Physiological and symptom responses to hyperventilation: A comparison of frequent and infrequent panickers

Ten subjects with panic disorder and ten subjects with infrequent panic attacks were assessed during 2 min of voluntary hyperventilation using four measures of physiological arousal (heart rate, upper trapezious EMG, skin conductance, and digital skin temperature). Immediately following hyperventilation, subjects were asked to rate their degree of distress on 13 panic symptoms, derived from DSM-III criteria for panic disorder. Results indicated that frequent panickers had significant overall elevations in trapezious EMG, relative to infrequent panickers, and demonstrated a slight increase in muscle tension following hyperventilation. In contrast, infrequent panickers showed a trend toward greater vasodilation preceding and during hyperventilation, with subsequent vasoconstriction upon resumption of normal breathing. Increases in skin conductance and heart rate were noted for both samples during hyperventilation, as reported in prior research. Symptom distress ratings indicated that the infrequent panickers reported significantly greater distress from dizziness and trembling in response to overbreathing, contrary to prediction. Implications of these findings are discussed in light of current accounts of cognitive and physiological factors in the etiology of panic attacks and panic disorder.This research was supported by Biomedical Research Support Grant #507RR07147, National Institutes of Health.     

Hyperventilation and anxiety in panic disorder, social phobia, GAD and normal controls

Patients with DSM-III Agoraphobia, Panic Disorder, GAD, Social Phobia and normal controls underwent a series of experimental procedures and measures to determine whether panic attack patients show a greater tendency towards hyperventilation that is independent from their anxiety levels. Contrary to expectations, the Agoraphobia and Panic Disorder patients did not show significantly lower levels of expired pCO2 at rest than the other anxious or non-anxious groups. However, the panic attack patients did show significantly higher levels of anxiety and hyperventilatory symptoms during a hyperventilation test and during breathing 5% CO2 in air. A strong relationship was found between hyperventilatory symptoms and anxiety in all groups of patients and in the controls. On the basis of these results it was concluded that Agoraphobia and Panic Disorder patients do not show a unique tendency toward hyperventilation, but rather that their hyperventilatory symptoms and perhaps intermittent overbreathing episodes are a function of the high levels of anxiety they experience.     

Nonclinical panic in college students: an investigation of prevalence and symptomatology

This article presents data on the prevalence and symptomatology of panic attacks and panic disorder (PD) in a large nonclinical sample (n = 2,375) of college students. Results showed that approximately 12% of the sample had experienced at least one unexpected panic attack and that 2.36% met DSM-III-R criteria for panic disorder. Although there were no sex differences in overall panic attack prevalence, men reported significantly more panic-related worry than women, and women reported a higher panic frequency than men. Compared to subjects who met DSM-III-R criteria for PD, infrequent panickers presented with fewer panic symptoms, fewer panic episodes, less panic-related worry, lower anxiety sensitivity, and less panic-related avoidance. Moreover, compared with PD subjects, the infrequent panickers were much less likely to report fears of dying, going insane, and derealization during a panic attack. The findings provide preliminary support for the role of anxious apprehension as a psychological vulnerability factor in the pathogenesis of panic disorder.     

Situations and specific coping strategies associated with clinical and nonclinical panic attacks.

The present paper reports the results of further comparisons between clinical and nonclinical panickers. Both panic disorder patients and nonclinical panickers reported a variety of situational contexts associated with panic attacks, and differed markedly in their attempts to cope with panic. Nonclinical panickers tended to use more 'positive' coping strategies in response to panic. Conversely, one of the most commonly used and subjectively effective coping strategies reported by panic disorder patients was to escape the situation.     

The relationship between illness perceptions and panic in chronic obstructive pulmonary disease

BackgroundElevated levels of anxiety and panic are common in respiratory disease. To date the cognitive-behavioural model of panic has been utilised to help explain and manage panic in respiratory disease. This cross-sectional study investigated the relationship between illness perceptions and panic in chronic obstructive pulmonary disease (COPD) within a self-regulatory framework of adaptation to physical illness.MethodsFifty-nine participants with COPD completed questionnaires measuring illness perceptions, anxiety and depression, frequency and severity of panic attacks and impact of disease on daily life and well-being. The percent forced expiratory volume in the first second (FEV₁%) was used as an objective measure of lung function.ResultsHigh levels of clinical anxiety and depression were reported (35% and 19% respectively). Sixty-three percent of participants reported experiencing a panic attack during the previous year and of these 51% during the previous month. Panic was unrelated to level of disease severity. Specific illness perceptions (beliefs relating to illness identity, timeline, consequences and emotional representations) were important in differentiating between panickers and non-panickers.ConclusionsThe results highlight the importance of assessing illness perceptions within the framework of the self-regulatory model to provide an additional theoretical perspective for investigating and managing panic in chronic respiratory disease.     

Anxiety sensitivity and history of panic as predictors of response to hyperventilation

In this study, we examined the effects of anxiety sensitivity on the response to hyperventilation in college students with and without a history of spontaneous panic attacks. Reiss et al.'s (Behav. Res. Ther. 24, 1-8, 1986) Anxiety Sensitivity Index and Norton et al.'s (Behav. Ther. 17, 239-252, 1986) Panic Attack Questionnaire were used to select Ss. Following five min of voluntary hyperventilation, high anxiety sensitivity Ss reported more anxiety and more hyperventilation sensations than did low anxiety sensitivity Ss. A history of panic was only associated with enhanced responding to hyperventilation in Ss with high anxiety sensitivity; low anxiety sensitivity Ss who had experience with panic were no more responsive than low anxiety sensitivity Ss who had never had a panic attack. These findings suggest that high anxiety sensitivity may be a crucial determinant of panic attacks provoked by biological challenges (e.g. hyperventilation, sodium lactate infusion).     

Panic disorder: A product of classical conditioning

Contrary to the common view that all panic attacks have a single etiology, it is shown that a distinction must be made between initial attacks, for which there are many causes, and recurrent attacks (panic disorder) which have a common basis. Most initial panic attacks are attributable to the physiological effects of hyperventilation resulting from severe and prolonged anxiety. It has been claimed that the attacks are due to such symptoms as dyspnea, tachycardia and dizziness being misattributed to deadly illness or incipient insanity. We reject this view on several grounds, and in particular because of a pilot study that showed that such attributions follow the onset of panic. Apart from some biological cases, the common initial panic is an unconditioned response to a bizarre stimulus complex produced by excessive hyperventilation, and panic disorder is the result of contiguous stimuli, especially endogenous stimuli, being conditioned to the elicited anxiety. Treatment accords with principles of conditioning.     

Increased cardiac awareness in panic disorder.

We investigated cardiac perception in panic disorder with both self-report and objective measures. In Study 1, 120 patients with panic disorder, 86 infrequent panickers, and 38 patients with other anxiety disorders reported greater cardiac and gastrointestinal awareness than 62 normal control subjects. Subjects with panic attacks reported greater cardiac awareness, but not gastrointestinal awareness, than those with other anxiety disorders. Studies 2 and 3 included a test of heart rate perception in which subjects silently counted their heart-beats without taking their pulse. In Study 2, 65 panic disorder patients showed better performance than 50 infrequent panickers, 27 patients with simple phobias, and 46 normal control subjects. No group differences were found in ability to estimate time intervals. In Study 3, 13 patients with panic disorder and 15 with generalized anxiety disorder showed better heart rate perception than 16 depressed patients.     

The role of anxiety sensitivity and lack of emotional approach coping in depressive symptom severity among a non-clinical sample of uncued panickers

Panic attacks and depression frequently co-occur, and the presence of this co-morbidity is often associated with worse outcomes compared with each disorder alone. Despite this, not everyone who experiences panic attacks also suffers from depression, suggesting that individual difference factors may play a role in this co-morbidity. The purpose of this study was to provide a preliminary investigation of two such individual difference factors, examining the role of anxiety sensitivity and lack of emotional approach coping in depressive symptom severity among a non-clinical sample of uncued panickers. A sample of 79 college students reporting the occurrence of uncued panic attacks within the past year completed a series of questionnaires assessing the lower-order factors of anxiety sensitivity, emotional approach coping, panic attack frequency, panic-related disability, panic symptom severity and depressive symptom severity. Participants with more severe depressive symptoms reported greater anxiety sensitivity, panic attack frequency, panic symptom severity, panic-related disability and lack of emotional approach coping. The particular anxiety sensitivity dimension of fear of cognitive dyscontrol and lack of emotional approach coping emerged as the best predictors of depressive symptom severity. Findings are discussed in terms of their implications for the improved understanding of this co-morbidity, as well as its treatment.     

Waning of panic sensations during prolonged hyperventilation

Recent theories about panic emphasize that a hyperventilatory positive feedback loop is involved in panic: catastrophic misinterpretation of bodily sensations may trigger anxiety, anxiety may stimulate hyperventilation, hyperventilation may promote the salience of feared sensations etc. Such models leave unexplained how and when panics come to an end. It was hypothesised that panic with hyperventilation may end because pronounced hyperventilation becomes, in the course of time, less powerful in generating perceivable bodily sensations. Twenty healthy subjects hyperventilated forcefully and experienced clear panic symptoms as defined by DSM IIIR. When pCO2 was kept 55% below base line for 90 min, panic symptoms waned. The mean intensity of the symptoms declined as did the number of symptoms occurring. No panic symptoms were observed in the control group (n = 20) who ventilated normally. In so far as hyperventilation is involved in the positive feedback loops that characterize panic, panic attacks may be time-limited because sensations induced by hyperventilation become less salient even if massive hyperventilation continues. As to the explanation of the reported phenomenon, it is suggested that, apart from habituation, local physiological changes due to prolonged hyperventilation may produce a decrease in interoceptive input.     

Book Reviews

Panic attacks and depression frequently co‐occur, and the presence of this co‐morbidity is often associated with worse outcomes compared with each disorder alone. Despite this, not everyone who experiences panic attacks also suffers from depression, suggesting that individual difference factors may play a role in this co‐morbidity. The purpose of this study was to provide a preliminary investigation of two such individual difference factors, examining the role of anxiety sensitivity and lack of emotional approach coping in depressive symptom severity among a non‐clinical sample of uncued panickers. A sample of 79 college students reporting the occurrence of uncued panic attacks within the past year completed a series of questionnaires assessing the lower‐order factors of anxiety sensitivity, emotional approach coping, panic attack frequency, panic‐related disability, panic symptom severity and depressive symptom severity. Participants with more severe depressive symptoms reported greater anxiety sensitivity, panic attack frequency, panic symptom severity, panic‐related disability and lack of emotional approach coping. The particular anxiety sensitivity dimension of fear of cognitive dyscontrol and lack of emotional approach coping emerged as the best predictors of depressive symptom severity. Findings are discussed in terms of their implications for the improved understanding of this co‐morbidity, as well as its treatment.     

Provocation of panic: three elements of the panic reaction in four anxiety disorders

Subjects with agoraphobia (N = 25), panic disorder (N = 25), social phobia (N = 19) or generalized anxiety disorder (N = 10) and controls with no psychiatric history (N = 16) underwent two provocation tests, voluntary hyperventilation and inhalation of 5% CO2 in air, and three experimental control conditions. They were measured on three elements of the panic reaction: somatic symptoms, psychic anxiety and fears of impending doom, and on a standard YES/NO measure of panic attack. The provocation conditions produced increased somatic symptoms and psychic anxiety across all groups relative to the control conditions. The agoraphobic and panic disorder groups showed a significantly greater increase in fears of impending doom from control to provocation conditions than the social phobic and GAD patients. This difference was not observed on measures of somatic symptoms or psychic anxiety. The present results provide some support for the theory that panic attacks result from the catastrophic misinterpretation of anxious symptoms, in this case produced by the two provocation tests.     

The hyperventilation syndrome in panic disorder, agoraphobia and generalized anxiety disorder

The symptom complex of panic disorder and generalized anxiety disorder suggests an etiological role for hyperventilation. The present study investigates the overlap between DSM-III-R panic disorder, panic disorder with agoraphobia and generalized anxiety disorder with hyperventilation syndrome (HVS). The anxiety disorder diagnoses were based on a structured interview, and HVS syndrome (HVS). The anxiety disorder diagnoses were based on a structured interview, and HVS determined by the so-called hyperventilation provocation test (a brief period of voluntary hyperventilation with recognition of symptoms). The overlap rates with HVS were: 48% for panic disorder, 83% for panic disorder with agoraphobia and 82% for generalized anxiety disorder. However, a pilot study on transcutaneous monitoring of carbon dioxide tension leads us to question the validity of the voluntary hyperventilation method that we used to determine HVS-status. It is unclear whether hyperventilation plays an important role in panic and general anxiety, as our overlap findings suggest. For patients who recognize the symptoms induced by voluntary hyperventilation, the hyperventilation provocation procedure provides a therapeutic means of exposure to feared bodily sensations.     

The effects of voluntary hyperventilation on patients with chest pain without coronary artery disease

The present investigation was designed to examine panic symptom experience in patients with chest pain of nonorganic etiology, using a hyperventilation provocation procedure. Given the recent focus on panic disorder in patients with nonorganic chest pain, we assessed three indices of physiological arousal, subjective anxiety, and endorsement of DSM-III-R panic symptomatology in response to 3 min of voluntary hyperventilation. Subjects included 23 patients with nonorganic chest pain (CP sample) and matched normal controls (NC sample). The results indicate that hyperventilation produced significant increases in skin conductance, heart rate, and upper trapezious EMG in both CP and NC samples. Despite equivalent levels of physiological arousal and subjective anxiety, the CP sample endorsed a greater number of DSM-III-R panic symptoms relative to the NC sample. Examination of post-hyperventilation symptoms indicated that a greater percentage of the CP sample reported palpitations, nausea, and chest pain when compared with normals. Comparison of CP patients with and without Panic Disorder revealed no significant differences on any measure. The results suggests that hyperventilation plays a role in symptom experience in patients with nonorganic chest pain, although anxiety does not appear central in moderating this effect.     

Differences in reported symptom profile between panic disorder and other DSM-III-R anxiety disorders.

Previous research has indicated that reports of panic attacks are associated with a different set of symptoms to reports of generalized anxiety. The present two studies attempted to extend these findings to specific (situational) fears. In Study 1, 55 subjects with panic disorder were compared on their symptom profile during their panic attacks to 65 subjects with other anxiety disorders [simple phobia, social phobia and obsessive-compulsive disorder (OCD)] during response to their feared cue. The results indicated that, compared to subjects with other anxiety disorders, subjects with panic disorder were more likely to report parasthesias, dizziness, faintness, unreality, dyspnea, fear of dying and fear of going crazy/losing control. In Study 2, 90 subjects meeting diagnostic criteria for both panic disorder and another anxiety disorder (simple phobia, social phobia or OCD) were compared on the symptoms experienced during their unexpected panic attacks and their situationally-triggered fears respectively. Combining the symptoms found in Study 1 to differ between the groups into a linear combination, there was a significant interaction found between the type of fear reaction (panic attack vs cued fear response) and symptom group. Taken together, these findings suggest that reports of unexpected panic attacks associated with panic disorder are characterized by a different symptom profile to reports of specific fear reactions that are part of a phobic disorder or OCD.     

Animal phobias versus claustrophobias: Exteroceptive versus interoceptive cues

The overall purpose of this investigation was to examine heterogeneity among specific phobias. In particular, the goals were to compare features of fear responding between individuals fearful of claustrophobic situations and individuals fearful of spiders/snakes, and to compare their response to hyperventilation challenges. By so doing, specific predictions were tested in relation to a conceptual model of exteroceptive and interoceptive fear cues. Using a nonclinical sample, 19 subjects with spider/snake phobias, 18 nonphobies, and 9 subjects with claustrophobias were exposed on two separate occasions to a live tarantula or python, a small closet, and a hyperventilation challenge. Dependent measures included subjective anxiety, panic attacks, physical symptoms, cognitive symptoms (or, fear of symptoms) and heart rate. In addition, subjects completed a standardized self-report scale that measures fear of bodily symptoms of arousal. It was found that subjects with claustrophobia reported more physical symptoms and cognitive symptoms than did subjects with snake/spider phobias, in response to their fear-relevant stimulus. In addition, claustrophobic subjects were more fearful of hyperventilation challenges and reported more fear of bodily symptoms, than did snake/spider phobic subjects. Finally, subjects with claustrophobia were as fearful of hyperventilation as they were of their fear-relevant stimulus. Theoretical and empirical implications of these findings are discussed.     

Physiological and psychological reactivity in women with asthma: the effects of anxiety and menstrual cycle phase.

The relation between menstrual cycle timing, panic attacks, and diagnosis of asthma was explored in this study. Women with or without asthma and with or without a history of panic attacks engaged in a psychophysiological task during either the intermenstrual or premenstrual cycle phase and completed self-report measures of menstrual symptoms and attitudes, general psychological symptoms, and attitudes toward illness. No significant differences were identified for psychological or psychophysiological measures with menstrual cycle phase as a factor. However, women with both asthma and a history of panic attacks reported more general psychological distress than women in the other groups, and more state anxiety than controls. Women in the asthma, asthma and panic, and panic groups reported higher anxiety sensitivity than the control group. After listening to asthma-related scenes, women with asthma exhibited a decrease in peak expiratory air flow, and women with asthma and panic exhibited increased skin conductance response magnitude. Implications for the role of anxiety in lung function are discussed, as well as directions for future research with asthma and anxiety populations.     

Interoceptive accuracy and panic

Psychophysiological models of panic hypothesize that panickers focus attention on and become anxious about the physical sensations associated with panic. Attention on internal somatic cues has been labeled interoception. The present study examined the role of physiological arousal and subjective anxiety on interoceptive accuracy. Infrequent panickers and nonanxious participants participated in an initial baseline to examine overall interoceptive accuracy. Next, participants ingested caffeine, about which they received either safety or no safety information. Using a mental heartbeat tracking paradigm, participants' count of their heartbeats during specific time intervals were coded based on polygraph measures. Infrequent panickers were more accurate in the perception of their heartbeats than nonanxious participants. Changes in physiological arousal were not associated with increased accuracy on the heartbeat perception task. However, higher levels of self-reported anxiety were associated with superior performance.     

Selective Processing of Threat Cues in Subjects with Panic Attacks

Abstract

Previous research has demonstrated that patients with generalised anxiety disorder, phobias, and obsessive-compulsive disorder show an attentional bias towards threat cues related to their respective disorders. Two studies are presented that used a modified Stroop colour naming task to assess attentional bias in subjects with panic attacks. In Study 1, 24 panic disorder patients and 24 normal controls were presented three cards containing threat words related to physical harm, separation, or social embarrassment. Colour naming times were compared between these cards and control cards containing matched non-threat words. Reaction time differences in the two groups were in opposite directions, patients tending to be slower in colour naming threat words, and controls, faster. In Study 2, 18 non-clinical panickers and 18 controls were presented cards containing physical threat words, neutral control words, or colour words, respectively. Panickers showed greater interference than controls in colour naming threat words but not in colour naming colour words. The results are consistent with an attentional bias for threat-related material in subjects with panic attacks. Implications for psychophysiological models of 'spontaneous' panic attacks are discussed.     

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

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