Respiratory disorders as a possible predisposing factor for 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.

Lifelong opioidergic vulnerability through early life separation: a recent extension of the false suffocation alarm theory of panic disorder

The present paper is the edited version of our presentations at the "First World Symposium On Translational Models Of Panic Disorder", in Vitoria, E.S., Brazil, on November 16-18, 2012. We also review relevant work that appeared after the conference. Suffocation-False Alarm Theory (Klein, 1993) postulates the existence of an evolved physiologic suffocation alarm system that monitors information about potential suffocation. Panic attacks maladaptively occur when the alarm is erroneously triggered. The expanded Suffocation-False Alarm Theory (Preter and Klein, 2008) hypothesizes that endogenous opioidergic dysregulation may underlie the respiratory pathophysiology and suffocation sensitivity in panic disorder. Opioidergic dysregulation increases sensitivity to CO2, separation distress and panic attacks. That sudden loss, bereavement and childhood separation anxiety are also antecedents of "spontaneous" panic requires an integrative explanation. Our work unveiling the lifelong endogenous opioid system impairing effects of childhood parental loss (CPL) and parental separation in non-ill, normal adults opens a new experimental, investigatory area.

Baseline respiratory parameters in panic disorder: a meta-analysis

BACKGROUND

The presence of abnormalities in baseline respiratory function of subjects with panic disorder (PD) is expected according to PD respiratory theories. We aimed to meta-analyze results from studies comparing baseline respiratory and hematic parameters related to respiration between subjects with PD and controls.

METHODS

A literature research in bibliographic databases was performed. Fixed-effects models were applied for all parameters while random-effects models only when suitable (at least 10 independent studies). Several moderator analyses and publication bias diagnostics were performed.

RESULTS

We found significantly higher mean minute ventilation and lower et-pCO(2) in subjects with PD than controls. Moreover we also found evidences of reduced HCO(3)(-) and PO(4)(-) hematic concentrations, higher indexes of respiratory variability/irregularity and higher rate of sighs and apneas. Evidence of heterogeneity was partly explained by moderator analyses. No relevant publication bias was found.

LIMITATIONS

Several shortcomings affected the included studies, such as over-inclusive recruitment criteria, samples unbalanced for socio-demographic characteristics, lack of statistical details and small number of studies available for several parameters.

DISCUSSION

Our results support the idea of abnormalities in respiratory function of subjects with PD. Compared to controls, they showed baseline hyperventilation; the results from hematic parameters suggest that hyperventilation may be chronic and not simply caused by their high anxiety levels during respiratory assessment. Evidences of higher variability and irregularity in respiratory patterns of subjects with PD were also found. It is unclear to what extent the higher rate of sighs and apneas may explain the other baseline respiratory abnormalities found in PD.

Health anxiety and fear of fear in panic disorder and agoraphobia vs. social phobia: a prospective longitudinal study

BACKGROUND

This study is aimed to evaluate the role of two vulnerability factors, health anxiety and fear of fear, in the prediction of the onset of panic disorder/agoraphobia (PDA) relative to a comparison anxiety disorder.

METHODS

Young women, aged between 18 and 24 years, were investigated at baseline and, 17 months later, using the Anxiety Disorders Interview Schedule-Lifetime and measures of health anxiety and fear of bodily sensations (subscale disease phobia of the Whiteley Index, and total score of the Body Sensations Questionnaire). First, 22 women with current PDA were compared to 81 women with current social phobia and 1,283 controls. Second, 24 women with an incidence of PDA were compared to 60 women with an incidence of social phobia and 1,036 controls.

RESULTS

Multiple logistic regression analyses adjusted for history of physical diseases, somatic symptoms, and other psychological disorders revealed that (a) fear of bodily sensations was elevated for women with PDA vs. controls as well as women with social phobia, and (b) health anxiety (and history of physical diseases) was elevated in women who developed PDA vs. controls and vs. women who developed social phobia.

CONCLUSIONS

These results suggest that health anxiety, as well as history of physical diseases, may be specific vulnerability factors for the onset of PDA relative to social phobia. Whereas fear of bodily sensations was not found to be a risk factor for the onset of panic disorder/agoraphobia, it was a specific marker of existing PDA relative to social phobia.

Challenging anxiety: a focus on the specificity of respiratory symptoms

Physiological symptoms are characteristic features of anxiety states. Presumably, specific psychophysiological profiles differentiate between anxiety disorders, which would offer potential for diagnostic purposes. Abundant evidence points to a causal relationship between panic disorder and instability of respiratory regulation. However, the specificity of most measures that indicate aberrant functioning of the respiratory system in PD can be questioned. Possibly, the traditional measures of respiratory functioning are too restricted. The underlying respiratory vulnerability in PD seems to constitute a subtle, unstable trait, which calls for more sensitive and sophisticated measures of respiratory variability and chaos. To increase the probability of finding parameters with diagnostic specificity, the application of disorder specific challenge paradigms is recommended.

Understanding panic disorder in chronic respiratory disease

As well as being physically debilitating, respiratory diseases present significant challenges to the psychological well-being of individuals and their families and are recognized to have an impact on health-care services, resources and time. Panic attacks and disorder are particularly prevalent in people with respiratory conditions and appear to be associated with reduced lung function. However, recent evidence suggests that the aetiology of panic in this area may be related more to underlying psychological processes, which can influence cognitions that are related to the experience of respiratory disease and its symptoms. The aim of this article is to give a brief overview of the literature to identify key psychological factors associated with panic and respiratory diseases. The article concludes that panic has a complex aetiology, which requires the presence of specific respiratory-related cognitions. The self-regulatory model can foster understanding of the combination of beliefs/cognitions that can increase the prevalence of negative mood for patients with respiratory diseases.

Respiratory patterns in panic disorder reviewed: a focus on biological challenge tests

OBJECTIVE

To provide a systematic review of studies investigating respiration in PD and comments on relative inconsistencies.

METHOD

A Medline search of controlled studies focusing on pCO(2), respiratory rate, tidal volume, and minute volume in PD patients was conducted for baseline/resting condition, challenge, and recovery phase. Respiratory variability and comparisons between panickers and non-panickers were also examined.

RESULTS

Lower pCO(2) levels in PD subjects are a consistent finding during the baseline/resting condition, the challenge, and recovery phases. Tidal volume and minute volume are increased in PD subjects relative to controls during the baseline/resting condition. However, the most robust finding is a higher than normal respiratory variability, which appears to be a promising factor for the identification of respiratory etiopathological pathways in PD.

CONCLUSION

Respiratory variability might be a candidate for a biological marker of PD: an abnormal breathing pattern as found in panic disorder (PD) patients compared with controls might indicate instability of the respiratory homeostasis.

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.

Panic, suffocation false alarms, separation anxiety and endogenous opioids

This review paper presents an amplification of the suffocation false alarm theory (SFA) of spontaneous panic [Klein DF (1993). False suffocation alarms, spontaneous panics, and related conditions. An integrative hypothesis. Arch Gen Psychiatry; 50:306-17.]. SFA postulates the existence of an evolved physiologic suffocation alarm system that monitors information about potential suffocation. Panic attacks maladaptively occur when the alarm is erroneously triggered. That panic is distinct from Cannon's emergency fear response and Selye's General Alarm Syndrome is shown by the prominence of intense air hunger during these attacks. Further, panic sufferers have chronic sighing abnormalities outside of the acute attack. Another basic physiologic distinction between fear and panic is the counter-intuitive lack of hypothalamic-pituitary-adrenal (HPA) activation in panic. Understanding panic as provoked by indicators of potential suffocation, such as fluctuations in pCO(2) and brain lactate, as well as environmental circumstances fits the observed respiratory abnormalities. However, that sudden loss, bereavement and childhood separation anxiety are also antecedents of "spontaneous" panic requires an integrative explanation. Because of the opioid system's central regulatory role in both disordered breathing and separation distress, we detail the role of opioidergic dysfunction in decreasing the suffocation alarm threshold. We present results from our laboratory where the naloxone-lactate challenge in normals produces supportive evidence for the endorphinergic defect hypothesis in the form of a distress episode of specific tidal volume hyperventilation paralleling challenge-produced and clinical panic.

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.

Race/ethnicity, income, chronic asthma, and mental health: a cross-sectional study using the behavioral risk factor surveillance system

OBJECTIVE

To examine the relationships among race/ethnicity, income, and asthma on mental health outcomes in individuals surveyed as part of the Centers for Disease Control and Prevention 2004 Behavioral Risk Factor Surveillance System (BRFSS). Racial and ethnic disparities in asthma prevalence exist, which may be explained in part by socioeconomic status. Individuals with asthma often have comorbid mental health conditions, the rates of which are also marked by significant racial and ethnic disparities.

METHODS

We obtained 2004 BRFSS demographic, asthma, and mental health data on Hispanics, non-Hispanic Whites, and non-Hispanic Blacks. Linear regression analysis was used to examine the main and interaction effects of race/ethnicity, income, and history of asthma on poor mental health (n = 282,011), as well as on depression (n = 14,907) and anxiety (n = 14,871) specifically.

RESULTS

A significant three-way interaction emerged among race/ethnicity, income, and history of chronic asthma on number of days of poor mental health. Among the most impoverished (income <$15,000/yr), Hispanics with asthma reported greater number of days of poor mental health than non-Hispanic Whites with asthma. However, among those with slightly greater economic resources, Hispanics with asthma reported fewer number of days of poor mental health than non-Hispanic Whites.

CONCLUSIONS

The results of this study highlight the complex interactions among race/ethnicity, income, and asthma on mental health outcomes.

Panic disorder, phobias, and generalized anxiety disorder

This chapter provides a review of recent empirical developments, current controversies, and areas in need of further research in relation to factors that are common as well as specific to the etiology and maintenance of panic disorder, phobias, and generalized anxiety disorder. The relative contribution of broad risk factors to these disorders is discussed, including temperament, genetics, biological influences, cognition, and familial variables. In addition, the role that specific learning experiences play in relation to each disorder is reviewed. In an overarching hierarchical model, it is proposed that generalized anxiety disorder, and to some extent panic disorder, loads most heavily on broad underlying factors, whereas specific life history contributes most strongly to circumscribed phobias.

Changes in respiratory symptoms and health-related quality of life

BACKGROUND

For a number of chronic diseases, health-related quality of life (HRQoL) has become an important outcome measure. Little data are available on how incidence, remission, or persistence of respiratory symptoms affect HRQoL.

METHODS

The Hordaland County Cohort Study was conducted between 1985 and 1997, and comprised 3,786 subjects, randomly selected, and aged 15 to 70 years in 1985. Respiratory symptoms were assessed both in 1985 and 1996/1997, and HRQoL was measured by the Short-Form 12 questionnaire in 1996/1997. Robust linear regression analysis was used to examine the relationship between changes in six respiratory symptoms and the physical component score (PCS) and mental component score (MCS).

RESULTS

Among subjects with incidence or persistence of any of the six examined respiratory symptoms, PCS and MCS were significantly lower than among subjects without symptoms. The PCS was more reduced than the MCS in symptomatic subjects; however, this trend was reduced after adjustment for the confounder's gender, age, educational level, body mass index, and smoking status. Dyspnea attacks and dyspnea grade 2 had the largest negative impact on both PCS and MCS.

CONCLUSIONS

This is the first longitudinal population study to show the negative impact of incidence and persistence of respiratory symptoms on HRQoL.

The relationship between the severity of asthma and comorbidites with anxiety and depressive disorders

OBJECTIVE: There is evidence that asthma is associated with increased frequency of psychiatric symptoms and mental disorders. Our aim was to assess the frequency of anxiety and depressive disorders in a sample of asthmatic outpatients and observe if there is any relationship between this comorbidity and the severity of asthma. METHOD: Sixty-two consecutive patients of two outpatient asthma clinics located in university hospitals were evaluated. Psychiatric diagnoses were assessed with the Mini-International Neuropsychiatric Interview 4.4 Version. RESULTS: Twenty-seven patients (43.5%) met criteria for at least one psychiatric diagnosis. The most frequent diagnoses were major depression (24%), generalized anxiety disorder (20.9%) and panic disorder/agoraphobia spectrum disorders (17.7%). We found no significant differences in the prevalence of anxiety disorders and depression between the groups with mild/moderate and severe asthma. Despite the high frequency of depression and anxiety disorders, only 4 (6.5%) patients were under psychiatric treatment and 13 (20.9%) patients were taking benzodiazepines. Twelve of 15 (80%) patients who reported present use of psychotropic medication were not under psychiatric treatment at the moment of the study. CONCLUSIONS: Our results support the high morbidity of anxiety and depressive disorders in asthmatic patients, independent of the severity of asthma.

Neuroticism moderates the effect of maximum smoking level on lifetime panic disorder: a test using an epidemiologically defined national sample of smokers

The present study evaluated a moderational model of neuroticism on the relation between smoking level and panic disorder using data from the National Comorbidity Survey. Participants (n=924) included current regular smokers, as defined by a report of smoking regularly during the past month. Findings indicated that a generalized tendency to experience negative affect (neuroticism) moderated the effects of maximum smoking frequency (i.e., number of cigarettes smoked per day during the period when smoking the most) on lifetime history of panic disorder even after controlling for drug dependence, alcohol dependence, major depression, dysthymia, and gender. These effects were specific to panic disorder, as no such moderational effects were apparent for other anxiety disorders. Results are discussed in relation to refining recent panic-smoking conceptual models and elucidating different pathways to panic-related problems.

Acute nicotine withdrawal symptoms and anxious responding to bodily sensations: A test of incremental predictive validity among young adult regular smokers

Although previous work has found associations between panic and smoking, little research has investigated potential mechanisms by which smoking may contribute to panic problems. The present investigation evaluated the incremental validity of acute nicotine withdrawal symptoms (elicited by an average of 2h of nicotine deprivation) relative to negative affectivity, anxiety sensitivity, and nicotine dependence in predicting anxiety responding to 3-min voluntary hyperventilation. The sample consisted of 90 regular smokers (46 females), as defined by smoking >or= 10 cigarettes per day for at least 1 year, recruited through the general community. Consistent with prediction, greater levels of pre-challenge nicotine withdrawal symptoms uniquely predicted post-challenge intensity of panic symptoms and anxiety relative to other established factors. Findings are discussed in the context of how regular smoking may promote panic symptomotology.

Prevalence of respiratory disorders in first-degree relatives of panic disorder patients

BACKGROUND

Panic Disorder (PD) patients often report a history of respiratory pathology, such as asthma. It is known that both PD and respiratory disorders, like asthma, run in families. A common diathesis for PD and some respiratory disorders may be present both in PD patients and their first-degree relatives. We examined whether the lifetime prevalence of respiratory disorders is higher in first-degree relatives of PD patients than in first-degree relatives of patients with other anxiety disorders.

METHODS

The lifetime history of respiratory pathology was assessed in 379 first-degree relatives of patients with an anxiety disorder by means of a questionnaire.

RESULTS

We found the first-degree relatives of PD patients to report more chronic obstructive pulmonary diseases (COPD) in general (24.8%) and asthma (10.5%) in particular than the comparison group (13.2% and 3.3%, respectively).

LIMITATIONS

Our data rely on retrospective self-reports.

CONCLUSIONS

Our findings are consistent with and extend previous studies suggesting a specific association between COPD, asthma in particular, and PD.

Cognitive-behavioral treatment combined with asthma education for adults with asthma and coexisting panic disorder

This study tested the efficacy of a nurse-administered 8-week group treatment program for adults with asthma suffering from coexisting panic disorder. The program consisted of cognitive behavioral treatment (CBT) for panic disorder combined with asthma education (AE). Forty-eight women with a confirmed diagnosis of asthma and panic disorder were randomly allocated to a treatment condition (n=25) and a wait-list control condition (n=23). Twenty-five participants--15 in the treatment group and 10 in the wait-list control group--completed treatment. Repeated measures ANOVA procedures were used to compare the groups on panic and asthma outcomes at posttreatment and 6-month follow-up. The results demonstrate that the CBT-AE program is capable of producing substantial and durable antipanic and antianxiety treatment effects and led to substantial but nonsustained improvement in morning peak-flow expiratory rate and asthma-related quality of life. Implications of these findings for this clinical population are addressed.

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.

Smoking and respiratory irregularity in panic disorder

BACKGROUND

The biological mechanisms underlying the link between smoking and panic attacks are unknown. Smoking might increase the risk of panic by impairing respiratory system function.

METHODS

We evaluated the effect of smoking on respiratory irregularity in patients with panic disorder (PD) and healthy comparison subjects and the role of the respiratory disorders in this effect. We applied the Approximate Entropy index (ApEn), a nonlinear measure of irregularity, to study breath-by-breath baseline respiratory patterns in our sample.

RESULTS

Both smoker and nonsmoker patients had more irregular respiratory patterns than healthy subjects. Smoker patients showed higher ApEn indices of baseline respiratory rate and tidal volume than nonsmoker patients (R = 5.4, df = 2,55, p < .01), whereas smoking in healthy subjects did not influence the regularity of respiratory patterns. Respiratory disorders did not account for the influence of smoking on respiratory irregularity. Smokers had more severe panic attacks than nonsmokers.

CONCLUSIONS

Smoking may impair vulnerable respiratory function and act as disruptive factor on intrinsic baseline respiratory instability in patients with PD, possibly influencing the onset or maintenance of the disorder.

Applied cognitive psychology: Implications of cognitive psychology for clinical psychology and psychotherapy

Cognitive psychology has made numerous contributions to clinical psychology, and these contributions are considered especially with reference to the anxiety disorders. It is argued that there are four major contributions that can be identified. First, the cognitive approach has led to the development of complex models showing the main cognitive processes and structures of relevance to an understanding of anxiety disorders. Second, controlled laboratory studies permit a more detailed investigation of cognitive biases in anxious patients than generally is feasible in more naturalistic settings. Third, the cognitive approach provides relevant evidence with respect to the issue of whether cognitive biases play a role in the development and maintenance of anxiety disorders. Fourth, the enhanced understanding of the anxiety disorders that has arisen from the cognitive approach has had beneficial effects on therapeutic practice in a number of significant ways. In sum, it is claimed that clinical psychology has benefited considerably from cognitive theory and research.

Panic disorder: from respiration to the homeostatic brain

There is some experimental evidence to support the existence of a connection between panic and respiration. However, only recent studies investigating the complexity of respiratory physiology have revealed consistent irregularities in respiratory pattern, suggesting that these abnormalities might be a vulnerability factor to panic attacks. The source of the high irregularity observed, together with unpleasant respiratory sensations in patients with panic disorder (PD), is still unclear and different underlying mechanisms might be hypothesized. It could be the result of compensatory responses to abnormal respiratory inputs or an intrinsic deranged activity in the brainstem network shaping the respiratory rhythm. Moreover, since basic physiological functions in the organism are strictly interrelated, with reciprocal modulations and abnormalities in cardiac and balance system function having been described in PD, the respiratory findings might arise from perturbations of these other basic systems or a more general dysfunction of the homeostatic brain. Phylogenetically ancient brain circuits process physiological perceptions/sensations linked to homeostatic functions, such as respiration, and the parabrachial nucleus might filter and integrate interoceptive information from the basic homeostatic functions. These physiological processes take place continuously and subconsciously and only occasionally do they pervade the conscious awareness as 'primal emotions'. Panic attacks could be the expression of primal emotion arising from an abnormal modulation of the respiratory/homeostatic functions.

Vulnerability to 35% CO2 of panic disorder patients with a history of respiratory disorders

Patients with panic disorder often report a history of respiratory pathology. Furthermore, panic disorder patients are vulnerable to CO2 challenges. The increased CO2 vulnerability displayed by panic disorder patients may be related to lifetime respiratory pathology. We examined whether panic disorder patients with a history of respiratory disorders are more vulnerable to a 35% CO2 challenge than those without such a history. Ninety-six patients with panic disorder were interviewed about their lifetime respiratory status (asthma, bronchitis and various other respiratory conditions) and underwent the challenge. Immediately before and after the CO2 inhalation, the patients filled out the Visual Analogue Scale for Anxiety (VAS-A) and the Panic Symptom List (PSL). We found no differences between the two panic disorder groups on anxiety (VAS-A), panic symptoms (PSL) or panic attacks after the CO2 challenge. Our results suggest that having a PD is an important factor in CO2 vulnerability independent of a history of respiratory disorders.

Psychological aspects of asthma

Asthma can be affected by stress, anxiety, sadness, and suggestion, as well as by environmental irritants or allergens, exercise, and infection. It also is associated with an elevated prevalence of anxiety and depressive disorders. Asthma and these psychological states and traits may mutually potentiate each other through direct psychophysiological mediation, nonadherence to medical regimen, exposure to asthma triggers, and inaccuracy of asthma symptom perception. Defensiveness is associated with inaccurate perception of airway resistance and stress-related bronchoconstriction. Asthma education programs that teach about the nature of the disease, medications, and trigger avoidance tend to reduce asthma morbidity. Other promising psychological interventions as adjuncts to medical treatment include training in symptom perception, stress management, hypnosis, yoga, and several biofeedback procedures.

Psychiatric disorders in asthmatic outpatients

It has been reported that the lifetime prevalence of panic disorder in patients with pulmonary disease is higher than epidemiologic estimates of population prevalence. We evaluated the frequency of anxiety disorders in 86 subjects from the Outpatient Asthma Clinic. Psychiatric diagnoses were assessed with the Mini-International Neuropsychiatric Interview 4.4 Version (MINI). Forty-five asthmatic patients (52.3%) reported at least one current anxiety disorder. The frequency of panic disorder with or without agoraphobia was 13.9% (n=12) and that of agoraphobia without panic disorder was 26.8% (n=23). Social anxiety and generalized anxiety disorders occurred in 9.3% (n=8) and 24.4% (n=21) of the sample, respectively. Twenty-nine patients (33.7%) reported a major depressive episode. The psychiatric morbidity of the sample was 61.6% (n=53). Our results tend to support the high morbidity of anxiety disorders, particularly panic/agoraphobic spectrum disorders, in asthmatic outpatients.

Screening and assessing adult asthmatics for anxiety disorders

The purpose of this study was to evaluate a strategy designed to permit early detection of anxiety disorders in asthmatics. Ninety-one adult asthmatics were screened for anxiety disorders using the Sheehan Patient Rated Anxiety Scale (SPRAS) and the Anxiety Sensitivity Index (ASI) and then individually evaluated by a nurse trained in the administration of the Anxiety Disorders Interview Schedule-IV (ADIS-IV. Thirty-five (38%) of the participants met the diagnostic criteria for one or more anxiety disorders. Comparison of the SPRAS and ASI findings revealed that the SPRAS was more effective in detecting asthmatics likely to be suffering from coexisting anxiety disorders. Comparison of the nurses diagnostic formulations with those of an expert revealed that trained nurses using the ADIS-IV can diagnose anxiety disorders in the asthmatic population with a high degree of accuracy. These results have implications for resolving the problem of unrecognized and untreated anxiety disorders in the asthmatic population.

Paths to panic disorder/agoraphobia: an exploratory analysis from age 3 to 21 in an unselected birth cohort

OBJECTIVE

To evaluate childhood temperamental traits and early illness experiences in the etiology of adult panic disorder with agoraphobia.

METHOD

Evaluated temperamental and illness experience factors, at ages 3 through 18, as predictors of panic and agoraphobia at ages 18 or 21 in an unselected sample (N = 992). Analyses were conducted with classification trees.

RESULTS

Experience with respiratory ill health predicted panic/agoraphobia relative to other anxiety disorders and healthy controls. Also, temperamental emotional reactivity at age 3 predicted panic/agoraphobia in males but did not predict other anxiety disorders, compared with healthy controls. Furthermore, temperament and ill health interacted with gender.

CONCLUSIONS

Results are discussed in terms of cognitive theories of fear of physical symptoms and biological models of respiratory disturbance for panic/agoraphobia.

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.

Experimental pathophysiology of panic

In this article, we review how the knowledge of the pathophysiology of panic disorder has expanded, with special emphasis on laboratory models using lactate and carbon dioxide challenges. Experiments in the late 1960s revealed that lactate infusion can induce panic attacks. A prominent feature of these attacks is hyperventilation. Because lactate infusion induces a metabolic alkalosis, one would rather expect a compensatory hypoventilation. For years hyperventilation was thought to be causally linked to panic, but it has since been proven to be a symptom rather than a cause of panic attacks. Similarly, it is not hypocapnia but hypercapnia that has proven to be capable of provoking panic attacks. Carbon dioxide challenges are comparable to lactate infusion in the degree to which they meet the criteria for an ideal model of panic disorder. Experiments with carbon dioxide in first-degree relatives of panic disorder patients and in monozygotic twins support the idea of a constitutional predisposition to panic disorder. Of the various other agents that have been used to trigger panic attacks, cholecystokinin seems particularly promising as a valid laboratory model of panic disorder and may provide valuable data regarding the mechanism of panic attacks. The false suffocation alarm theory, proposed by Klein, is an integrative hypothesis that may account for a large number of the laboratory as well as clinical observations.

Comorbid depressive disorder increases vulnerability to the 35% carbon dioxide (CO2) challenge in panic disorder patients

BACKGROUND

The hypothesis of this study was that panic disorder patients with a comorbid depressive disorder would be less vulnerable to the 35% CO2 panic provocation challenge than panic disorder patients without a comorbid depressive disorder. This hypothesis was based on findings from ventilatory response studies in depressive patients.

METHODS

Twelve panic disorder patients with and 23 panic disorder patients without a comorbid depressive disorder were challenged.

RESULTS

Panic disorder patients with a comorbid depressive disorder scored significantly higher on ratings of subjective anxiety and panic symptoms induced by the challenge.

CONCLUSIONS

A comorbid depressive disorder appeared to increase the vulnerability of panic disorder patients to this panic provocation.

LIMITATION

We did find significant differences, but these differences did not confirm the original hypothesis.

CLINICAL RELEVANCE

Our results support clinical data that show that a comorbid depressive disorder correlates with an increased severity of panic disorder.

Asthma and panic attacks

Panic disorder (PD) and asthma share many common characteristics and have been found in epidemiological studies to be significantly comorbid. To investigate possible reasons for this overlapping, the authors evaluated 51 patients with asthma, assessing the prevalence of PD and sporadic panic attacks, the temporal relationship between these two disorders, and the familial risk for PD in the families of asthmatics. The results showed significantly higher prevalences of PD, sporadic panic attacks, and social phobia in asthmatics than those reported for the general population. In 9 (90%) of the asthmatics with PD, asthma appeared first. Finally, the morbidity risk for PD in families of asthmatics with PD (13.5%) was significantly higher than in families of asthmatics without evidence of panic (2%). Our results suggest that the high prevalence of PD in asthmatics might be related to a facilitating effect of asthma on the development of PD in subjects with familial predisposition to PD.

Physiological, biochemical and subjective parameters in anxiety patients with panic disorder during stress exposure as compared with healthy controls

Physiological (heart rate, blood pressure, electrodermal activity), biochemical (epinephrine, norepinephrine, cortisol) and subjective parameters (self-rating score) of 33 patients with panic disorder (diagnoses according to DSM-III-R) before, during and after stress exposure were compared with those of healthy controls. As stressors a video containing frightening scenes (FS), mental arithmetic (MA), a video documenting a patient suffering from a panic attack (PA) and an improvised speech (IS) were applied. We found significantly higher baseline levels of electrodermal activity (EDA) and norepinephrine (NE) secretion and a subsequent further increase during stress exposure in panic disorder patients as compared with normal controls. The most potent stressors during the trial proved to be mental arithmetics and improvised speech, which was evident in both groups. The situation panic attack video appeared to be a "panic disorder patient-specific" stressor; here we noticed the most pronounced reactions in the patient group. Panic disorder patients had significantly higher self-rating scores of the parameters panicky feelings, anxiety and nervousness at the beginning and throughout the investigation. We conclude that panic disorder patients have a higher degree of activation compared with normal controls, which is evident regarding levels of electrodermal activity and norepinephrine secretion. Furthermore, the panic attack video appears to be a panic disorder patient-specific stressor.

Is there a specific relationship between asthma and panic disorder?

The objective of the present study was three-fold: (1) to assess the prevalence of PD in asthmatic patients in comparison with non-asthmatic patients; (2) to investigate possible differences in pulmonary function and anxiety symptomatology between asthmatic patients with PD and those without; and (3) to evaluate possible differences in symptom perception during histamine-induced bronchoconstriction between asthmatic patients with PD versus asthmatic controls without PD matched for age, sex and bronchial responsiveness to histamine (PC20). The study was performed on 123 consecutive patients referred to the lung function laboratory of a university hospital for a histamine challenge test. Firstly, baseline measures for FEV1, anxiety (ADIS-R, ACQ, BSQ, and STAI) and depression (SDS) were collected. Subsequently, before and during induced bronchoconstriction FEV1, perceived breathlessness (Borg scale), subjective anxiety (SUDS), and somatic panic symptoms (PAQ) were assessed. The prevalence of PD in asthmatic patients, although higher than in the general population, was very similar to the rate observed in non-asthmatic patients. Baseline level of FEV1 and bronchial responsiveness to histamine (PC20) were also not significantly different between asthmatic patients with and without PD. Moreover, in comparison with matched controls, PD cases reported significantly higher levels of perceived breathlessness during induced bronchoconstriction, although their mean fall in FEV1 was very comparable. It is concluded that the higher prevalence of PD in asthma is non-specific and probably due to selection bias.