: findings from the National Comorbidity Survey in USA

BACKGROUND

The dichotomous diagnostic systems such as the Diagnostic and Statistical Manual of Mental Disorders (DSM) and International Classification of Diseases (ICD) lose much important information concerning what each symptom can offer. This study explored the characteristics and performances of DSM-IV and ICD-10 diagnostic criteria items for panic attack using modern item response theory (IRT).

METHODS

The National Comorbidity Survey used the Composite International Diagnostic Interview to assess 14 DSM-IV and ICD-10 panic attack diagnostic criteria items in the general population in the USA. The dimensionality and measurement properties of these items were evaluated using dichotomous factor analysis and the two-parameter IRT model.

RESULTS

A total of 1213 respondents reported at least one subsyndromal or syndromal panic attack in their lifetime. Factor analysis indicated that all items constitute a unidimensional construct. The two-parameter IRT model produced meaningful and interpretable results. Among items with high discrimination parameters, the difficulty parameter for "palpitation" was relatively low, while those for "choking," "fear of dying" and "paresthesia" were relatively high. Several items including "dry mouth" and "fear of losing control" had low discrimination parameters.

LIMITATIONS

The item characteristics of diagnostic criteria among help-seeking clinical populations may be different from those that we observed in the general population and deserve further examination.

CONCLUSIONS

"Paresthesia," "choking" and "fear of dying" can be thought to be good indicators of severe panic attacks, while "palpitation" can discriminate well between cases and non-cases at low level of panic attack severity. Items such as "dry mouth" would contribute less to the discrimination.

Depersonalization and individualism: the effect of culture on symptom profiles in panic disorder

It has been proposed that highly individualistic cultures confer vulnerability to depersonalization. To test this idea, we carried out a comprehensive systematic review of published empirical studies on panic disorder, which reported the frequency of depersonalization/derealization during panic attacks. It was predicted that the frequency of depersonalization would be higher in Western cultures and that a significant correlation would be found between the frequency of depersonalization and individualism scores of the participant countries. As predicted, the frequency of depersonalization during panic was significantly lower in nonwestern countries. There was also a significant correlation between frequency of depersonalization and Individualism (rho = 0.68, p < 0.0001), and between fears of losing control (rho = 0.57, p = 0.005) and individualism. These findings are interpreted in light of recent studies suggesting that individualistic cultures are characterized by hypersensitivity to threat and by an external locus of control. Two features may be relevant in the genesis of depersonalization.

Carbon dioxide inhalation induces dose-dependent and age-related negative affectivity

Background

Carbon dioxide inhalation is known to induce an emotion similar to spontaneous panic in Panic Disorder patients. The affective response to carbon dioxide in healthy subjects was not clearly characterized yet.

Methodology/Principal Findings

Sixty-four healthy subjects underwent a double inhalation of four mixtures containing respectively 0, 9, 17.5 and 35% CO₂ in compressed air, following a double blind, cross-over, randomized design. Affective responses were assessed according to DSM IV criteria for panic, using an Electronic Visual Analogue Scale and the Panic Symptom List. It was demonstrated that carbon dioxide challenges induced a dose dependent negative affect (p<0.0001). This affect was semantically identical to the DSM IV definition of panic. Older individuals were subjectively less sensitive to Carbon Dioxide (p<0.05).

Conclusions/Significance

CO₂ induced affectivity may lay on a continuum with pathological panic attacks. Consistent with earlier suggestions that panic is a false biological alarm, the affective response to CO₂ may be part of a protective system triggered by suffocation and acute metabolic distress.

Anxiety sensitivity within the anxiety disorders: Disorder-specific sensitivities and depression comorbidity

The tendency to perceive anxious states as aversive and harmful is hypothesized to confer vulnerability to the development of anxiety disorders. The most commonly used measure of anxiety sensitivity, the Anxiety Sensitivity Index [ASI; Reiss, S., Peterson, R.A., Gursky, D.M., & McNally R.J. (1986). Anxiety sensitivity, anxiety frequency, and the prediction of fearfulness. Behavior Research and Therapy, 24, 1-8], is composed of multiple lower-order factors, assessing fear of physical symptoms, fear of publicly observable anxious symptoms, and fear of cognitive dyscontrol. This study examined the convergent validity of the lower-order anxiety sensitivity dimensions in DSM-IV diagnosed anxiety disorders. Participants with primary diagnoses of panic disorder with agoraphobia, social phobia, and generalized anxiety disorder (GAD) completed the ASI and measures of anxiety and depression severity. Support was found for the convergent validity of all ASI dimensions in reference to thematically related anxiety disorders and in the identification of patients presenting with and without secondary major depressive disorder (MDD). The ASI-fear of cognitive dyscontrol dimension displayed strong and nonredundant associations with GAD, dimensional depression scores, and secondary diagnoses of MDD. The conceptual implications of the shared importance of fear of cognitive dyscontrol in GAD and MDD are discussed.

Ictal symptoms of anxiety, avoidance behaviour, and dissociation in patients with dissociative seizures

OBJECTIVE

To examine anxiety related seizure symptoms and avoidance behaviour in adults with dissociative (psychogenic non-epileptic) seizures (DS) in comparison with a group suffering from partial epilepsy.

METHODS

25 DS and 19 epilepsy patients completed an attack symptom measure, the hospital anxiety and depression scale, the dissociative experiences scale, and the fear questionnaire.

RESULTS

DS patients reported the presence of significantly greater numbers of somatic symptoms of anxiety during their attacks than the epilepsy group, despite not reporting subjectively higher levels of anxiety. The DS patients also reported higher levels of agoraphobic-type avoidance behaviour than the epilepsy group. Measures of dissociation were higher in the DS group, who also reported greater symptoms of depression.

CONCLUSIONS

The findings support a model whereby DS occur as a paroxysmal, dissociative response to heightened arousal in the absence of raised general anxiety levels. The model has practical implications for clinical assessment and treatment: in clinical practice, inquiry about these symptoms may help in the diagnosis of DS; with respect to treatment, the anxiety related symptoms and avoidance behaviour prevalent in DS are a potential focus for a cognitive behavioural approach analogous to that used in the treatment of other anxiety disorders.

Panic disorder phenomenology in urban self-identified Caucasian-Non-Hispanics and Caucasian-Hispanics

The epidemiology of panic disorder is well known, but data about some phenomenological aspects are sparse. The symptom criteria for panic disorder were developed largely from rational expert consensus methods and not from empirical research. This fact calls attention to the construct validity of the panic disorder diagnosis, which may affect accuracy of epidemiological findings. Seventy self-identified Non-Hispanic-Caucasian (Anglo) and Hispanic-Caucasian (Hispanic) people who were diagnosed with DSM-III-R panic disorder with or without agoraphobia were invited to complete a Panic Phenomenological Questionnaire (PPQ), which was constructed for this study from the Hamilton Anxiety Scale Items and The DSM-III-R panic symptoms. Fifty (71%) subjects agreed to participate, and there was no response bias detected. Seven symptoms on the PPQ that are not in the DSM-IV diagnostic criteria were reported to occur with a high prevalence in this study. Furthermore, many symptoms that occurred with a high frequency and were reported to be experienced as severe are also not included in current nosology. A few of the DSM-IV criterion symptoms occurred with low prevalence, frequency, and severity. Cognitive symptoms were reported to occur with higher frequency and severity during attacks than autonomic or other symptoms. There were modest differences between ethnic groups with regard to panic attack phenomena. Further research using multiple empirical methods aimed at improving the content validity of the panic disorder diagnosis is warranted. This includes utilizing consistent methods to collect data that will allow for rational decisions about how to construct valid panic disorder criteria across cultures.

A study of the phenomenology of panic attacks in patients from India

We studied the symptom structure of panic attacks in 94 patients attending an outpatient psychiatric clinic. Autonomic symptoms of anxiety were reported by the majority of the panic patients. As compared with studies from the West, certain cognitive symptoms, such as fear of loss of control and depersonalization, and vestibular symptoms were endorsed by fewer panic patients. The majority of our panic patients tended to seek help initially from physicians and medical specialists. The majority of the patients also did not experience some DSM-IV symptoms as part of their panic attacks. Comorbid psychiatric conditions influenced the symptom structure of panic attacks. A higher number of agoraphobics as compared with patients with uncomplicated panic disorders had the symptoms of fear of loss of control and fainting. Our findings support the notion that the experience of panic attacks is variable and differs across cultures.

Syndrome profiles in alcoholism and panic disorder with or without agoraphobia: an explorative family study

It is proposed that alcoholism and panic disorder/agoraphobia demonstrate in part common genetic and environmental origins. Shared subthreshold symptom patterns in the parents' generation could confirm the proposed genetic role in alcoholism and panic disorder/agoraphobia, even if the parents do not fulfil the diagnostic criteria for a primary psychiatric diagnosis. This is the first family study of exploratively analyzing subthreshold symptoms in both disorders. The authors investigated families with panic disorder/agoraphobia and/or alcoholism with the Munich-Composite International Diagnostic Interview (M-CIDI). We documented the diagnoses according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria and subdivided the answers of the probands into 16 subthreshold diagnostic groups comprising 259 single items. We found statistically significant correlations of subthreshold syndrome profiles in the parents of patients with panic disorder/agoraphobia and alcoholism. The presented method of analyzing syndrome profiles in a family study seems to be a possibility to demonstrate references to genetic links between patients and parents in anxiety- and alcohol-related disorders.

A review of psychological factors/processes affecting anxious responding during voluntary hyperventilation and inhalations of carbon dioxide-enriched air

Despite advances in our understanding of the nature of anxiety-related responding during periods of elevated bodily arousal, it is not necessarily evident by what psychological mechanisms anxiety is produced and maintained. To address this issue, researchers have increasingly employed biological challenge procedures to examine how psychological factors affect anxious responding during elevated bodily arousal. Of the challenging procedures, hyperventilation and inhalations of carbon dioxide-enriched air have been among the most frequently employed, and a relatively large body of literature using these procedures has now accumulated. Unfortunately, existing reviews do not comprehensively examine findings from hyperventilation and inhalations of carbon dioxide studies, and only rarely the methodological issues specific to these studies. To address these issues, we review the voluntary hyperventilation and carbon dioxide-enriched air literature in order to identify the primary methodological issues/limitations of this research and address the extent to which psychological variables influence anxious responding to such challenges. Overall, we conclude challenge research is a promising paradigm to examine the influence of psychological variables in anxious responding, and that such work will likely be enhanced with greater attention to psychological process issues.

Adaptation as a sensorial profile in trait anxiety: a study with virtual reality

Twenty-four volunteers were recruited on the basis of their trait anxiety scores (low trait anxiety [LTA] and high trait anxiety [HTA]) as assessed by the State-Trait Anxiety Inventory. Adaptation to conflicting visual-vestibular stimulation (VVS) was used to study integration of space-related multi-sensory information in trait anxiety. First, vestibular perception was assessed by rotating the blindfolded subjects about the vertical axis (horizontal plane rotations) on a remote-controlled mobile robot. The subjects were asked to indicate the perceived rotation by use of an angular pointer. Subjects were then immersed into the center of a visual virtual square room by means of a head-mounted display. They were asked to control the robot with a joystick in order to perform 90 degrees rotations in the virtual room. However, a gain of 0.5 was introduced between visual scene and robot rotation so that the subjects were submitted to a conflict situation in which the 90 degrees rotational visual input was concurrent with a 180 degrees vestibular input. After 45 min of training with the virtual reality display, subjects were tested again in total darkness in order to determine whether their vestibular system had been reset by the conflicting visual signals. We found significant differences in adaptation to VVS between HTA and LTA groups as well as between males and females. Subjects of the HTA group demonstrated larger adaptation than that of the LTA group. Males also showed a greater level of adaptation compared to females. Our results suggest greater visual dependence in HTA subjects. This might be important for understanding the mechanisms underlying pathological anxiety and particularly agoraphobia.

Panic disorder among Cambodian refugees attending a psychiatric clinic. Prevalence and subtypes

This study surveys Khmer refugees attending two psychiatric clinics to determine both the prevalence of panic disorder as well as panic attack subtypes in those suffering panic disorder. A culturally valid adaptation of the SCID-panic module, the Cambodian Panic Disorder Survey (CPDS), was administered to 89 consecutive Cambodian refugees attending these psychiatric clinics. Utilizing culturally sensitive panic probes, the CPDS provides information regarding both the presence of panic disorder and panic-attack subtypes during the month prior to interview. Of 89 patients surveyed at two psychiatric clinics, 53 (60%) currently suffered panic disorder. Among the 53 patients suffering panic disorder, the most common panic attack subtypes during the previous month were the following: "sore neck" [51% of the 53 panic disorder patients (PDPs)], orthostatic dizziness (49% of PDPs), gastrointestinal distress (26% of PDPs), effort induced (21% of PDPs), olfactory induced (21% of PDPs), and "while-sitting dizziness" (16% of PDPs).

Evoking analogue subtypes of panic attacks in a nonclinical population using carbon dioxide-enriched air

The increasing recognition that panic attacks are heterogeneous phenomena necessitates better and more objective criteria to define and examine what constitutes a panic attack. The central aim of the present study was to classify subtypes of panic attacks (i.e. prototypic, cognitive, and non-fearful) in a nonclinical sample (N = 96) based on the concordance/discordance between subjective and physiological responding to multiple inhalations of 20 and 13% CO2-enriched air. Results show that a substantial proportion of this nonclinical sample (55.2%) responded to the CO2 challenge in a manner consistent with clinical and research definitions of different subtypes of panic attacks. The implications of this dimensional approach for discriminating subtypes of panic in the laboratory are discussed as a means to better understand the phenomenology and nature of panic attacks.

Depersonalization in panic disorder: a clinical study

Panic disorder (PD) has been hypothesized to be a heterogeneous entity, with distinct clinical subgroups. The presence of depersonalization during panic attacks may distinguish a specific subgroup of PD. We sought to analyze the differential features of a subgroup of PD patients with depersonalization. A total of 274 patients with PD were assessed and divided into 2 groups according to the presence or absence of depersonalization. The Structured Clinical Interview for DSM-III-R (SCID-UP-R) was used to assess PD and comorbid disorders. The clinical scales administered included the Hamilton Anxiety and Depression Rating Scale (HARS and HDRS), the Marks and Mathews Fears and Phobia Scale, Panic-Associated Symptom Scale (PASS), and a panic attack symptoms inventory. A total of 66 patients (24.1%) exhibited depersonalization during the attacks. Patients with depersonalization appeared to be younger and had an earlier age at onset. PD was more severe in the depersonalization group (greater number of attacks, worse level of functioning, and higher scores on most self-rating scales). Also, depersonalization patients showed more comorbidity with specific phobia. Our results support the view that PD with depersonalization may be considered a distinct and more severe subcategory of PD.

Differential clinical features of late-onset panic disorder

OBJECTIVES

The aim was to analyse the sociodemographic and clinical characteristics of panic disorder (PD) in patients with a PD onset after 60 years of age, at two outpatient psychiatric clinics in Barcelona (northeastern Spain).

MATERIAL AND METHODS

All patients presenting with PD at two outpatient clinics over a 4-year period were assessed by the same team. Patients with PD onset at 60 or after were grouped (late-onset), and compared with the group with an earlier onset. The instruments administered to the sample were: Global Assessment of Functioning scale, Panic-Associated Symptom Scale, Hamilton's Depression and Anxiety Scales and Marks-Matthews' Fear and Phobia scale.

RESULTS

Of 5301 patients attended over a 4-year period, 64 (1.2%) were PD patients aged 60 or above. Age at PD onset was over 60 in 27 cases (0.4% of the total population, and 6.1% of all PD patients). The mean age in the late-onset group was 67.0+/-4.9 years. Late-onset PD patients were less likely to report family history of PD. They scored lower on most scales assessing clinical severity (excepting GAF and agoraphobia scores), and they exhibited fewer and milder panic symptoms during the attacks. However, dysthymic disorder, but not major depressive disorder, was more common among late-onset PD patients (P<0.05).

COMMENTS

The most notable findings in our late-onset PD subgroup of patients were: lesser severity of the disorder, greater comorbidity with dysthymia, and less family history of PD. Prevalence rates of late-onset PD in our sample appeared to be rather high. Physical illness and less severe panic symptoms may contribute to underdiagnosing PD in this particular subpopulation.

Differential clinical features of early-onset panic disorder

BACKGROUND

Although panic disorder (PD) begins typically in adulthood, an earlier onset is not uncommon. Recent studies on early-onset PD indicate that this subgroup of patients may display distinct clinical characteristics.

OBJECTIVE

To compare a subgroup of early-onset PD patients with the rest of the sample.

METHOD

A consecutive series of 442 patients with PD were included. Family histories were investigated, and clinical assessment employed the following instruments: Hamilton's scales, Global Functioning Scale, Marks-Mathews' Fears and Phobia Scale, and Panic-Associated Symptom Scale. The age threshold for 'early-onset' was considered at 18 years.

RESULTS

A total of 45 patients (10.2%) exhibited early-onset PD, with a mean age at onset of 14.6. They were younger and had a longer duration of illness than later-onset patients. No differences were found in severity of panic symptoms, anxiety or depressive symptoms, and social functioning. They had more comorbidity with simple phobia, social phobia, and substance dependence. Rates of PD among first-degree relatives were higher in the early-onset group.

CONCLUSION

Early-onset PD patients displayed a greater familial loading, but clinical severity of their panic-agoraphobia symptoms was not higher. Comorbidity was greater with phobic and substance-related disorders.

Semiology and subtyping of panic disorders

To date, the quantitative psychopathology of panic disorder (PD) has been less well studied than that of other psychiatric conditions such as schizophrenia or major depression. The aim of the present study was to assess the frequency and factorial grouping of symptoms in a naturalistic sample of PD patients. A total of 274 consecutive cases of PD who contacted an out-patient clinic in Barcelona, Spain were assessed by two experienced interviewers. The assessment instruments included the Structured Clinical Interview for DSM-III-R Upjohn version (SCID-UP-R) and an inventory of panic attack symptoms based on DSM-III-R. Of the patients who presented at the unit during the assessment period, 8.5% presented with PD. Palpitations, shortness of breath, fear of dying and dizziness were the most frequent and intense symptoms reported by the PD patients. Principal-component analysis revealed four factors which accounted for 57% of the variance, including 'cardiorespiratory' (26.1%) and 'vestibular' (15.1%) factors, and two additional factors with mixed symptoms. The frequency of presentation of symptoms was similar to that reported in other studies. However, some discrepancies were observed that may be attributed to transcultural differences as well as to terminological problems and the range of symptoms assessed. These factors may also explain some of the differences found in factor analysis groupings in previous studies. Our findings support the symptom subtyping of PD.

Towards a 'map' of panic: structure of the bodily symptoms

Despite the large amount of research on panic attacks according to DSM criteria, there are some inconsistencies between this and reports from clinical settings. Some naturalistic and non-standard studies are needed. The authors of the present study submitted a list of 24 bodily symptoms to 65 panic patients who had sought medical help. The results of principal-component analysis revealed five factors, four of which represent the forms described in clinical and epidemiological contexts: cephalo-vertiginous, cervico-respiratory, thoraco-cardiac and abdomino-digestive. Each of these factors is differentially related to some specific fearful anticipations, which may organize the symptoms in a body-related topographical way.

Anxiety sensitivity: multiple dimensions and hierarchic structure

Anxiety sensitivity (AS) is the fear of anxiety-related sensations, based on beliefs that these sensations have harmful consequences. AS is thought to play an important role as a diathesis for anxiety disorders, particularly panic disorder. Recent evidence suggests that AS has a hierarchical structure, consisting of multiple lower-order factors, which load on a single higher-order factor. If each factor corresponds to a discrete mechanism, then the results suggest that AS arises from a hierarchic arrangement of mechanisms. A problem with previous studies is that they were based on the 16-item Anxiety Sensitivity Index (ASI), which may not contain enough items to reveal the type and number of lower-order factors. Accordingly, we developed the 60-item Anxiety Sensitivity Profile, which was administered to 349 university students. Factor analyses revealed four lower-order factors: (1) Fear of respiratory symptoms, (2) fear of cognitive dyscontrol, (3) fear of gastrointestinal symptoms, and (4) fear of cardiac symptoms. These loaded on a single higher-order factor. The lower-order factors shared variance with the higher-order factor, but also contained unique variance. Thus, the results suggest that AS is the product of a general factor, with independent contributions from four specific factors.

The assessment of panic using self-report: a comprehensive survey of validated instruments

A repertoire of reliable and valid self-report instruments to assess panic and panic disorder would help both researchers and clinicians. This review presents a description and an analysis of the available instruments. Following a comprehensive search of the literature, 14 instruments with published information on reliability and validity were reviewed. The following information is reported for each instrument: brief description of the instrument and its development, mean and standard deviation for clinical and nonclinical samples, and psychometric properties. Four types of instruments are presented: general assessment and information (n = 2), severity of panic disorder (n = 2), body sensations (n = 2) and cognitive dimensions of panic (n = 8). Overall, it would seem that panic measures have moderate to excellent psychometric qualities. However, the comparison between the instruments is difficult because the amount of empirical support available varies widely from one instrument to the other.

Depersonalization and derealization during panic and hypnosis in low and highly hypnotizable agoraphobics

The primary aim of the present study was to investigate the association between spontaneous experiences of depersonalization or derealization (D-D) during panic states and hypnosis in low and highly hypnotizable phobic individuals. Secondarily, the association among level of hypnotizability, capacity for imaginative involvement, and severity of phobic complaints was also assessed. Sixty-four patients with panic disorder with agoraphobia according to the DSM-III-R (American Psychiatric Association, 1987) criteria participated in the study. Proneness to experience D-D during hypnosis was positively related to hypnotizability, but only for agoraphobic patients who had already experienced these perceptual distortions during panic episodes. Correlations of level of hypnotizability and capacity for imaginative involvement with severity of agoraphobic complaints were not significant. These findings suggest that hypnotizability may be a mediating variable between two different, although phenotypically similar, perceptual distortions experienced during panic states and hypnosis. Implications for both theory and clinical practice are discussed.

Does the Beck Anxiety Inventory measure anything beyond panic attack symptoms?

The Beck Anxiety Inventory (BAI) has become a popular measure in anxiety assessment and the BAI does not overlap in content with measures of depression. There is also some factor analytic evidence to support this distinction. However, an inspection of the BAI's content indicates that many of its items resemble, or are identical to, the symptoms of panic attacks listed in the DSM-IV. Further empirical support for this suspicion is provided from the results of a factor analysis of the BAI items and the individual DSM-IV panic symptoms contained in the Panic Attack Questionnaire, using data from a sample of 157 panic disorder patients. A three-factor model (dizziness related, catastrophic cognitions/fear, cardiorespiratory distress) emerged that replicated a three-factor model of panic symptoms identified in earlier work with another panic disorder sample. All but one of the BAI items loaded highly on the three panic symptom clusters and no separate BAI factor was obtained. The BAI appears to be confounded with, or actually measures, panic attacks rather than anxiety in general. Several implications of this finding are discussed.

Phenomenology of panic attacks: responsiveness of individual symptoms to imipramine

A number of studies have demonstrated that individual panic symptoms are not equivalent vis-a-vis their clinical salience. This study investigated the proposition that individual panic symptoms may also differ in their specific responsiveness to treatment in 63 patients with panic disorder with agoraphobia who had completed an 8-week placebo-controlled dose-ranging study with imipramine. The results revealed that fear, unreality, and respiratory symptoms, most strongly dyspnea and choking, displayed the highest degree of early differentiation between effective and ineffective doses of the drug, whereas palpitations, tingling, and sweating had the most pronounced effects between weeks 4 and 8 of treatment. On the other hand, the symptom of hot and cold flashes did not differ between adequate and inadequate treatment. The evidence presented reinforces the notion that individual panic symptoms are not functionally equivalent and suggests that some symptoms, in particular fear, derealization, and the respiratory symptoms, may be more central than others to the therapeutic process just as some of them have been found to be more important for diagnostic considerations. The results are briefly discussed from the methodologic and phenomenologic perspectives.