The symptom structure of panic disorder: a trial using factor and cluster analysis

The relationship of separation anxiety with the age of onset of panic disorder

AIM

This study aimed to investigate whether separation anxiety (SA) constitutes a dimension related to age at onset of panic disorder (PD), in homogeneous subgroups of outpatients with PD, based on their age of onset and symptom severity.

METHODS

A sample of 232 outpatients with PD was assessed with the Panic Disorder Severity Scale (PDSS) and the Sheehan Disability Scale (SDS) for functional impairments. Separation anxiety was evaluated using structured interviews and questionnaires. We applied a K-Means Cluster Analysis based on the standardized "PD age of onset" and "the PDSS total score" to identify distinct but homogeneous groups.

RESULTS

We identified three groups of patients: group 1 ("PD early onset/severe", N = 97, 42%, onset 23.2 ± 6.7 years), group 2 ("PD early onset/not severe", N = 76, 33%, onset 23.4 ± 6.0 years) and group 3 ("PD adult onset/not severe", N = 59, 25%, onset 42.8 ± 7.0 years). Patients with early onset/severe PD had significantly higher scores on all SA measures than PD late-onset/not severe. Regression analyses showed that SA scores, but not PDSS scores, were predictive of impairment in SDS work/school, social life, and family functioning domains.

CONCLUSIONS

Our data indicate a significant relationship between SA and PD with an earlier age of onset and an impact on individual functioning. This may have important implications for implementing preventive interventions targeting early risk factors for the subsequent onset of PD.

Posterior subthalamic nucleus (PSTh) mediates innate fear-associated hypothermia in mice

The neural mechanisms of fear-associated thermoregulation remain unclear. Innate fear odor 2-methyl-2-thiazoline (2MT) elicits rapid hypothermia and elevated tail temperature, indicative of vasodilation-induced heat dissipation, in wild-type mice, but not in mice lacking Trpa1-the chemosensor for 2MT. Here we report that Trpa1-/- mice show diminished 2MT-evoked c-fos expression in the posterior subthalamic nucleus (PSTh), external lateral parabrachial subnucleus (PBel) and nucleus of the solitary tract (NTS). Whereas tetanus toxin light chain-mediated inactivation of NTS-projecting PSTh neurons suppress, optogenetic activation of direct PSTh-rostral NTS pathway induces hypothermia and tail vasodilation. Furthermore, selective opto-stimulation of 2MT-activated, PSTh-projecting PBel neurons by capturing activated neuronal ensembles (CANE) causes hypothermia. Conversely, chemogenetic suppression of vGlut2+ neurons in PBel or PSTh, or PSTh-projecting PBel neurons attenuates 2MT-evoked hypothermia and tail vasodilation. These studies identify PSTh as a major thermoregulatory hub that connects PBel to NTS to mediate 2MT-evoked innate fear-associated hypothermia and tail vasodilation.

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.

Panic attacks and panic disorder in the American Indian community

Panic disorder is a common mental health condition, but little is known about panic disorder in non-Caucasian populations. The purpose of this study is to describe the epidemiology, clinical features, and comorbidities of panic attacks and panic disorder in two large American Indian (AI) tribes (N=3084). A culturally-adapted version of the Composite International Diagnostic Interview assessed panic attacks, panic disorder, and various psychiatric comorbidities. After adjusting for age, gender, and tribe, linear and logistic regression analyses were conducted to compare AIs with panic disorder to those with panic attacks only on clinical characteristics and panic symptoms. Approximately 8.5% (N=234) of American Indians reported a lifetime history of panic attacks. Among individuals with panic attacks, comorbid posttraumatic stress disorder was higher in females (p=0.03) and comorbid alcohol-related disorders were higher in males (p≤0.001). The prevalence and clinical features of panic attacks and panic disorder in American Indians were similar to epidemiologic studies with majority populations. However, in contrast to earlier research, panic symptoms were similar in both males and females, and different patterns of comorbidity emerged. Future research should examine the availability and accessibility of evidence-based panic treatments for this traditionally underserved population.

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.

Does 'fear of dying' indicate a more severe presentation of panic disorder?

Research suggests a relationship between the presence of fearful cognitions and panic disorder (PD) severity. With little existing evidence addressing the clinical significance of individual panic-cognitions, the current study examined presentation and impairment differences among 331 outpatients with PD according to whether they experience "fear of dying" (FOD) during panic attacks. Patients reporting FOD (n=153) were compared to patients denying FOD (n=178) on variables indicating PD severity (e.g., number of symptoms) and psychiatric impairment (e.g., hospitalizations). PD patients with FOD reported a greater number of panic symptoms, agoraphobia diagnoses, and were more likely to be seeking treatment primarily for PD. We found no clinical impairment or comorbidity differences between groups. Results suggest that panic attacks with FOD are related to a more acute presentation of PD. Such results substantiate past research connecting cognitive distress and PD severity and further suggest that FOD may be particularly relevant to this relationship.

Translational approach to studying panic disorder in rats: hits and misses

Panic disorder (PD) patients are specifically sensitive to 5–7% carbon dioxide. Another startling feature of clinical panic is the counterintuitive lack of increments in ‘stress hormones’. PD is also more frequent in women and highly comorbid with childhood separation anxiety (CSA). On the other hand, increasing evidence suggests that panic is mediated at dorsal periaqueductal grey matter (DPAG). In line with prior studies showing that DPAG-evoked panic-like behaviours are attenuated by clinically-effective treatments with panicolytics, we show here that (i) the DPAG harbors a hypoxia-sensitive alarm system, which is activated by hypoxia and potentiated by hypercapnia, (ii) the DPAG suffocation alarm system is inhibited by clinically-effective treatments with panicolytics, (iii) DPAG stimulations do not increase stress hormones in the absence of physical exertion, (iv) DPAG-evoked panic-like behaviours are facilitated in neonatally-isolated adult rats, a model of CSA, and (v) DPAG-evoked responses are enhanced in the late diestrus of female rats. Data are consistent with the DPAG mediation of both respiratory and non-respiratory types of panic attacks.

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.

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.

Reducing anxiety in stutterers through the association between "purpose in life/Ikigai" and emotions

The prefrontal lobe is more evolved in humans than in other mammals. The functioning of human prefrontal lobes promotes an innate need to establish a meaningful life, often referred to as “Purpose in life (PIL)/ikigai.” PIL/ikigai and the prefrontal lobe psychologically and physiologically, respectively, shape ambition, regulate the development of emotions and integrate psychological events. PIL/ikigai contributes to both a reduction in the anxiety caused by a need for approval from others and the stimulation of pleasure and comfort, which may be related to the well-balanced secretion of neurotransmitters such as serotonin, dopamine, and β-endorphin. Thus, if a stutterer aware that articulate speech is advantageous in communication feels a need for social desirability (SD) based on a need for approval from others, they may develop stress and anxiety caused by their perceived failure when engaging in conversations. This feeling of failure may be related to an imbalanced secretion of serotonin and dopamine. Therefore, previous work has suggested that PIL/ikigai may reduce anxiety in stutterers who seek SD by reducing the symptoms associated with stuttering.

Panic disorder respiratory subtype: psychopathology, laboratory challenge tests, and response to treatment

OBJECTIVE

Our objective is to summarize the new findings concerning the respiratory subtype (RS) of panic disorder (PD) since its first description.

METHODS

Two searches were made in the Institute for Scientific Information Web of Science: with the keywords "panic disorder" and "respiratory symptoms," and all articles that cited Briggs and colleagues' 1993 article "Subtyping of Panic Disorder by Symptom Profile" (Br J Psychiatry 1993;163:201-9). Altogether, 133 articles were reviewed.

RESULTS

We describe and discuss RS epidemiology, genetics, psychopathology, demographic features, clinical features, correlations with the respiratory system, traumatic suffocation history, provocative tests, and nocturnal panic. Compared to patients with the nonrespiratory subtype (non-RS), the RS patients had higher familial history of PD, lower comorbidity with depression, longer duration of illness, lower neuroticism scores, and higher scores in severity scales, such as the Panic and Agoraphobia Scale, Panic-Agoraphobia Spectrum scale and the Clinical Global Impression scale. Tests to induce panic attacks, such as those with CO(2), hyperventilation, and caffeine, produce panic attacks in a higher proportion of RS patients than non-RS patients. Differences in the subtypes' improvement with the pharmacologic treatment were found. There are also some controversial findings regarding the RS, including the age of onset of PD, and alcohol and tobacco use in RS patients.

CONCLUSIONS

Some characteristics, such as the increased sensitivity to CO(2) and the higher familial history of PD, clearly distinguish the RS from the non-RS. Nevertheless, there are also controversial findings. More studies are needed to determine the validity of the RS subtype.

Hyperventilation in panic disorder and asthma: empirical evidence and clinical strategies

Sustained or spontaneous hyperventilation has been associated with a variety of physical symptoms and has been linked to a number of organic illnesses and mental disorders. Theories of panic disorder hold that hyperventilation either produces feared symptoms of hypocapnia or protects against feared suffocation symptoms of hypercapnia. Although the evidence for both theories is inconclusive, findings from observational, experimental, and therapeutic studies suggest an important role of low carbon dioxide (CO2) levels in this disorder. Similarly, hypocapnia and associated hyperpnia are linked to bronchoconstriction, symptom exacerbation, and lower quality of life in patients with asthma. Raising CO2 levels by means of therapeutic capnometry has proven beneficial effects in both disorders, and the reversing of hyperventilation has emerged as a potent mediator for reductions in panic symptom severity and treatment success.

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 structure of lifetime panic-agoraphobic spectrum

The heterogeneity of the clinical presentation of panic disorder (PD) has prompted researchers to describe different subtypes of PD, on the basis of the observed predominant symptoms constellation. Starting from a dimensional approach to panic disorder, an instrument to assess lifetime panic-agoraphobic spectrum (PAS) available in interview or self-report form (SCI-PAS, PAS-SR) was developed which proved to have sound psychometric properties and the ability to predict delayed response to treatment in patients with mood disorders. However, the structure of the instrument was defined a priori and an examination of its empirical structure is still lacking. Aim of the present report is to analyse the factor structure of the PAS taking advantage of a large database of subjects with panic disorders (N=630) assessed in the framework of different studies. Using a classical exploratory factor analysis based on a tetrachoric correlation matrix and oblique rotation, 10 factors were extracted, accounting overall for 66.3% of the variance of the questionnaire: panic symptoms, agoraphobia, claustrophobia, separation anxiety, fear of losing control, drug sensitivity and phobia, medical reassurance, rescue object, loss sensitivity, reassurance from family members. The first two factors comprise the DSM-IV criteria for panic disorder and agoraphobia. The other factors had received limited empirical support to date. We submit that these symptoms profiles might be clinically relevant for tailoring drug treatments or psychotherapeutic approaches to specific needs. Future perspectives might include the use of these factors to select homogeneous subgroups of patients for brain-imaging studies and to contribute to elucidating the causes and pathophysiology of panic disorder at molecular level.

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.

Symptomspezifische Subgruppen der Panikstörung

Zusammenfassung. Theoretischer Hintergrund: In Modellen der Panikstörung wird eine erhöhte Sensitivität für körperliche Vorgänge angenommen. Die Spezifität dieser Sensitivität für verschiedene körperliche Funktionsbereiche ist unklar. Dies soll anhand der berichteten Symptome eines Panikanfalls geprüft werden. Methode: Die Angaben von 498 Panikpatienten zu 10 körperlichen Symptomen während eines typischen Panikanfalls (DSM-III-R) wurden Latent Class und Latent Class Faktorenanalysen unterzogen. Ergebnisse: Vier etwa gleichgroße Subgruppen von Panikpatienten mit unterschiedlichen Ausprägungen auf zwei binären Symptomfaktoren wurden identifiziert. Eine Gruppe hatte überwiegend respiratorische Symptome, eine weitere überwiegend vestibuläre Symptome. In den beiden übrigen Gruppen waren alle Symptome gleichermaßen stark bzw. schwach ausgeprägt. Schlussfolgerungen: Zwei der identifizierten Subgruppen scheinen spezifisch sensitiv für respiratorische bzw. vestibuläre Körpervorgänge zu sein. Für die verhaltenstherapeutische Panikbehandlung verweist dieser Befund darauf, spezifische Expositionsübungen zur Steigerung der Erfolgsquoten einzusetzen.

Assessing the clinical utility of agoraphobia in the context of panic disorder

In the DSM-IV, a panic disorder (PD) diagnosis includes specification of agoraphobia, which is primarily an index of situational avoidance due to fear of panic. No other anxiety diagnosis requires specification of level of avoidance. This raises the question as to whether agoraphobia provides unique information beyond the core features of PD (i.e., panic attacks and panic-related worry). The incremental validity of agoraphobia, defined using DSM-IV specifiers versus level of situational avoidance, was examined in relation to the expression and treatment of PD (N=146). Analyses indicate that agoraphobia status adds uniquely to the prediction of PD symptoms, impairment, and response to treatment. However, level of situational avoidance, defined either as a continuous or dichotomous variable, appears to have greater utility compared to the DSM-IV method of classifying agoraphobia. In summary, the agoraphobia specifier seems to have clinical utility but this could be improved by focusing on a dimensional assessment of situational avoidance.

Panic disorder subtypes: further clinical differences

Panic disorder (PD) is a heterogeneous phenomenon with respect to symptom profile. Most studies agree that a group of patients with prominent respiratory symptoms emerged as a distinct PD subtype. In this study we compared a range of clinical features associated with PD and agoraphobia in patients with respiratory (RS) and nonrespiratory (NRS) subtypes of PD. The participants were 124 patients with PD (79 women and 45 men), with or without agoraphobia, diagnosed by DSM-IV criteria. Following the observer-rated Panic Disorder Severity Scale assessment, subjects completed self-report measures, including the Anxiety Sensitivity Index (ASI), Panic-Agoraphobia Scale; the Beck Anxiety Inventory; and the Panic-Agoraphobic Spectrum Scale (PAS-SR). Multivariate analysis of variance (MANOVA) showed significant group differences [Pillai's trace = 0.95, F (5, 118)(=)2.48, P = .036]. Patients in RS group had higher mean total scores on the ASI (F = 5.00, df = 1, P = .027) and PAS-SR (F = 11.23, df = 1, P = .001) than patients in NRS group. Also, patients with RS attained higher scores than patients with NRS on four domains of PAS-SR (panic-like symptoms, agoraphobia, separation sensitivity, and reassurance seeking). A descriptive discriminant analysis of the data correctly identified 69.4% of the patient group in general and 86.1% of RS group (Wilks's lambda = 0.87, df = 8, P = .048). The significant discriminating factors of the RS and NRS groups were domains of panic-like symptoms, agoraphobia, separation sensitivity, and reassurance seeking. Our findings suggest that anxiety sensitivity and panic-agoraphobic spectrum symptoms might be particularly relevant to understanding subtypes of PD.

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.

Evidence for respiratory and nonrespiratory subtypes in panic disorder

Recently researchers have posited a "respiratory" subtype of panic disorder (PD), which differs from "nonrespiratory" subtypes in phenomenology and perhaps treatment response. This study was designed to further examine evidence for the existence of a respiratory subtype in PD. Individuals with PD with prominent respiratory symptoms (PD-R; n=10) and without prominent respiratory symptoms (PD-NR; n=23), as well as healthy controls (n=27), underwent a standardized 5% CO(2) rebreathing challenge. Ventilatory response and subjective sensation of suffocation were continuously recorded. The PD-R group exhibited greater subjective suffocation levels, rates of respiration, and propensity to terminate the procedure voluntarily than did the other two groups, which in turn did not differ on these measures. Findings are consistent with the existence of a respiratory subtype of PD, which differs from nonrespiratory subtypes in CO(2) sensitivity.

Panic attack symptom dimensions and their relationship to illness characteristics in panic disorder

Subtyping panic disorder by predominant symptom constellations, such as cognitive or respiratory, has been done for some time, but criteria have varied considerably between studies. We sought to identify statistically symptom dimensions from intensity ratings of 13 DSM-IV panic symptoms in 343 panic patients interviewed with the Anxiety Disorders Interview Schedule for DSM-IV Lifetime Version. We then explored the relation of symptom dimensions to selected illness characteristics. Ratings were submitted to exploratory maximum likelihood factor analysis with a Promax rotation. A three-factor solution was found to account best for the variance. Symptoms loading highest on the first factor were palpitations, shortness of breath, choking, chest pain, and numbness, which define a cardio-respiratory type (with fear of dying). Symptoms loading highest on the second factor were sweating, trembling, nausea, chills/hot flashes, and dizziness, which defines a mixed somatic subtype. Symptoms loading highest on the third factor were feeling of unreality, fear of going crazy, and fear of losing control, which defines a cognitive subtype. Subscales based on these factors showed moderate intercorrelations. In a series of hierarchical multiple regression analyses, the cardio-respiratory subscale was a strong predictor of panic severity, frequency of panic attacks, and agoraphobic avoidance, while the cognitive subscale mostly predicted worry due to panic. In addition, patients with comorbid asthma had higher scores on the cardio-respiratory subscale. We conclude that partly independent panic symptom dimensions can be identified that have different implications for severity and control of panic disorder.

Depersonalization in psychiatric patients: a transcultural study

There is evidence suggesting that the prevalence of depersonalization in psychiatric patients can vary across cultures. To explore the possible influence of culture on the prevalence of depersonalization, we compared psychiatric inpatient samples from the United Kingdom (N = 31), Spain (N = 68), and Colombia (N = 41) on standardized and validated self-rating measures of dissociation and depersonalization: the Cambridge Depersonalization Scale and the Dissociative Experiences Scale (DES). Colombian patients were found to have lower global scores on the Cambridge Depersonalization Scale and the DES and all its subscales, with the exception of DES-Absorption. No differences were found for measures of depression or anxiety. These findings seem to support the view that depersonalization is susceptible to cultural influences. Attention is drawn to the potential relevance of the sociological dimension "individualism-collectivism" on the experience of the self, and it is proposed that cultures characterized by high individualism may confer vulnerability to depersonalization experiences.

1st International Conference on Panic Attacks: diversity of theories and treatments

The 1st International Conference on Psychophysiology of Panic Attacks focused on the diversity of treatments and theories in this complex condition. Experimental research topics were featured, as well as treatment strategies, case studies and patient perspectives. The conference aimed to create a strong multi-cultural emphasis through international, interdisciplinary and patient-professional interaction. The experimental techniques of lactate provocation of panic, carbon dioxide provocation, respiratory measures and cholecystokinin tetrapeptide infusion were used in various ongoing studies aimed at investigating familial markers, protocols for inducing panic in subjects (including opioid-receptor blockade), brain stem mechanisms involved in mediating anxiety and correlation of respiratory variability with panic severity and treatment outcome. Internet-based questionnaire surveys of panic attack (PA) in subjects that had been sexually abused and of subjective feelings about PAs in patients undergoing fertility treatment were presented, as was a survey of panic epidemiology in Iranian students. Some novel treatment modes were discussed, including non-verbal imagery and art therapy and a telephone-conferencing delivery of cognitive-behavioural therapy. Several case studies were used to illustrate treatments and a personal account of panic disorder combined some time after onset with post-traumatic stress disorder highlighted the different responses of the two disorders to psychotherapies.

Routine use of mental health outcome assessments: choosing the measure

BACKGROUND

There is little consensus about which outcome measures to use in mental healthcare.

AIMS

To investigate the relationship between the items in four staff-rated measures recommended for routine use.

METHOD

Correlation analysis of total scores and factor analysis using combined data from the Health of the Nation Outcome Scales (HoNOS). The Camberwell Assessment of Need Short Appraisal Schedule (CANSAS), the Threshold Assessment Grid (TAG) and the Global Assessment of Functioning (GAF) were performed. Procrustes analysis on factors and scales, and Ward's cluster analysis to group the items, were applied.

RESULTS

The total scores of the measures were moderately correlated. The Procrustes analysis, factor analysis and cluster analysis all agreed on better coverage of the patients' problems by HoNOS and CANSAS.

CONCLUSIONS

A global severity factor accounts for 16% of the variance, and is best measured with TAG or GAF. The CANSAS and HoNOS each provide a detailed characterisation of the patient; only CANSAS provides information about met needs.

Symptom profiles of natural and laboratory panic attacks

BACKGROUND

Little accurate information is available about the symptomatology of real-life panic attacks and about how well they are reproduced by an experimental model such as the 35% CO2 challenge.

METHOD

Real-life panic symptoms were assessed in a group of 67 panic disorder patients, using daily life monitoring. Panic symptoms elicited by a 35% CO2 challenge were assessed in 61 panic disorder patients, and their frequency was compared with the real-life symptoms.

RESULTS

The most frequent real-life symptoms were palpitations, dizziness and trembling. The 35% CO2 challenge reproduced well the majority of real-life symptoms.

CONCLUSION

The findings suggest that the 35% CO2 challenge is a marker for spontaneous panic attacks, which are considered the core of panic disorder.

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.

Respiratory dysregulation in anxiety, functional cardiac, and pain disorders. Assessment, phenomenology, and treatment

Respiration is a complex physiological system affecting a variety of physical processes that can act as a critical link between mind and body. This review discusses the evidence for dysregulated breathing playing a role in three clinical syndromes: panic disorder, functional cardiac disorder, and chronic pain. Recent technological advances allowing the ambulatory assessment of endtidal partial pressure of CO2 (PCO2) and respiratory patterns have opened up new avenues for investigation and treatment of these disorders. The latest evidence from laboratories indicates that subtle disturbances of breathing, such as tidal volume instability and sighing, contribute to the chronic hypocapnia often found in panic patients. Hypocapnia is also common in functional cardiac and chronic pain disorders, and studies indicate that it mediates some of their symptomatology. Consistent with the role of respiratory dysregulation in these disorders, initial evidence indicates efficacy of respiration-focused treatment.

Respiratory and cognitive subtypes of panic. Preliminary validation of Ley's model

A review of the panic disorder literature strongly suggests subtypes of panic attacks, including a respiratory subtype. This study empirically tested several aspects of Ley's panic subtype theory, measuring end-tidal carbon dioxide (ETCO2) levels at baseline, during psychologic and respiratory stressors, and at recovery. As predicted, Type 1 (classic or respiratory) panickers had significantly lower resting ETCO2 compared to Type 3 (cognitive) and to controls. Type 3 panickers did not differ from controls. Physiologic findings support the existence of respiratory and other subtypes of panic attacks in panic disorder. More complex measures of respiration and other physiology are likely required to elicit full subtype profiles. Distinguishing between chronic (compensated) hyperventilators and acute hyperventilators will likely be useful in clarifying the subtypes. Recognizing the need for differential diagnosis of panic attacks can facilitate developing more specific treatment plans and interventions (e.g., restoration of normal ETCO2 in Type 1), improving treatment success rates.

Dyspnea during panic attacks. An Internet survey of incidences of changes in breathing

This article presents the results of a survey that investigated breathing-related symptoms of panic attacks together with the frequency of other symptoms reported by active panickers. All the participants of this study experienced naturally occurring panic attacks and sought treatment guidance by visiting a Web site devoted to the treatment of panic. The results of a symptom questionnaire showed that 195 respondents (95.1%) reported breathing changes during panic attacks, and remarkable dyspnea was reported by more than two thirds (68%) of respondents. These findings are consistent with earlier studies but are contrary to conclusions that only a small number of panickers report shortness of breath as a symptom. This study concludes that outside of the laboratory, a large majority of people who suffer from panic attacks experience symptoms of dyspnea.

The somatic symptom paradox in DSM-IV anxiety disorders: suggestions for a clinical focus in psychophysiology

Although DSM-IV criteria for anxiety disorders include physiological symptoms, these symptoms are evaluated exclusively by verbal report. The current review explores the background for this paradox and tries to demonstrate on theoretical and empirical grounds how it could be resolved, providing new insights about the role of psychophysiological measures in the clinic. The three-systems approach to evaluating anxiety argues that somatic measures as well as verbal and behavioral ones are indispensable. However, the low concordance between these domains of measurement impugns their reliability and validity. We argue that concordance can be improved by examining the relationship of variables less global than anxiety and by restriction to specific anxiety disorders. For example, recent evidence from our and other laboratories indicate a prominent role of self-reported and physiologically measured breathing irregularities in panic disorder. Nonetheless, even within a diagnosis, anxiety patients vary radically in which somatic variables are deviant. Thus, in clinical practice, individual profiles of psychological and physiological anxiety responses may be essential to indicate distinct therapeutic approaches and ways of tracking improvement. Laboratory provocations specific to certain anxiety disorders and advances in ambulatory monitoring vastly expand the scope of self-report and physiological measurement and will likely contribute to a refined assessment of anxiety disorders.

Slow recovery from voluntary hyperventilation in panic disorder

OBJECTIVE

Because hyperventilation has figured prominently in theories of panic disorder (PD) but not of social phobia (SP), we compared predictions regarding diagnosis-specific differences in psychological and physiological measures before, during, and after voluntary hyperventilation.

METHOD

Physiological responses were recorded in 14 patients with PD, 24 patients with SP, and 24 controls during six cycles of 1-minute of fast breathing alternating with 1 minute of recovery, followed by 3 minutes of fast breathing and 10 minutes of recovery. Speed of fast breathing was paced by a tone modulated at 18 cycles/minute, and depth by feedback aimed at achieving an end-tidal pCO2 of 20 mm Hg. These values were reached equally by all groups.

RESULTS

During fast breathing, PD and SP patients reported more anxiety than controls, and their feelings of dyspnea and suffocation increased more from baseline. Skin conductance declined more slowly in PD over the six 1-minute fast breathing periods. At the end of the final 10-minute recovery, PD patients reported more awareness of breathing, dyspnea, and fear of being short of breath, and their pCO2s, heart rates, and skin conductance levels had returned less toward normal levels than in other groups. Their lower pCO2s were associated with a higher frequency of sigh breaths.

CONCLUSIONS

PD and SP patients report more distress than controls to equal amounts of hypocapnia, but PD differ from SP patients and controls in having slower symptomatic and physiological recovery. This finding was not specifically predicted by hyperventilation, cognitive-behavioral, or suffocation alarm theories of PD.

Ataques de pânico provocados pelo dióxido de carbono: estudo clínico-fenomenológico

OBJETIVOS: Verificar a sensibilidade de pacientes com transtorno de pânico (TP) ao teste de indução de ataques de pânico com dióxido de carbono (CO2) a 35% e analisar a intensidade, a duração e a sintomatologia dos ataques de pânico produzidos por esse agente em laboratório, comparando-os com os ataques de pânico espontâneos nesses pacientes. MÉTODOS: Foram selecionados 31 pacientes com TP com ou sem agorafobia (DSM-IV). Após uma semana sem medicação, os pacientes realizavam duas inalações de capacidade vital: uma de mistura carbogênica (CO2 35% e O2 65%) e outra de ar atmosférico comprimido ("placebo"), ordenadas ao acaso e separadas por um intervalo de 20 minutos. Essas inalações eram repetidas após duas semanas. Nesse período, os pacientes não recebiam nenhuma medicação psicotrópica. RESULTADOS: Dos pacientes, 22 (71,0%) apresentaram ataque de pânico em pelo menos um dos testes com CO2. Os sintomas relatados por eles com maior freqüência foram: dificuldade de respirar (n=20, 91,0%), sensação de sufocação/asfixia (n=18, 81,8%), tontura (n=18, 81,8%), estremecimento (n=14, 63,6%), palpitações (n=13, 59,0%) e medo de enlouquecer (n=12, 54,5%). Desse grupo, 11 pacientes (50,0%) consideraram os ataques de pânico experimentados no laboratório mais intensos, comparados aos ataques de pânico espontâneos, quatro (18,2%) consideraram haver a mesma intensidade entre os dois, e sete (31,8%) consideraram o ataque de pânico no laboratório mais leve. CONCLUSÃO: Pacientes com TP têm elevada sensibilidade ao CO2. A inalação de mistura gasosa com 35% de CO2 produz sintomas semelhantes aos ataques de pânico espontâneos, em pacientes com TP. Esse teste pode ser considerado um bom modelo laboratorial para o TP.

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.

Panic disorder subtypes: differential responses to CO2 challenge

OBJECTIVE

The purpose of this study was to investigate the possibility of a differential sensitivity to CO2 in patients diagnosed with panic disorder subtypes that were defined by the presence of prominent respiratory symptoms.

METHOD

The authors used a 35% CO2 and 65% O2 mixture as a challenge agent. Fifty-one unmedicated subjects with DSM-III-R panic disorder, who were divided into respiratory (N = 28) and nonrespiratory (N = 23) subtypes by their symptom profiles, underwent a CO2 challenge procedure. Patients in the two groups were compared with regard to physiological and psychological measures, pulmonary function tests, panic rates, and smoking habits.

RESULTS

The patients in the respiratory group were significantly more sensitive to CO2 than were the patients in the nonrespiratory group. The respiratory group also had higher scores on the Panic and Agoraphobia Scale and had a longer duration of illness; both of these factors can be indicators of illness severity. In addition, the respiratory group's higher cigarette consumption (mean = 12.46 package-years, SD = 2.49) may have been a contributory factor not only for illness severity but also for the pathogenesis of panic disorder.

CONCLUSIONS

The CO2 challenge procedure appears to be a good dissection tool in the understanding of different subtypes of panic disorder. Moreover, there may be a more specific association with prominent respiratory symptom subtype and CO2 hypersensitivity.

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.

Differences in symptom structure between panic attack and limited symptom panic attack: a study using cluster analysis

We had investigated the clinical characteristics of panic disorder (PD) in a Japanese outpatient population comprised of more than 250 patients diagnosed as having PD during a 13-year study period and observed that some PD patients had both panic attacks (PA) and limited symptom panic attacks (LPA). In the criteria for PD based on the Diagnostic and Statistics Manual of Mental Disorders, third edition-revised (DSM-III-R), episodes involving four or more symptoms are classified as PA, while those involving fewer than four symptoms are described as LPA. Therefore, LPA is identified as part of an episode of PA, since the difference between the two episodes is only in the number of symptoms. However, some recent research suggests that there is a distinct subgroup of individuals who suffer LPA. Using cluster analysis, we investigated the differences between PA and LPA groups in terms of the structures of several panic symptoms, which included anticipatory anxiety, agoraphobia and 13 clinical symptoms based on the DSM-III-R at the time of panic attacks, in 247 patients with PD. Cluster analysis revealed clusters of three and four panic symptoms in the PA group and LPA group, respectively, and there were also differences in symptom structure between the two groups. These results suggest that there may be a subgroup of individuals who show LPA among PD patients.