Panic disorder: from respiration to the homeostatic brain

A pontomesencephalic PACAPergic pathway underlying panic-like behavioral and somatic symptoms in mice

Panic disorder is characterized by uncontrollable fear accompanied by somatic symptoms that distinguish it from other anxiety disorders. Neural mechanisms underlying these unique symptoms are not completely understood. Here, we report that the pituitary adenylate cyclase-activating polypeptide (PACAP)-expressing neurons in the lateral parabrachial nucleus projecting to the dorsal raphe are crucial for panic-like behavioral and physiological alterations. These neurons are activated by panicogenic stimuli but inhibited in conditioned fear and anxiogenic conditions. Activating these neurons elicits strong defensive behaviors and rapid cardiorespiratory increase without creating aversive memory, whereas inhibiting them attenuates panic-associated symptoms. Chemogenetic or pharmacological inhibition of downstream PACAP receptor-expressing dorsal raphe neurons abolishes panic-like symptoms. The pontomesencephalic PACAPergic pathway is therefore a likely mediator of panicogenesis, and may be a promising therapeutic target for treating panic disorder.

The efficacy, safety, and adverse events of azapirones in anxiety disorders: A systematic review and meta-analysis of randomized controlled trials

Azapirones have been proposed as anxiety and mood modulators. We assessed azapirones' viability in anxiety disorders via systematic review and random-effects meta-analysis, inquiring PubMed/MEDLINE/CENTRAL/WHO-ICTRP/WebOfScience/VIP up-to 05/01/2023. We conducted sensitivity, and subgroup analyses assessing heterogeneity, publication bias, risk of bias, and confidence in the evidence within the GRADE framework. Symptom reduction (mean difference/MD), study-defined response (risk ratios/RRs), and acceptability were co-primary outcomes. Adverse events and withdrawal were secondary. Seventy studies were included. In generalized anxiety disorder (GAD), azapirones largely outperformed placebo (MD=-4.91, 95%C.I.[-5.91, -3.90], Hedges'g -1.37 [-1.02, -0.73]), k = 22, n = 2,567; RR=1.64, 95%C.I.[1.45, 1.86], k = 9, n = 1,346). While azapirones overlapped benzodiazepines in symptom reduction (MD=-0.12, 95%C.I.[-0.70, 0.45], k = 34, n = 3,160), they were slightly outperformed in response rate (RR=0.94, 95%C.I.[0.90, 0.99], k = 18, n = 2,423). Azapirones overlapped SRIs (MD=0.09, 95%C.I.[-0.49, 0.67], k = 8, n = 747; RR=0.97, 95%C.I.[0.89, 1.07], k = 7, n = 737). Confidence in estimates was high/moderate vs. placebo, moderate/low vs. benzodiazepine, very-low vs. SRIs. Azapirones failed to outperform the placebo in panic and social anxiety disorders. Azapirones overlapped placebo and SRIs in drop-out rates, while they showed higher treatment discontinuation rates than benzodiazepines (RR=1.33, 95%C.I.[1.16, 1.53], k = 23, n = 2,768). Azapirones caused less sedation/fatigue/drowsiness/weakness/cognitive issues than benzodiazepines, resembling placebo. They caused more nausea and dizziness than placebo, more headache and nausea than benzodiazepines, and less nausea and xerostomia than SRIs. Azapirones proved effective and relatively well-tolerated for GAD. They should be preferred over benzodiazepines, especially in the long-term, considering their lower sedation and addiction potential, representing a potential SRI alternative. Further research is warranted to prove efficacy in panic and social anxiety.

The relationship between psychological conditions and recurrence of benign paroxysmal positional vertigo: a retrospective cohort study

BACKGROUND

Psychological conditions have been found to be associated with an increased risk of incident benign paroxysmal positional vertigo (BPPV). However, much less is known on whether and how psychological conditions such as anxiety, insomnia and obsessive-compulsive disorder (OCD) affect the recurrence of BPPV.

METHODS

A retrospective cohort study of 2,612 outpatients and inpatients diagnosed with BPPV between September 2012 and August 2020. BPPV recurrence was followed up until February 2021. The Cox proportional hazard regression was used to analyze the association between psychological conditions and the risk of the first recurrence. Poisson regression was applied to analyze the association between psychological conditions and the number of recurrences in patients with at least one relapse.

RESULTS

During the follow-up, 391 patients had at least one BPPV recurrence. Female BPPV patients were more likely than male patients to experience relapses than male patients, but the characteristics of BPPV recurrence (number of recurrences and duration between recurrences) did not differ between men and women. After adjustment for sex, age and comorbidities, a heightened risk of first BPPV recurrence was found to be associated with anxiety (hazard ratio [HR]: 1.30, 95% confidence interval [CI]: 1.01, 1.68) and OCD (HR: 2.15, 95% CI: 1.31, 3.52). An increased risk of first BPPV recurrence associated with insomnia was only observed in male patients (HR: 2.22, 95% CI: 1.24, 3.98) but not in female patients (HR: 0.91, 95% CI: 0.63, 1.31). None of these psychological conditions were associated with the number of recurrences in patients who experienced recurrence.

CONCLUSIONS

The presence of anxiety and OCD increased the risk of first BPPV recurrence, as well as insomnia for male patients. These psychological conditions were not associated with the number of BPPV recurrences. Diagnosis and treatment of these psychological conditions could be a useful strategy to prevent the recurrence of BPPV.

Diagnostic delay of oral squamous cell carcinoma and the fear of diagnosis: A scoping review

The mortality rate of patients affected with oral squamous cell carcinoma (OSCC) has been stable in recent decades due to several factors, especially diagnostic delay, which is often associated with a late stage diagnosis and poor prognosis. The aims of this paper were to: analyze diagnostic delay in OSCC and to discuss the various psychological factors of patients with OSCC, with particular attention to the patient's fear of receiving news regarding their health; and the professional dynamics related to the decision-making processes in cases of suspected OSCC. A preliminary review of literature focusing on OSCC diagnostic delay was performed. Seven articles were included with the diagnostic delay ranging from 45  days to approximately 6  months. Patients' fears and, to a lesser degree, the concerns of dentists, were found to be still poorly investigated. On the basis of the authors' professional experience, the development of oral lesions of unknown origin may generate different behaviors in the decision-making processes by patients and clinicians, and fear may play a key role in the distinct steps of this process. It is crucial to increase awareness and inform patients about the onset of OSCC, and contemporaneously encourage experimental studies on patients' fear and professional behaviors with respect to communication regarding OSCC.

Antipanic-like effect of esketamine and buprenorphine in rats exposed to acute hypoxia

The antidepressant effect of ketamine has been widely acknowledged and the use of one of its enantiomers, S-ketamine (esketamine), has recently been approved for the clinical management of treatment-resistant depression. As with ketamine, the non-selective opioid receptor-interacting drug buprenorphine is reported to have antidepressant and anxiolytic properties in humans and rodents. Given the fact that antidepressant drugs are also first line treatment for panic disorder, it is surprising that the potential panicolytic effect of these compounds has been scarcely (ketamine), or not yet (buprenorphine) investigated. We here evaluated the effects of ketamine (the racemic mixture), esketamine, and buprenorphine in male Wistar rats submitted to a panicogenic challenge: acute exposure to hypoxia (7% O₂). We observed that esketamine (20 mg/kg), but not ketamine, decreased the number of escape attempts made during hypoxia, and this effect could be observed even 7 days after the drug administration. A panicolytic-like effect was also observed with MK801, which like esketamine, antagonizes NMDA glutamate receptors. Buprenorphine (0.3 mg/kg) also impaired hypoxia-induced escape, an effect blocked by the non-selective opioid receptor antagonist naloxone, indicating an interaction with classical ligand sites, such as µ and kappa receptors, but not with nociception/orphanin FQ receptors. Altogether, the results suggest that esketamine and buprenorphine cause rapid-onset panicolytic-like effects, and may be alternatives for treating panic disorder, particularly in patients who are refractory to standard pharmacological treatment.

Experimental Drugs for Panic Disorder: An Updated Systematic Review

Several effective pharmacological therapies for panic disorder (PD) are available, but they have some drawbacks, and unsatisfactory outcomes can occur. Expanding the variety of anti-panic medications may allow for improving PD treatment. The authors performed an updated systematic review of preclinical and clinical (Phase I–III) pharmacological studies to look for advances made in the last six years concerning novel-mechanism-based anti-panic compounds or using medications approved for nonpsychiatric medical conditions to treat PD. The study included seven published articles presenting a series of preclinical studies, two Phase I clinical studies with orexin receptor (OXR) antagonists, and two clinical studies investigating the effects of D-cycloserine (DCS) and xenon gas in individuals with PD. The latest preclinical findings confirmed and expanded previous promising indications of OXR1 antagonists as novel-mechanism-based anti-panic compounds. Translating preclinical research into clinical applications remains in the early stages. However, limited clinical findings suggested the selective OXR1 antagonist JNJ-61393115 may exert anti-panic effects in humans. Overall, OXR1 antagonists displayed a favorable profile of short-term safety and tolerability. Very preliminary suggestions of possible anti-panic effects of xenon gas emerged but need confirmation with more rigorous methodology. DCS did not seem promising as an enhancer of cognitive-behavioral therapy in PD. Future studies, including objective panic-related physiological parameters, such as respiratory measures, and expanding the use of panic vulnerability biomarkers, such as hypersensitivity to CO₂ panic provocation, may allow for more reliable conclusions about the anti-panic properties of new compounds.

The Implications of the Diving Response in Reducing Panic Symptoms

Increased CO₂ sensitivity is common in panic disorder (PD) patients. Free divers who are known for their exceptional breathing control have lower CO₂ sensitivity due to training effects. This study aimed to investigate the immediate effects of cold facial immersion (CFI), breath holding and CO₂ challenges on panic symptoms. Healthy participants and patients with PD were subjected to four experimental conditions in a randomly assigned order. The four conditions were (a) breath-holding (BH), (b) CFI for 30 s, (c) CO₂ challenge, and (d) CO₂ challenge followed by CFI. Participants completed a battery of psychological measures, and physiological data (heart rate and respiration rate) were collected following each experimental condition. Participants with PD were unable to hold their breath for as long as normal controls; however, this finding was not significant, potentially due to a small sample size. Significant reductions in both physiological and cognitive symptoms of panic were noted in the clinical group following the CFI task. As hypothesized, the CFI task exerted demonstrable anxiolytic effects in the clinical group in this study by reducing heart rate significantly and lessening self-reported symptoms of anxiety and panic. This outcome demonstrates the promise of the CFI task for clinical applications.

Take my breath away: Neural activation at breath-hold differentiates individuals with panic disorder from healthy controls

There is neuroanatomical evidence of an "extended fear network" of brain structures involved in the etiology of panic disorder (PD). Although ventilatory distrubance is a primary symptom of PD these sensations may also trigger onset of a panic attack (PA). Here, a voluntary breath-holding paradigm was used to mimic the hypercapnia state in order to compare blood oxygen level-dependent (BOLD) response, at the peak of a series of 18 s breath-holds, of 21 individuals with PD to 21 low anxiety matched controls. Compared to the rest condition, BOLD activity at the peak (12 - 18 s) of the breath-hold was greater for PD versus controls within a number of structures implicated in the extended fear network, including hippocampus, thalamus, and brainstem. Activation was also observed in cortical structures that are shown to be involved in interoceptive and self-referential processing, such as right insula, middle frontal gyrus, and precuneus/posterior cingulate. In lieu of amygdala activation, our findings show elevated activity throughout an extended network of cortical and subcortical structures involved in contextual, interoceptive and self-referential processing when individuals with PD engage in voluntary breath-holding.

Nitric oxide in the dorsal periaqueductal gray mediates the panic-like escape response evoked by exposure to hypoxia

Exposure of rats to an environment with low O₂ levels evokes a panic-like escape behavior and recruits the dorsal periaqueductal gray (dPAG), which is considered to be a key region in the pathophysiology of panic disorder. The neurochemical basis of this response is, however, currently unknown. We here investigated the role played by nitric oxide (NO) within the dPAG in mediation of the escape reaction induced by hypoxia exposure. The results showed that exposure of male Wistar rats to 7% O₂ increased nitrite levels, a NO metabolite, in the dPAG but not in the amygdala or hypothalamus. Nitrite levels in the dPAG were correlated with the number of escape attempts during the hypoxia challenge. Injections of the NO synthesis inhibitor NPA, the NO-scavenger c- PTIO, or the NMDA receptor antagonist AP-7 into the dorsolateral column of the periaqueductal gray (dlPAG) inhibited escape expression during hypoxia, without affecting the rats' locomotion. Intra-dlPAG administration of c-PTIO had no effect on the escape response evoked by the elevated-T maze, a defensive behavior that has also been associated with panic attacks. Altogether, our results suggest that NO plays a critical role in mediation of the panic-like defensive response evoked by exposure to low O₂ concentrations.

Biological and Clinical Markers in Panic Disorder

OBJECTIVE

Classifying mental disorders on the basis of objective makers might clarify their aetiology, help in making the diagnosis, identify "at risk" individuals, determine the severity of mental illness, and predict the course of the disorder. This study aims to review biological and clinical markers of panic disorder (PD).

METHODS

A computerized search was carried out in PubMed and Science Direct using the key words: "marker/biomarker/clinical marker/neurobiology/staging" combined using Boolean AND operator with "panic." In addition, the reference lists from existing reviews and from the articles retrieved were inspected. Only English language papers published in peer-reviewed journals were included.

RESULTS

Structural changes in the amygdala, hippocampus, cerebral blood level in the left occipital cortex, serotonin 5-TH and noradrenergic systems activation, aberrant respiratory regulation, hearth rate variability, blood cells and peripheral blood stem cells, hypothalamic-pituitary-adrenal axis dysregulation were identified as potential candidate biomarkers of PD. Staging was identified as clinical marker of PD. According to the staging model, PD is described as follows: prodromal phase (stage 1); acute phase (stage 2); panic attacks (stage 3); chronic phase (stage 4).

CONCLUSION

The clinical utility, sensitivity, specificity, and the predictive value of biomarkers for PD is still questionable. The staging model of PD might be a valid susceptibility, diagnostic, prognostic, and predictive marker of PD. A possible longitudinal model of biological and clinical markers of PD is proposed.

Respiratory subtype of panic disorder: Can serum phosphate levels be a possible outcome to group cognitive-behavior therapy?

OBJECTIVE

Panic disorder (PD) respiratory subtype (RS) was described in order to cluster patients according to their symptoms. These patients are characterized by experiencing a relatively high number of noticeable respiratory symptoms during a panic attack (PA) and a higher reactivity to CO₂. In this study, we aimed to evaluate the clinical relevance of this diagnostic category, evaluating if there are different responses to cognitive-behavioral therapy in patients with panic disorder RS as compared to those with the non-respiratory subtype (NRS), using serum phosphate as a biological marker.

METHODS

Patients were assessed by a clinical interview followed by a structured diagnostic interview (M.I.N.I) and classified as RS or NRS based on symptoms. The severity of PD was evaluated throughout the PDSS, CGI, HAM-A, STAI and the BDI rating scales. All patients underwent 12 structured sessions of group-CBT for PD and had their blood collected at baseline and after treatment to assess phosphate levels.

RESULTS

One hundred and thirty-eight patients have been assessed, and 102 were included in this trial. Sixty-nine patients completed the treatment protocol, 42 were classified as RS and 27 as NRS. Both RS and NRS patients improved in all clinical scales (p < 0.001). The mean phosphate levels increased from 2.44 mg/dl ± 0.49 at baseline to 3.38 mg/dl ± 0.52 (p < 0.01) in the RS group as well as from 2.46 mg/dl ± 0.64 at baseline to 3.46 mg/dl ± 0.61 (p < 0.01) in the NSR group.

LIMITATIONS

Small sample size and the lack of assessment of other clinical and physiological parameters, such as respiratory variables.

CONCLUSION

Our findings suggest that both RS and NRS benefit from group CBT and that there was a change in phosphate levels after effective treatment in both groups. Our data support the idea that there is a reversal of the conditions that promote hypophosphatemia as chronic hyperventilation after CBT treatment, whereas it is in disagreement to the presence of two different PD subtypes based on phosphate levels once their rates did not differ at baseline and had a similar increase after effective treatment.

A randomized placebo-controlled trial of paroxetine for the management of anxiety in chronic obstructive pulmonary disease (PAC Study)

BACKGROUND

Despite the high prevalence of anxiety in COPD patients and its impact on quality of life, evidence to support the effectiveness of various anxiety treatment options is insufficient, leading to the need for further research in this field.

AIM

The aim of this study was to assess the efficacy and safety of paroxetine for the management of anxiety in COPD and the impact of treatment on patients' quality of life and rate of hospitalization.

PATIENTS AND METHODS

In a double-blind, randomized, controlled trial, COPD patients were allocated into groups that either received paroxetine 20 mg or placebo pills daily, for four months. Differences in outcomes were assessed based on an intention-to-treat analysis using linear mixed effects models. A chi-square test was used to compare the number of COPD-related admissions.

RESULTS

Thirty-eight participants were recruited. Twenty-two of these completed the trial. A clinically and statistically significant reduction was noted in anxiety symptoms after four months of treatment compared to the placebo. Clinically important improvement was noted in depression symptoms, with no statistically significant differences in walking distance or quality-of-life measure outcomes. The intervention group had less COPD-related admissions compared to the placebo group but experienced medication-related side effects.

CONCLUSION

Treatment with paroxetine significantly improved anxiety levels, but this difference did not translate into improved quality of life at four months follow-up.

Is panic disorder a disorder of physical fitness? A heuristic proposal

Currently, panic disorder (PD) is considered a mental disorder based on the assumptions that panic attacks (PAs) are “false alarms” that arise from abnormally sensitive defense systems in the central nervous system and that PD is treated with therapies specifically acting on anxiety or fear mechanisms. This article aims to propose an alternative perspective based on the results of some experimental studies. Our heuristic proposal suggests not only that PD may be a mental disorder but also that patients with PD have real abnormal body functioning, mainly involving cardiorespiratory and balance systems, leading to a decline in global physical fitness. PAs, as well as physical symptoms or discomfort in some environmental situations, may be “real alarms” signaling that the adaptability resources of an organism are insufficient to respond appropriately to some internal or external changes, thus representing the transient conscious awareness of an imbalance in body functioning. The antipanic properties of several modern treatments for PD may include their beneficial effects on body functions. Although anxiety or fear mechanisms are evidently involved in PD, we hypothesize that a reduction of physical fitness is the “primum movens” of PD, while anxiety or fear is induced and sustained by repeated signals of impaired body functioning. We propose considering panic in a broader perspective that offers a central role to the body and to contemplate the possible role of somatic treatments in PD.

Anxiety, Mood, and Personality Disorders in Patients with Benign Paroxysmal Positional Vertigo

INTRODUCTION

This study presents the current prevalence of anxiety, mood, and personality disorders as well as factors associated with the existence of psychiatric disorders in patients with benign paroxysmal positional vertigo (BPPV).

METHODS

The study sample comprised 46 patients with BPPV and 74 control subjects. Anxiety and mood disorders were ascertained via the Structured Clinical Interview for the Diagnostic and Statistical Manual (DSM) of Mental Disorders, Fourth Edition/Clinical Version. Personality disorders were diagnosed via the Structured Clinical Interview for DSM, Revised Third Edition, Personality Disorders.

RESULTS

Of the 46 patients, 18 (39.1%) had at least one mood or anxiety disorder and 13 (28.3%) had at least one personality disorder. The most common Axis I and Axis II disorders in the patient group were major depression in 8 (17.4%) and obsessive-compulsive personality disorder in 10 (21.7%) patients, respectively. It was found that major depression (p=0.021), generalized anxiety disorder (p=0.026) and obsessive- compulsive personality disorder (p=0.001) were more prevalent in the BPPV group compared with the control group.

CONCLUSION

Results suggest that psychiatric disturbances should be carefully checked in patients with BPPV due to the relatively high rate of comorbidity.

Management of Treatment-Resistant Panic Disorder

PURPOSE OF REVIEW

Purpose of Review Management of treatment-resistant (TR) panic disorder (PD) is an unresolved issue. In this paper, we provide a brief summary of previous findings, an updated (2015-2017) systematic review of pharmacological/non-pharmacological studies, and our personal perspective on this topic.

RECENT FINDINGS

Recent Findings We found a very limited number of recent findings. Quetiapine extended-release augmentation has not been found to be beneficial, in comparison to placebo, in non-responders to previously recommended pharmacotherapy. In non-responders to cognitive behavioral therapy (CBT), switching to paroxetine/citalopram has been found to be more effective than continuing CBT. Acceptance and commitment therapy (ACT) has shown some improvement in patients' resistance to previous psychological/pharmacological interventions compared with a waiting-list condition.

SUMMARY

Summary Previous and recent findings regarding the treatment of TR PD suffer from several methodological limitations. Available studies provide insufficient evidence to support the use of medications alternative to the recommended medications; the efficacy of ACT needs confirmation with more rigorous methodology. Prolonged pharmacotherapy may produce significant improvement in patients with unsatisfactory response to short-term pharmacotherapy, while switching to pharmacotherapy may help non-responders to CBT. We discuss our personal perspective on the definition of "treatment resistance" as it relates to PD and provide personalized intervention strategies to increase favorable clinical outcomes based on our clinical expertise and review of experimental studies on the pathophysiology of PD.

Psychological therapies for the treatment of anxiety disorders in chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) (commonly referred to as chronic bronchitis and emphysema) is a chronic lung condition characterised by the inflammation of airways and irreversible destruction of pulmonary tissue leading to progressively worsening dyspnoea. It is a leading international cause of disability and death in adults. Evidence suggests that there is an increased prevalence of anxiety disorders in people with COPD. The severity of anxiety has been shown to correlate with the severity of COPD, however anxiety can occur with all stages of COPD severity. Coexisting anxiety and COPD contribute to poor health outcomes in terms of exercise tolerance, quality of life and COPD exacerbations. The evidence for treatment of anxiety disorders in this population is limited, with a paucity of evidence to support the efficacy of medication-only treatments. It is therefore important to evaluate psychological therapies for the alleviation of these symptoms in people with COPD.

OBJECTIVES

To assess the effects of psychological therapies for the treatment of anxiety disorders in people with chronic obstructive pulmonary disease.

SEARCH METHODS

We searched the specialised registers of two Cochrane Review Groups: Cochrane Common Mental Disorders (CCMD) and Cochrane Airways (CAG) (to 14 August 2015). The specialised registers include reports of relevant randomised controlled trials from The Cochrane Library, MEDLINE, Embase, and PsycINFO. We carried out complementary searches on PsycINFO and CENTRAL to ensure no studies had been missed. We applied no date or language restrictions.

SELECTION CRITERIA

We considered all randomised controlled trials (RCTs), cluster-randomised trials and cross-over trials of psychological therapies for people (aged over 40 years) with COPD and coexisting anxiety disorders (as confirmed by recognised diagnostic criteria or a validated measurement scale), where this was compared with either no intervention or education only. We included studies in which the psychological therapy was delivered in combination with another intervention (co-intervention) only if there was a comparison group that received the co-intervention alone.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened citations to identify studies for inclusion and extracted data into a pilot-tested standardised template. We resolved any conflicts that arose through discussion. We contacted authors of included studies to obtain missing or raw data. We performed meta-analyses using the fixed-effect model and, if we found substantial heterogeneity, we reanalysed the data using the random-effects model.

MAIN RESULTS

We identified three prospective RCTs for inclusion in this review (319 participants available to assess the primary outcome of anxiety). The studies included people from the outpatient setting, with the majority of participants being male. All three studies assessed psychological therapy (cognitive behavioural therapy) plus co-intervention versus co-intervention alone. We assessed the quality of evidence contributing to all outcomes as low due to small sample sizes and substantial heterogeneity in the analyses. Two of the three studies had prespecified protocols available for comparison between prespecified methodology and outcomes reported within the final publications.We observed some evidence of improvement in anxiety over 3 to 12 months, as measured by the Beck Anxiety Inventory (range from 0 to 63 points), with psychological therapies performing better than the co-intervention comparator arm (mean difference (MD) -4.41 points, 95% confidence interval (CI) -8.28 to -0.53; P = 0.03). There was however, substantial heterogeneity between the studies (I2 = 62%), which limited the ability to draw reliable conclusions. No adverse events were reported.

AUTHORS' CONCLUSIONS

We found only low-quality evidence for the efficacy of psychological therapies among people with COPD with anxiety. Based on the small number of included studies identified and the low quality of the evidence, it is difficult to draw any meaningful and reliable conclusions. No adverse events or harms of psychotherapy intervention were reported.A limitation of this review is that all three included studies recruited participants with both anxiety and depression, not just anxiety, which may confound the results. We downgraded the quality of evidence in the 'Summary of findings' table primarily due to the small sample size of included trials. Larger RCTs evaluating psychological interventions with a minimum 12-month follow-up period are needed to assess long-term efficacy.

Is There Room for Second-Generation Antipsychotics in the Pharmacotherapy of Panic Disorder? A Systematic Review Based on PRISMA Guidelines

A role for second-generation antipsychotics (SGAs) in the treatment of panic disorders (PD) has been proposed, but the actual usefulness of SGAs in this disorder is unclear. According to the PRISMA guidelines, we undertook an updated systematic review of all of the studies that have examined, in randomized controlled trials, the efficacy and tolerability of SGAs (as either monotherapy or augmentation) in the treatment of PD, with or without other comorbid psychiatric disorders. Studies until 31 December 2015 were identified through PubMed, PsycINFO, Embase, Cochrane Library and Clinical trials.gov. Among 210 studies, five were included (two involving patients with a principal diagnosis of PD and three involving patients with bipolar disorder with comorbid PD or generalized anxiety disorder). All were eight-week trials and involved treatments with quetiapine extended release, risperidone and ziprasidone. Overall, a general lack of efficacy of SGAs on panic symptoms was observed. Some preliminary indications of the antipanic effectiveness of risperidone are insufficient to support its use in PD, primarily due to major limitations of the study. However, several methodological limitations may have negatively affected all of these studies, decreasing the validity of the results and making it difficult to draw reliable conclusions. Except for ziprasidone, SGAs were well tolerated in these short-term trials.

Is there cardiac risk in panic disorder? An updated systematic review

BACKGROUND

The recognized relationship between panic disorder (PD) and cardiac disorders (CDs) is not unequivocal. We reviewed the association between PD and coronary artery disease (CAD), arrhythmias, cardiomyopathies, and sudden cardiac death.

METHODS

We undertook an updated systematic review, according to PRISMA guidelines. Relevant studies dating from January 1, 2000, to December 31, 2014, were identified using the PubMed database and a review of bibliographies. The psychiatric and cardiac diagnostic methodology used in each study was then to very selective inclusion criteria.

RESULTS

Of 3044 studies, 14 on CAD, 2 on cardiomyopathies, and 1 on arrhythmias were included. Overall, the studies supported a panic-CAD association. Furthermore, in some of the studies finding no association between current full-blown PD and CAD, a broader susceptibility to panic, manifesting as past PD, current agoraphobia, or subthreshold panic symptoms, appeared to be relevant to the development of CAD. Preliminary data indicated associations between panic, arrhythmias, and cardiomyopathies.

LIMITATIONS

The studies were largely cross-sectional and conducted in cardiological settings. Only a few included blind settings. The clinical conditions of patients with CDs and the qualifications of raters of psychiatric diagnoses were highly heterogeneous. CDs other than CAD had been insufficiently investigated.

CONCLUSIONS

Our review supported a relationship between PD and CDs. Given the available findings and the involvement of the cardiorespiratory system in the pathophysiology of PD, an in-depth investigation into the panic-CDs association is highly recommended. This should contribute to improved treatment and prevention of cardiac events and/or mortality, linked to PD.

Are respiratory abnormalities specific for panic disorder? A meta-analysis

OBJECTIVES

There is evidence of baseline respiratory abnormalities in panic disorder (PD), but whether they are specific to PD remains unclear. To investigate this issue, we meta-analyzed results from studies comparing baseline respiratory and hematic variables between subjects with PD and subjects with other anxiety disorders.

METHODS

A literature search in bibliographic databases was performed. Fixed-effects models were applied. Several moderator analyses and publication bias diagnostics were performed.

RESULTS

We found: (1) significantly lower mean end-tidal partial pressure of CO(2) (et-pCO(2)) in subjects with PD than in those with social phobia (SP) or generalized anxiety disorder (GAD), and (2) higher mean respiratory rate, lower venous et-pCO(2) and HCO(3)(-) concentration in subjects with PD than in those with SP. No publication bias was found.

CONCLUSIONS

Subjects with PD show a condition of baseline hyperventilation when compared to subjects with SP or GAD. Hematic variables suggest that the hyperventilation may be chronic. These results support the idea that baseline respiratory abnormalities are specific to PD pathophysiology. Further studies are needed to clarify whether these abnormalities are related to a malfunction of the respiratory system or to specific cognitive/emotional/behavioral factors in this population.

Collapsed Jugular Vein and abnormal cerebral blood flow changes in patients of Panic Disorder

OBJECTIVE

Panic disorder (PD) is characterized by panic attacks accompanied with respiratory symptoms. Internal jugular vein (IJV) alters its hemodynamics in response to respiration and which might cause cerebral blood flow (CBF) changes. In the present study, we compared (1) respiratory-related IJV hemodynamics and (2) CBF changes during Valsalva maneuver (VM) between PD and normal subjects.

METHODS

42 PD patients and age/gender-matched controls (14 men; 52.3 ± 11.4 years) were recruited. Duplex ultrasonography measured time-averaged mean velocity (TAMV) and lumen in IJV at baseline and deep inspiration. Lumen area <0.10 cm(2) at deep inspiration was defined as IJV collapse. CBF changes during VM were recorded by transcranial Doppler (TCD).

RESULTS

Compared with normal group, PD patients had significantly higher frequency of IJV collapse at deep inspiration (Left: 40.0% vs. 7.0%, p = 0.0003, Right: 17.0% vs. 0%, p = 0.0119). IJV collapse was associated with symptoms of respiratory subtype in our PD patients. PD group also had smaller lumen (Left: 0.53 ± 0.29 vs. 0.55 ± 0.26 cm(2), p = 0.8296, Right: 0.63 ± 0.36 vs. 0.93 ± 0.45 cm(2), p = 0.0014) and slower TAMV of IJV at baseline (Left: 11.8 ± 8.43 vs. 20.6 ± 16.5 cm/s, p = 0.0003, Right: 15.9 ± 9.19 vs. 24.1 ± 15.7 cm/s, p = 0.0062). PD patients with inspiration-induced IJV collapse had more decreased CBF during VM compared with the other PD patients and normal individuals respectively.

INTERPRETATION

We are the first to show that PD have less IJV flow at baseline and more frequent collapse at deep inspiration. Inspiration-induced IJV collapsed was associated with CBF decrement during VM in PD patients. These results suggest that venous drainage impairment might play a role in the pathophysiology of PD by influencing CBF.

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.

Panic disorder and the respiratory system: clinical subtype and challenge tests

INTRODUCTION

Respiratory changes are associated with anxiety disorders, particularly panic disorder (PD). The stimulation of respiration in PD patients during panic attacks is well documented in the literature, and a number of abnormalities in respiration, such as enhanced CO2 sensitivity, have been detected in PD patients. Investigators hypothesized that there is a fundamental abnormality in the physiological mechanisms that control breathing in PD.

METHODS

The authors searched for articles regarding the connection between the respiratory system and PD, more specifically papers on respiratory challenges, respiratory subtype, and current mechanistic concepts.

CONCLUSIONS

Recent evidences support the presence of subclinical changes in respiration and other functions related to body homeostasis in PD patients. The fear network, comprising the hippocampus, medial prefrontal cortex, amygdala and its brainstem projections, may be abnormally sensitive in PD patients, and respiratory stimulants like CO2 may trigger panic attacks. Studies indicate that PD patients with dominant respiratory symptoms are particularly sensitive to respiratory tests compared to those who do not manifest dominant respiratory symptoms, representing a distinct subtype. The evidence of changes in several neurochemical systems might be the expression of the complex interaction among brain circuits.

Hypersensitivity to hypercapnia: definition/(s)

Empirical evidence indicates that panic disorder (PD) patients experience hypersensitivity to hypercapnia, a condition in which the blood level of carbon dioxide exceeds the normal value. The importance of this research line is substantial and indeed, hypercapnic hypersensitivity has been advanced as a possible endophenotype of panic. Definitions of "hypersensitivity," however, have varied. The purpose of this brief review is to delineate and critique different definitions of hypercapnic hypersensitivity. Several definitions - panic attack rate, panic symptoms including dyspnea, subjective anxiety, and respiratory disturbance - are explored. The review concludes that although no ideal definition has emerged, marked anxiety post-hypercapnia has substantial support as a putative trait marker of PD. The term "subjective hypersensitivity" (Coryell et al., 2001) is re-introduced to denote pronounced anxiety post-hypercapnia and recommended for use along with its previous definition: increased self-reported anxiety measured on a continuous visual analog scale, already widely in use. Due to the well-established link between panic and respiration, definitional candidates focusing on aberrant respiratory response - less investigated as trait markers of PD in high risk studies - warrant scrutiny as well. Several reasons why definitional clarity might be beneficial are presented, along with ideas for future research.

Anxiogenic properties of a computer simulation for panic disorder with agoraphobia

BACKGROUND

There are several useful methods to induce anxiety in patients with panic disorder with agoraphobia (PDA). Our aim was to ascertain if a computer simulation (CS) could induce anxiety and physiologic alterations in PDA patients.

METHODS

10 healthy controls (HC) and 10 patients who fulfilled DSM-IV criteria for PDA were recruited for this study. The anxiety level was measured with the Subjective Units of Distress Scale (SUDS) and the Diagnostic Symptom Questionnaire (DSQ) was used to ascertain panic attack (PA) symptoms. The heart rate, skin conductance and respiration were monitored during exposure to the CS. The CS was a 3D computer animation of a short bus trip, from a first person perspective.

RESULTS

In PDA patients CS exposure increased anxiety levels, they also had higher scores in the DSQ and two of them had PA. Compared to the HC, the PDA patients had higher skin conductance level, electrodermal response magnitude, respiratory rate, tidal volume, and respiratory rate irregularities. The heart rate means were higher for PDA patients who had PA, followed by HC and PDA patients who did not have PA. There were no significant differences between the two groups regarding the sense of presence.

LIMITATIONS

The main limitations were the small sample size, and some PDA patients under medications.

CONCLUSIONS

This study indicated that CS exposure may induce anxiety, electrodermal and respiratory alterations in patients with PDA. CS exposure may be a useful tool in the research and treatment of PD patients.

Panic attacks and panic disorder in chronic obstructive pulmonary disease: a cognitive behavioral perspective

The prevalence of panic disorder in patients with chronic obstructive pulmonary disease (COPD) is up to 10 times greater than the overall population prevalence of 1.5-3.5%, and panic attacks are commonly experienced. When present, clinically significant anxiety decreases quality of life for COPD patients, and also increases health care costs. Therefore, understanding why COPD patients have such high rates of panic attacks and panic disorder is important for optimal management of COPD. The cognitive model of panic anxiety is the most widely accepted theory of panic attacks and panic disorder in physically healthy adults. According to this model, panic attacks occur when catastrophic misinterpretations of ambiguous physical sensations (such as shortness of breath or increased heart rate) increase arousal, creating a positive feedback loop that results in panic. As the major symptom of a terminal illness that threatens our most basic physical requirement, dyspnea in COPD is open to catastrophic misinterpretation. There is some experimental and clinical evidence for the applicability of the cognitive model of panic anxiety in COPD, and of the utility of cognitive behavior therapy (CBT), based on this model, for treating anxiety symptoms and panic attacks in COPD patients. However, there is much need for further studies. Evidence is increasing that mental health professionals, in collaboration with multi-disciplinary pulmonary teams, potentially have key roles to play in preventing and treating panic attacks and panic disorder in COPD patients. This review addresses diagnosis, epidemiology, theoretical conceptualizations, treatment, and recommendations for future research.

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.

Objective and subjective measures in recovery from a 35% carbon dioxide challenge

OBJECTIVES

Because hyperventilation, dyspnea, and a feeling of choking are often core features of a panic attack, respiration has been one of the most widely studied physiological parameters in panic disorder (PD) patients. A respiratory subgroup of PD, with distinct etiological pathways, has also been suggested. Investigation of the recovery phase following a respiratory challenge may be a reliable way to establish respiratory impairment in PD patients. The objective of the present study was to investigate the recovery phase from a 35% carbon dioxide challenge in PD patients and in healthy controls, and to test the hypothesis of a different respiratory pattern in patients, compared to control subjects.

METHODS

Eleven nonmedicated PD patients with or without agoraphobia, 11 medicated PD patients, and 11 control subjects took part in a 35% carbon dioxide and 65% oxygen inhalation challenge. Respiratory rate, partial pressure of carbon dioxide, heart rate, and blood pressure were recorded during the baseline phase (10 minutes) and the recovery phase (10 minutes). Visual Analogue Scale of Anxiety and Panic Symptom List scores were collected pre- and post-challenge.

RESULTS

Nonmedicated patients had increased variability in respiratory rate and partial pressure of carbon dioxide during recovery, compared with control subjects and medicated PD patients. Also, PD patients tended to have higher heart rates and to need more time to recover from the challenge than control subjects.

CONCLUSIONS

Results suggest that PD patients have less effective homeostatic control after their physiological equilibrium has been disrupted by a respiratory stressor.

Panic attacks and physical health problems in a representative sample: singular and interactive associations with psychological problems, and interpersonal and physical disability

BACKGROUND

Panic attacks may be a risk marker for a variety of psychological problems and are associated with increased impairment in a host of domains. However, previous studies have not investigated the role of physical illness in the panic attack-disability relations, which is striking due to findings that physical illness is linked to both panic attacks and disability. The present investigation examined the singular and interactive effects of panic attacks and physical illness in relation to psychological, interpersonal, and physical types of impairment.

METHOD

Adult participants (4,745) recruited from the statewide Colorado Social Health Survey were administered the diagnostic interview schedule.

RESULTS

As predicted, main effects of panic attacks and physical illness were significantly related to psychiatric comorbidity, depressive symptoms, interpersonal functioning, physical functioning, and perceived general health (p<.05 for all associations). Also as predicted, interaction of panic attacks and physical illness was significantly related to all of the outcome variables (p<.05 for all associations).

CONCLUSIONS

These findings suggest that individuals with both panic attacks and physical illness experience elevated disability across a variety of dimensions.

Comparing asthma and chronic obstructive pulmonary disease in terms of symptoms of anxiety and depression

OBJECTIVE

To evaluate the presence and severity of symptoms of anxiety and depression in individuals with asthma or chronic obstructive pulmonary disease.

METHODS

In order to evaluate symptoms of anxiety and depression, specific instruments of quantification (the State-Trait Anxiety Inventory and the Beck Depression Inventory, respectively) were administered to patients at an outpatient clinic for the treatment of asthma and chronic obstructive pulmonary disease. The population comprised 189 randomly and prospectively selected patients that were divided into three study groups (each with a different therapeutic objective): 40 patients with controlled asthma, 100 patients with uncontrolled asthma, and 49 patients with chronic obstructive pulmonary disease. Included among the variables studied, as part of the methodology, were symptoms of anxiety and depression. The data obtained were compared taking into consideration demographic and functional aspects, as well as the severity of the symptoms of anxiety and depression.

RESULTS

Among the asthma patients, the prevalence of moderate or severe anxiety was significantly higher than that observed among those with chronic obstructive pulmonary disease (p < 0.001). The uncontrolled asthma group presented significantly higher rates of depressive symptoms than did the controlled asthma group (p < 0.05).

CONCLUSION

The frequency of symptoms of anxiety and depression is greater among asthma patients than among patients with chronic obstructive pulmonary disease, which can make clinical control difficult.

Basilar artery blood flow velocity changes in patients with panic disorder following 35% carbon dioxide challenge

PURPOSE

We compared the mean basilar artery blood flow velocity (BABFV) between patients with panic disorder and healthy subjects both at rest and immediately following carbon dioxide (CO(2)) challenge, and examined the effects of treatment on BABFV.

METHODS

Twenty four patients with panic disorder with or without agoraphobia and 12 healthy comparison subjects were studied. Visual Analog Anxiety Scale was used to evaluate the anxiogenic effect of 35% CO(2) inhalation. Mean BABFV was monitored using transcranial Doppler ultrasonography at rest and 10, 20, 30, 60, 90, 120 s after 35% CO(2) challenge both before and after four weeks treatment with paroxetine.

RESULTS

The hemodynamic response pattern of basilar artery to CO(2) inhalation was significantly different between two groups. CO(2) rapidly triggered blood flow velocity in basilar artery amongst panic patients but not in healthy comparisons. The mean time to normalization of BABFV was significantly longer in panic patients. Four weeks of treatment with paroxetine led to a significantly reduced mean BABFV after 35% CO(2) inhalation in comparison with pretreatment.

CONCLUSIONS

Patients with panic disorder had impaired cerebral regulatory mechanisms observed as a change in response characteristics in BABFV in response to CO(2) inhalation. Treatment with paroxetine reduced the increase of BABFV seen in patients after the CO(2) challenge.

Fear induced complexity loss in the electrocardiogram of flight phobics: A multiscale entropy analysis

In this study we explored the changes in the variability and complexity of the electrocardiogram (ECG) of flight phobics (N=61) and a matched non-phobic control group (N=58) when they performed a paced breathing task and were exposed to flight related stimuli. Lower complexity/entropy values were expected in phobics as compared to controls. The phobic system complexity as well as the heart rate variability (HRV) were expected to be reduced by the exposure to fearful stimuli. The multiscale entropy (MSE) analysis revealed lower entropy values in phobics during paced breathing and exposure, and a complexity loss was observed in phobics during exposure to threatening situations. The expected HRV decreases were not found in this study. The discussion is focused on the distinction between variability and complexity measures of the cardiac output, and on the usefulness of the MSE analysis in the field of anxiety disorders.

Anxiety sensitivity-physical concerns as a moderator of the emotional consequences of emotion suppression during biological challenge: an experimental test using individual growth curve analysis

Anxiety-related responding to, and recovery from, a 5-min 10% carbon dioxide-enriched air presentation among 80 participants with no history of psychopathology was examined. Half of participants were instructed to suppress challenge-induced emotional responses, whereas their matched counterparts were instructed to observe such responses. Responding from immediately post-challenge through a 10-min recovery period was analyzed as a function of Anxiety Sensitivity-Physical Concerns and experimental condition using individual growth curve modeling. Anxiety Sensitivity-Physical Concerns moderated the effect of suppression only on emotion valence during recovery. In terms of main effects, suppression resulted in increased heart rate during recovery and Anxiety Sensitivity-Physical Concerns was positively associated with post-challenge self-reported anxiety. Results are discussed in terms of the potential role of inhibition-oriented affect regulation processes in the etiology of panic disorder.