Clinical features of respiratory and nocturnal panic disorder subtypes

Disruption of estradiol regulation of orexin neurons: a novel mechanism in excessive ventilatory response to CO2 inhalation in a female rat model of panic disorder

Panic disorder (PD) is ~2 times more frequent in women. An excessive ventilatory response to CO2 inhalation is more likely during the premenstrual phase. While ovarian hormones appear important in the pathophysiology of PD, their role remains poorly understood as female animals are rarely used in pre-clinical studies. Using neonatal maternal separation (NMS) to induce a "PD-like" respiratory phenotype, we tested the hypothesis that NMS disrupts hormonal regulation of the ventilatory response to CO2 in female rats. We then determined whether NMS attenuates the inhibitory actions of 17-β estradiol (E2) on orexin neurons (ORX). Pups were exposed to NMS (3 h/day; postnatal day 3-12). The ventilatory response to CO2-inhalation was tested before puberty, across the estrus cycle, and following ovariectomy. Plasma E2 and hypothalamic ORXA were measured. The effect of an ORX1 antagonist (SB334867; 15 mg/kg) on the CO2 response was tested. Excitatory postsynaptic currents (EPSCs) were recorded from ORX neurons using whole-cell patch-clamp. NMS-related increase in the CO2 response was observed only when ovaries were functional; the largest ventilation was observed during proestrus. SB334867 blocked this effect. NMS augmented levels of ORXA in hypothalamus extracts. EPSC frequency varied according to basal plasma E2 levels across the estrus cycle in controls but not NMS. NMS reproduces developmental and cyclic changes of respiratory manifestations of PD. NMS disrupts the inhibitory actions of E2 on the respiratory network. Impaired E2-related inhibition of ORX neurons during proestrus is a novel mechanism in respiratory manifestations of PD in females.

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.

Clinical characteristics of the respiratory subtype in panic disorder patients

OBJECTIVE

Panic disorder has been suggested to be divided into the respiratory and non-respiratory subtypes in terms of its clinical presentations. The present study aimed to investigate whether there are any differences in treatment response and clinical characteristics between the respiratory and non-respiratory subtypes of panic disorder patients.

METHODS

Among the 48 patients those who completed the study, 25 panic disorder patients were classified as the respiratory subtype, whereas 23 panic disorder patients were classified as the non-respiratory subtype. All patients were treated with escitalopram or paroxetine for 12 weeks. We measured clinical and psychological characteristics before and after pharmacotherapy using the Panic Disorder Severity Scale (PDSS), Albany Panic and Phobic Questionnaire (APPQ), Anxiety Sensitivity Index-Revised (ASI-R), State-Trait Anxiety Inventory (STAI-T, STAI-S), Hamilton Anxiety Rating Scale (HAM-A), and Hamilton Depression Rating Scale (HAM-D).

RESULTS

The prevalence of the agoraphobia was significantly higher in the respiratory group than the non-respiratory group although there were no differences in gender and medication between the two groups. The respiratory group showed higher scores on the fear of respiratory symptoms of the ASI-R. In addition, after pharmacotherapy, the respiratory group showed more improvement in panic symptoms than the non-respiratory group.

CONCLUSION

Panic disorder patients with the respiratory subtype showed more severe clinical presentations, but a greater treatment response to SSRIs than those with non-respiratory subtype. Thus, classification of panic disorder patients as respiratory and non-respiratory subtypes may be useful to predict clinical course and treatment response to SSRIs.

Myocardial perfusion imaging study of CO(2)-induced panic attack

Chest pain is often seen alongside with panic attacks. Moreover, panic disorder has been suggested as a risk factor for cardiovascular disease and even a trigger for acute coronary syndrome. Patients with coronary artery disease may have myocardial ischemia in response to mental stress, in which panic attack is a strong component, by an increase in coronary vasomotor tone or sympathetic hyperactivity setting off an increase in myocardial oxygen consumption. Indeed, coronary artery spasm was presumed to be present in cases of cardiac ischemia linked to panic disorder. These findings correlating panic disorder with coronary artery disease lead us to raise questions about the favorable prognosis of chest pain in panic attack. To investigate whether myocardial ischemia is the genesis of chest pain in panic attacks, we developed a myocardial perfusion study through research by myocardial scintigraphy in patients with panic attacks induced in the laboratory by inhalation of 35% carbon dioxide. In conclusion, from the data obtained, some hypotheses are discussed from the viewpoint of endothelial dysfunction and microvascular disease present in mental stress response.

Efficacy of Two Cognitive-Behavioral Treatment Modalities for Panic Disorder With Nocturnal Panic Attacks

The aim of this research was to examine the efficacy of two cognitive-behavioral treatment modalities for panic disorder (PD) with nocturnal panic (NP). The first study was conducted to determine whether conventional CBT for PD was effective for PD with NP in three participants. A second study sought to explore whether a CBT adapted to NP would lead to different clinical outcomes in three other participants. A multiple-baseline single-case design across individuals was used in both studies. Treatment outcome was assessed with standardized clinician ratings, self-report questionnaires, and daily self-monitoring. Results revealed that both the conventional and the adapted treatments showed a faster decrease in NPs versus daytime panics and significant clinical changes in all measures for up to a year after therapy. Hence, the changes brought about by the adapted treatment seemed to be similar to those obtained using conventional treatment. In light of these results, it can be presumed that conventional strategies may be sufficient for the treatment of NP. These observations raise questions regarding the real need to adapt treatments specifically to NP.

Obstructive sleep apnea and severe mental illness: evolution and consequences

Sleep complaints are commonly encountered in psychiatric clinics. Underlying medical disorders or sleep disorders need to be identified and treated to optimize treatment of the mental illness. Excessive daytime sleepiness, which is the main symptom of obstructive sleep apnea (OSA), overlaps with those of many severe mental illnesses. Medication side effects or the disorder itself maybe account for daytime sleepiness but comorbid OSA is a possibility that should not be overlooked. The diagnosis of OSA is straightforward but treatment compliance is problematic in psychiatric patients. This article summarizes studies concerning comorbid OSA in patients with severe mental illness and includes suggestions for future investigations.

Panic attack triggering myocardial ischemia documented by myocardial perfusion imaging study. A case report

BACKGROUND

Chest pain, a key element in the investigation of coronary artery disease is often regarded as a benign prognosis when present in panic attacks. However, panic disorder has been suggested as an independent risk factor for long-term prognosis of cardiovascular diseases and a trigger of acute myocardial infarction.

OBJECTIVE

Faced with the extreme importance in differentiate from ischemic to non-ischemic chest pain, we report a case of panic attack induced by inhalation of 35% carbon dioxide triggering myocardial ischemia, documented by myocardial perfusion imaging study.

DISCUSSION

Panic attack is undoubtedly a strong component of mental stress. Patients with coronary artery disease may present myocardial ischemia in mental stress response by two ways: an increase in coronary vasomotor tone or a sympathetic hyperactivity leading to a rise in myocardial oxygen consumption. Coronary artery spasm was presumed to be present in cases of cardiac ischemia linked to panic disorder. Possibly the carbon dioxide challenge test could trigger myocardial ischemia by the same mechanisms.

CONCLUSION

The use of mental stress has been suggested as an alternative method for myocardial ischemia investigation. Based on translational medicine objectives the use of CO2 challenge followed by Sestamibi SPECT could be a useful method to allow improved application of research-based knowledge to the medical field, specifically at the interface of PD and cardiovascular disease.

Prevalence and correlates of respiratory and non-respiratory panic attacks in the general population

BACKGROUND

Panic attacks are heterogeneous with regards to symptom profile. Subtypes of panic attacks have been proposed, of which the most investigated is respiratory panic attacks (RPA). Limited information exists about RPA in the general population.

METHOD

The prevalence and correlates of RPA and non-respiratory panic attacks (NRPA) were examined in a subsample (n=8.796) of individuals participating in a cross-sectional survey of the adult general population of six European countries. Panic attacks, mental disorders, and chronic physical conditions were assessed with the Composite International Diagnostic Interview (CIDI) 3.0. Data on use of health services and disability were obtained.

RESULTS

The lifetime prevalence of RPA was 6.77 and the 12-month prevalence was 2.26. No robust associations of RPA with sociodemographic characteristics, mental disorders or physical conditions were found as compared to NRPA. RPA were associated with increased use of health services but similar disability in comparison to NRPA.

LIMITATIONS

Few direct data are available on the validity of the CIDI to assess RPA. Other definitions of RPA exist in the literature.

CONCLUSIONS

Our findings suggest that there are very few differences between RPA and NRPA and do not support the need of subtyping panic attacks in current classification systems.

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.

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.

Panic disorder respiratory subtype: a comparison between responses to hyperventilation and CO2 challenge tests

In this study 117 panic disorder patients were divided into a respiratory subtype group and a non-respiratory subtype group. The respiratory subtype patients were observed to be more sensitive to the 35% CO(2) inhalation challenge test and the hyperventilation test than the non-respiratory subtype patients.