Physiological markers for anxiety: Panic disorder and phobias

Puzzled by dysfunctional breathing disorder(s)? Consider the Bayesian brain hypothesis!

There is currently growing clinical concern regarding dysfunctional breathing disorder(s) (DBD), an umbrella term for a set of multidimensional clinical conditions that are characterized by altered breathing pattern associated with a variety of intermittent or chronic symptoms, notably dyspnea, in the absence or in excess of, organic disease. However, several aspects of DBD remain poorly understood and/or open to debate, especially the inconsistent relationship between the array of experienced symptoms and their supposedly underlying mechanisms. This may be partly due to a more general problem, i.e., the prevailing way we conceptualize symptoms. In the present article, after a brief review of the different aspects of DBD from the current perspective, I submit a call for considering DBD under the innovating perspective of the Bayesian brain hypothesis, i.e., a potent and novel model that fundamentally changes our views on symptom perception.

Higher polygenic risk scores for anxiety disorders are associated with reduced area in the anterior cingulate gyrus

Anxiety disorders are heterogeneous, show a moderate genetic contribution and are associated with inconsistent cortical structure alterations. Here, we investigated whether genetic factors for anxiety disorders contribute to cortical alterations by conducting polygenic risk score (PRS) analyses. We calculated PRSs for anxiety disorders at several P value thresholds (from P_T ≤ 5.0 × 10^-8 to P_T ≤ 1.0) based on the latest large-scale genome-wide association study of anxiety disorders from the UK biobank (25,453 cases; 58,113 controls) in an independent sample of psychiatrically and physically healthy subjects (n = 174). Using regression after adjusting for confounding factors, we tested whether these PRSs were associated with the surface area and cortical thickness in 34 bilateral brain regions extracted using FreeSurfer. A higher PRS for anxiety disorders at P_T ≤ 1.0 was significantly associated with a reduced right caudal anterior cingulate area (beta = -0.25, p_uncorrected = 9.51 × 10^-4, p_corrected = 0.032). PRSs based on more common SNPs, especially from P_T ≤ 0.01 to P_T ≤ 1.0, were associated with the right caudal anterior cingulate area (a maximum at P_T ≤ 0.5: R² = 0.066, beta = -0.27, p_uncorr = 3.81 × 10^-4, p_corr = 0.013). Furthermore, individuals in the highest quartile for anxiety disorder PRS had lower surface area and volume in the right anterior cingulate gyrus than those in the lowest quartile. We suggest a shared genetic etiology between anxiety disorders and structural features of the anterior cingulate gyrus, possibly contributing to the pathogenesis of anxiety disorders via emotional dysregulations. Our findings suggest the potential usefulness of PRS to reduce pathological heterogeneity among anxiety disorders.

Examining the effect of a wearable, anxiety detection technology on improving the awareness of anxiety signs in autism spectrum disorder: a pilot randomized controlled trial

BACKGROUND

Anxiety is prevalent in autism spectrum disorder (ASD) and can negatively impact physical and mental health. Self-awareness of anxiety signs is a key barrier to success of anxiety interventions for many children.

METHODS

To address this, we conducted a randomized controlled trial to assess whether the Anxiety Meter, a wearable, real-time anxiety detection technology, can improve awareness of anxiety symptoms and the initiation of relaxation techniques in children with ASD. Twenty-eight children with ASD were trained on the use of the Anxiety Meter and taught a diaphragmatic breathing relaxation technique over three visits. On the fourth visit, participants were randomized to either receive feedback of their anxiety level or no feedback from the Anxiety Meter while completing a stress-eliciting task (public speaking) and asked to engage in deep breathing if anxious.

RESULTS

Feedback from the Anxiety Meter was associated with increased likelihood of initiating deep breathing in response to anxiety.

LIMITATIONS

Limitations include the small sample size, imbalanced group matching for IQ and sex, and the controlled-laboratory settings which limit the statistical power and generalizability of the results to real-world settings.

CONCLUSIONS

Although these results are limited by the relatively small sample size, they support the feasibility of using a wearable device and real-time feedback to improve anxiety symptom awareness. Trial Registration ClinicalTrials.gov Identifier: NCT02160691, registration date: 06/05/2014.

Contributions of diagnostic, cognitive, and somatovisceral information to the prediction of fear ratings in spider phobic and non-spider-fearful individuals

BACKGROUND

Physiological responding is a key characteristic of fear responses. Yet, it is unknown whether the time-consuming measurement of somatovisceral responses ameliorates the prediction of individual fear responses beyond the accuracy reached by the consideration of diagnostic (e.g., phobic vs. non phobic) and cognitive (e.g., risk estimation) factors, which can be more easily assessed.

METHOD

We applied a machine learning approach to data of an experiment, in which spider phobic and non-spider fearful participants (diagnostic factor) faced pictures of spiders. For each experimental trial, participants specified their personal risk of encountering the spider (cognitive factor), as well as their subjective fear (outcome variable) on quasi-continuous scales, while diverse somatovisceral responses were registered (heart rate, electrodermal activity, respiration, facial muscle activity).

RESULTS

The machine-learning analyses revealed that fear ratings were predominantly predictable by the diagnostic factor. Yet, when allowing for learning of individual patterns in the data, somatovisceral responses contributed additional information on the fear ratings, yielding a prediction accuracy of 81% explained variance. Moreover, heart rate prior to picture onset, but not heart rate reactivity increased predictive power.

LIMITATIONS

Fear was solely assessed by verbal reports, only 27 females were considered, and no generalization to other anxiety disorders is possible.

CONCLUSIONS

After training the algorithm to learn about individual-specific responding, somatovisceral patterns can be successfully exploited. Our findings further point to the possibility that the expectancy-related autonomic state throughout the experiment predisposes an individual to experience specific levels of fear, with less influence of the actual visual stimulations.

Numbers (but not words) make math anxious individuals sweat: Physiological evidence

The study aimed to determine the specificity of math anxiety by measuring physiological arousal to the presentation of numerical and non-numerical stimuli. It also investigated whether math and trait anxieties share similar behavioral and physiological manifestations. Fifty-two female university students performed an experimental task including simple or complex arithmetical equations and math-related or neutral words. Participants' electrodermal activity (skin conductance response) was monitored during the task. Math and trait anxieties were measured using common explicit questionnaires. Results showed math anxiety levels were significantly related to physiological arousal during the performance of complex numerical tasks. Importantly, math anxiety significantly mediated the links between trait anxiety and physiological arousal in complex numerical tasks. The findings support previous work finding relations between math and trait anxieties, but also show math anxiety is a unique phenomenon with specific behavioral and physiological manifestations, especially during the processing of complex numerical information.

Investigation of a Capnometry Guided Respiratory Intervention in the Treatment of Posttraumatic Stress Disorder

Evidence‐based treatments for posttraumatic stress disorder (PTSD), including psychotherapies and medications, have high dropout and nonresponse rates, suggesting that more acceptable and effective treatments for PTSD are needed. Capnometry Guided Respiratory Intervention (CGRI) is a digital therapeutic effective in panic disorder that measures and displays end-tidal carbon dioxide (EtCO₂) and respiratory rate (RR) in real-time within a structured breathing protocol and may have benefit in PTSD by moderating breathing and EtCO₂ levels. We conducted a single-arm study of a CGRI system, Freespira®, to treat symptoms of PTSD. Participants with PTSD (n = 55) were treated for four weeks with twice-daily, 17-min at-home CGRI sessions using a sensor and tablet with pre-loaded software. PTSD and associated symptoms were assessed at baseline, end-of treatment, 2-months and 6-months post-treatment. Primary efficacy outcome was 50% of participants having ≥ 6-point decrease in Clinician Administered PTSD Scale (CAPS-5) score at 2-month follow up. Tolerability, usability, safety, adherence and patient satisfaction were assessed. CGRI was well tolerated, with 88% [95% CI 74–96%] having ≥ 6-point decrease in CAPS-5 scores at 2-months post-treatment follow up. Mean CAPS-5 scores decreased from 49.5 [s.d. = 9.2] at baseline to 27.1 [s.d. = 17.8] at 2-months post-treatment follow up. Respiratory rate decreased and EtCO₂ levels increased. Associated mental and physical health symptoms also improved. This CGRI intervention was safe, acceptable, and well-tolerated in improving symptoms in this study in PTSD. Further study against an appropriate comparator is warranted.

Trial registration Clinicaltrials.gov NCT#03039231.

Cardiorespiratory Functioning in Youth with Persistent Post-Concussion Symptoms: A Pilot Study

Dysregulation of the autonomic nervous system (ANS) may play an important role in the development and maintenance of persistent post-concussive symptoms (PPCS). Post-injury breathing dysfunction, which is influenced by the ANS, has not been well-studied in youth. This study evaluated cardiorespiratory functioning at baseline in youth patients with PPCS and examined the relationship of cardiorespiratory variables with neurobehavioral outcomes. Participants were between the ages of 13-25 in two groups: (1) Patients with PPCS (concussion within the past 2-16 months; n = 13) and (2) non-injured controls (n = 12). Capnometry was used to obtain end-tidal CO2 (EtCO2), oxygen saturation (SaO2), respiration rate (RR), and pulse rate (PR) at seated rest. PPCS participants exhibited a reduced mean value of EtCO2 in exhaled breath (M = 36.3 mmHg, SD = 2.86 mmHg) and an altered inter-correlation between EtCO2 and RR compared to controls. Neurobehavioral outcomes including depression, severity of self-reported concussion symptoms, cognitive catastrophizing, and psychomotor processing speed were correlated with cardiorespiratory variables when the groups were combined. Overall, results from this study suggest that breathing dynamics may be altered in youth with PPCS and that cardiorespiratory outcomes could be related to a dimension of neurobehavioral outcomes associated with poorer recovery from concussion.

Imagery-induced negative affect, social touch and frontal EEG power band activity

Social touch seems to modulate emotions, but its brain correlates are poorly understood. Here, we investigated if frontal power band activity in the electroencephalogram (EEG) during aversive mental imagery is modulated by social touch from one's romantic partner and a stranger. We observed the highest theta and beta power when imaging alone, next so when being touched by a stranger, with lowest theta and beta activity during holding hands with the loved one. Delta power was higher when being alone than with a stranger or a partner, with no difference between the two. Gamma power was highest during the stranger condition and lower both when being alone and with the partner, while alpha power did not change as a function of social touch. Theta power displayed a positive correlation with electrodermal activity supporting its relation to emotional arousal. Attachment style modulated the effect of touch on the EEG as only secure but not insecure partner bonding was associated with theta power reductions. Because theta power was sensitive to the experimental perturbations, mapped onto peripheral physiological arousal and reflected partner attachment style we suggest that frontal theta power might serve as an EEG derived bio-marker for social touch in emotionally significant dyads.

Efficacy of an internet-based exposure treatment for flying phobia (NO-FEAR Airlines) with and without therapist guidance: a randomized controlled trial

BACKGROUND

Internet-based treatments appear to be a promising way to enhance the in vivo exposure approach, specifically in terms of acceptability and access to treatment. However, the literature on specific phobias is scarce, and, as far as we know, there are no studies on Flying Phobia (FP). This study aims to investigate the effectiveness of an Internet-based exposure treatment for FP (NO-FEAR Airlines) that includes exposure scenarios composed of images and sounds, versus a waiting-list control group. A secondary aim is to explore two ways of delivering NO-FEAR Airlines, with and without therapist guidance.

METHODS

A randomized controlled trial (RCT) was conducted in which 69 participants were allocated to: 1) NO-FEAR Airlines totally self-applied, 2) NO-FEAR Airlines with therapist guidance, 3) a waiting-list control group. Primary outcome measures were the Fear of Flying Questionnaire-II and the Fear of Flying Scale. Secondary outcomes included the Fear and Avoidance Scales, Clinician Severity Scale, and Patient's Improvement scale. Behavioral outcomes (post-treatment flights and safety behaviors) were also included. Mixed-model analyses with no ad hoc imputations were conducted for primary and secondary outcome measures.

RESULTS

NO-FEAR Airlines (with and without therapist guidance) was significantly effective, compared to the waiting list control group, on all primary and secondary outcomes (all ps < .05), and no significant differences were found between the two ways of delivering the intervention. Significant improvements on diagnostic status and reliable change indexes were also found in both treatment groups at post-treatment. Regarding behavioral outcomes, significant differences in safety behaviors were found at post-treatment, compared to the waiting list. Treatment gains were maintained at 3- and 12-month follow-ups.

CONCLUSION

FP can be treated effectively via the Internet. NO-FEAR Airlines helps to enhance the exposure technique and provide access to evidence-based psychological treatment to more people in need. These data are congruent with previous studies highlighting the usefulness of computer-assisted exposure programs for FP, and they contribute to the literature on Internet-based interventions. To the best of our knowledge, this is the first RCT to investigate the effectiveness of an Internet-based treatment for FP and explore two ways of delivering the intervention (with and without therapist guidance).

TRIAL REGISTRATION

Clinicaltrials.gov: NCT02298478 ( https://clinicaltrials.gov/ct2/show/NCT02298478 ). Trial registration date 3 November 2014.

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.

Associations between psychometrically assessed life history strategy and daily behavior: data from the Electronically Activated Recorder (EAR)

Life history theory has generated cogent, well-supported hypotheses about individual differences in human biodemographic traits (e.g., age at sexual maturity) and psychometric traits (e.g., conscientiousness), but little is known about how variation in life history strategy (LHS) is manifest in quotidian human behavior. Here I test predicted associations between the self-report Arizona Life History Battery and frequencies of 12 behaviors observed over 72 h in 91 US college students using the Electronically Activated Recorder (EAR), a method of gathering periodic brief audio recordings as participants go about their daily lives. Bayesian multi-level aggregated binomial regression analysis found no strong associations between ALHB scores and behavior frequencies. One behavior, presence at amusement venues (bars, concerts, sports events) was weakly positively associated with ALHB-assessed slow LHS, contrary to prediction. These results may represent a challenge to the ALHB's validity. However, it remains possible that situational influences on behavior, which were not measured in the present study, moderate the relationships between psychometrically-assessed LHS and quotidian behavior.

Lifespan anxiety is reflected in human amygdala cortical connectivity

The amygdala plays a pivotal role in processing anxiety and connects to large‐scale brain networks. However, intrinsic functional connectivity (iFC) between amygdala and these networks has rarely been examined in relation to anxiety, especially across the lifespan. We employed resting‐state functional MRI data from 280 healthy adults (18–83.5 yrs) to elucidate the relationship between anxiety and amygdala iFC with common cortical networks including the visual network, somatomotor network, dorsal attention network, ventral attention network, limbic network, frontoparietal network, and default network. Global and network‐specific iFC were separately computed as mean iFC of amygdala with the entire cerebral cortex and each cortical network. We detected negative correlation between global positive amygdala iFC and trait anxiety. Network‐specific associations between amygdala iFC and anxiety were also detectable. Specifically, the higher iFC strength between the left amygdala and the limbic network predicted lower state anxiety. For the trait anxiety, left amygdala anxiety–connectivity correlation was observed in both somatomotor and dorsal attention networks, whereas the right amygdala anxiety–connectivity correlation was primarily distributed in the frontoparietal and ventral attention networks. Ventral attention network exhibited significant anxiety–gender interactions on its iFC with amygdala. Together with findings from additional vertex‐wise analysis, these data clearly indicated that both low‐level sensory networks and high‐level associative networks could contribute to detectable predictions of anxiety behaviors by their iFC profiles with the amygdala. This set of systems neuroscience findings could lead to novel functional network models on neural correlates of human anxiety and provide targets for novel treatment strategies on anxiety disorders. Hum Brain Mapp 37:1178–1193, 2016. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Hyperventilation in asthma: a validation study of the Nijmegen Questionnaire--NQ

INTRODUCTION

The Nijmegen questionnaire (NQ) has previously been used for screening the hyperventilation syndrome (HVS) in asthmatics. However, no validity study has been reported so far.

OBJECTIVE

To examine the validity and reliability of the NQ in asthma patients and identify the prevalence of HVS.

METHODS

The NQ (n = 162) was examined for translation, construct, cross-sectional and discriminant validity as well as for internal consistency and test-retest reliability.

RESULTS

Principal component analysis and exploratory factor analysis revealed a single factor solution with 11 items and 58.6% of explained variability. These 11 NQ items showed high internal consistency (Cronbach's alpha = 0.92) and test-retest reliability (IR = 0.98). Higher NQ scores were found in the following subgroups: women versus men (p < 0.01); participants with moderate versus mild asthma (p < 0.001) or uncontrolled versus controlled asthma (p < 0.001), and participants with breath-hold time (BHT) < 30 versus ≥ 30 s (p < 0.01) or end-tidal CO2 (ETCO2) ≤ 35 versus >35 mmHg (p < 0.001). A cut-off score of >17 discriminated the participants with regard to the presence of HVS. The NQ showed 92.73% sensitivity and 91.59% specificity. The total NQ score was found significantly correlated with ETCO2 (r = -0.68), RR (r = 0.66) and BHT (r = -0.65). The prevalence of HVS was found 34%.

CONCLUSION

The NQ is a valid and reliable questionnaire for screening HVS in patients with stable mild-to-moderate asthma.

Coordination of breathing with nonrespiratory activities

Many articles in this section of Comprehensive Physiology are concerned with the development and function of a central pattern generator (CPG) for the control of breathing in vertebrate animals. The action of the respiratory CPG is extensively modified by cortical and other descending influences as well as by feedback from peripheral sensory systems. The central nervous system also incorporates other CPGs, which orchestrate a wide variety of discrete and repetitive, voluntary and involuntary movements. The coordination of breathing with these other activities requires interaction and coordination between the respiratory CPG and those governing the nonrespiratory activities. Most of these interactions are complex and poorly understood. They seem to involve both conventional synaptic crosstalk between groups of neurons and fluid identity of neurons as belonging to one CPG or another: neurons that normally participate in breathing may be temporarily borrowed or hijacked by a competing or interrupting activity. This review explores the control of breathing as it is influenced by many activities that are generally considered to be nonrespiratory. The mechanistic detail varies greatly among topics, reflecting the wide variety of pertinent experiments.

Responses to voluntary hyperventilation in children with separation anxiety disorder: implications for the link to panic disorder

BACKGROUND

Biological theories on respiratory regulation have linked separation anxiety disorder (SAD) to panic disorder (PD). We tested if SAD children show similarly increased anxious and psychophysiological responding to voluntary hyperventilation and compromised recovery thereafter as has been observed in PD patients.

METHODS

Participants were 49 children (5-14 years old) with SAD, 21 clinical controls with other anxiety disorders, and 39 healthy controls. We assessed cardiac sympathetic and parasympathetic, respiratory (including pCO2), electrodermal, electromyographic, and self-report variables during baseline, paced hyperventilation, and recovery.

RESULTS

SAD children did not react with increased anxiety or panic symptoms and did not show signs of slowed recovery. However, during hyperventilation they exhibited elevated reactivity in respiratory variability, heart rate, and musculus corrugator supercilii activity indicating difficulty with respiratory regulation.

CONCLUSIONS

Reactions to hyperventilation are much less pronounced in children with SAD than in PD patients. SAD children showed voluntary breathing regulation deficits.

Anxiety sensitivity moderates the relationship of changes in physiological arousal with flight anxiety during in vivo exposure therapy

Physiological sensations and discomfort constitute the major symptoms reported by aviophobics. Anxiety sensitivity (AS) seems to moderate the relationship between self-reported somatic sensations and flight anxiety, and AS has been identified as a vulnerability factor for flight phobia. In this study we examined whether AS moderates the effects of somatic sensations and autonomic nervous system reactivity on flight anxiety induced by real flight. In fifty aviophobics participating in Cognitive Behaviour Group Therapy (CBGT), flight anxiety, somatic sensations and autonomic nervous system reactivity were assessed during a guided return flight. Results indicate that physiological reactivity interacted with AS. Changes in heart rate and parasympathetic activity were more strongly associated with changes in reported flight anxiety for high AS participants, and less for participants low on AS. Results did not indicate a moderating effect of AS on the relationship between self-reported somatic sensations and flight anxiety. Our results suggest that therapy for flight phobia might benefit from addressing the physical effect of anxiety, by means of cognitive restructuring and exposure to interoceptive stimuli, particularly in aviophobics high in AS.

The Sensitivity of Physiological Measures to Phobic and Nonphobic Fear Intensity

We investigated whether amygdala activation, autonomic responses, respiratory responses, and facial muscle activity (measured over the brow and cheek [fear grin] regions) are all sensitive to phobic versus nonphobic fear and, more importantly, whether effects in these variables vary as a function of both phobic and nonphobic fear intensity. Spider-phobic and comparably low spider-fearful control participants imagined encountering different animals and rated their subjective fear while their central and peripheral nervous system activity was measured. All measures included in our study were sensitive to variations in subjective fear, but were related to different ranges and positions on the subjective fear level continuum. Left amygdala activation, heart rate, and facial muscle activity over the cheek region captured fear intensity variations even within narrowly described regions on the fear level continuum (here within extremely low levels of fear and within considerable phobic fear). Skin conductance and facial muscle activity over the brow region did not capture fear intensity variations within low levels of fear: skin conductance mirrored only extreme levels of fear, and activity over the brow region distinguished phobic from nonphobic fear but also low-to-moderate and high phobic fear. Finally, respiratory measures distinguished phobic from nonphobic fear with no further differentiation within phobic and nonphobic fear. We conclude that a careful consideration of the measures to be used in an investigation and the population to be examined can be critical in order to obtain significant results.

Damage to the right dorsal anterior cingulate cortex induces panic disorder

Brain imaging studies suggest that panic disorder (PD) is mediated by several brain regions, including the anterior cingulate cortex (ACC). In the present report we describe a patient who experienced a panic attack during awake surgery (case 1) and another patient who developed PD after surgery and radiotherapy (case 2). In case 1, the patient experienced repeated panic attacks when the tumor at the upper border of right dorsal ACC was removed during awake surgery. In case 2, the patient developed PD at six months after surgery and Cyberknife radiotherapy. MRI examination revealed that the dorsal ACC size was reduced at six months after surgery and that the dorsal ACC was absent at two years after surgery, possibly due to radiotherapy-induced damage by radiotherapy. Profile of mood states (POMS) testing characterized the presence of tension-anxiety as the common abnormal symptom in cases 1 and 2. In conclusion, these results suggest that damage to the right dorsal ACC can induce PD and that this structure likely plays a pathophysiologic role in PD.

Naturalistically observed sighing and depression in rheumatoid arthritis patients: a preliminary study

OBJECTIVE

This study tested the degree to which naturalistically observed sighing in daily life is a behavioral indicator of depression and reported physical symptoms (i.e., experienced pain and flare days) in rheumatoid arthritis (RA) patients.

DESIGN

Thirteen RA patients wore the Electronically Activated Recorder (EAR), an observational ambulatory assessment tool, for two weekends (Friday through Sunday) approximately one month apart. The EAR periodically recorded snippets of ambient sounds from participants' momentary environments (50 s every 18 min). Sighs were coded from the sampled ambient sounds.

MAIN OUTCOME MEASURES

Depression was assessed with the Center for Epidemiological Studies Depression Scale and the Beck Depression Inventory. Pain during the past month was assessed with a 10-cm visual-analog scale, and number of flare days during the prior 6 months was reported.

RESULTS

Sighing was significantly and strongly related to patients' levels of depression and nonsignificantly and less strongly related to their reported pain and number of flare days.

CONCLUSION

The findings suggest that sighing can serve as an observable marker of depression in RA patients. Because the sample size was small, the findings should be considered preliminary.

Threat of suffocation and defensive reflex activation

The current study examined emotional reflex reactions of participants threatened with respiratory distress caused by imposing a resistive load at inspiration. Cues signaling threat (breathing MAY be difficult) and safe periods were intermixed while startle reflexes, heart rate, skin conductance, and facial EMG activity were measured. Compared to safe cues, threat cues elicited significant startle potentiation, enhanced skin conductance, heightened corrugator EMG changes, and pronounced "fear bradycardia" consistent with defensive activation in the context of threatened respiratory dysfunction. These data indicate that anticipating respiratory resistance activates defensive responding, which may mediate symptomatology in patients with panic and other anxiety disorders.

Physiological reactivity to phobic stimuli in people with fear of flying

OBJECTIVE

The nature of the relationship between physiological and subjective responses in phobic subjects remains unclear. Phobics have been thought to be characterized by a heightened physiological response (physiological perspective) or by a heightened perception of a normal physiological response (psychological perspective).

METHOD

In this study, we examined subjective measures of anxiety, heart rate (HR), and cardiac autonomic responses to flight-related stimuli in 127 people who applied for fear-of-flying therapy at a specialized treatment center and in 36 controls without aviophobia.

RESULTS

In keeping with the psychological perspective, we found a large increase in subjective distress (eta(2)=.43) during exposure to flight-related stimuli in the phobics and no change in subjective distress in the controls, whereas the physiological responses of both groups were indiscriminate. However, in keeping with the physiological perspective, we found that, within the group of phobics, increases in subjective fear during exposure were moderately strong coupled to HR (r =.208, P=.022) and cardiac vagal (r =.199, P=.028) reactivity. In contrast to predictions by the psychological perspective, anxiety sensitivity did not modulate this coupling.

CONCLUSION

We conclude that subjective fear responses and autonomic responses are only loosely coupled during mildly threatening exposure to flight-related stimuli. More ecologically valid exposure to phobic stimuli may be needed to test the predictions from the physiological and psychological perspectives.

The association between irritable bowel syndrome and the anxiety vulnerability factors: body vigilance and discomfort intolerance

Individuals with Irritable Bowel Syndrome (IBS) endorse greater negative affect, including anxiety psychopathology. To examine the role anxiety plays in the maintenance and exacerbation of IBS the links between IBS and two anxiety related constructs, body vigilance and discomfort intolerance, were examined. A non-treatment seeking college sample (N = 476) completed measures that assessed IBS symptomatology, vigilance to bodily sensations and ability to tolerate physical discomfort. A total of 4.2 percent of the sample met Rome II criteria for IBS. Consistent with the hypotheses, IBS symptoms were associated with increased vigilance to bodily sensations and increased desire to avoid these sensations.

Temporal stability and coherence of anxiety, dyspnea, and physiological variables in panic disorder

Twenty-five panic disorder (PD) patients, 19 social phobics (SP), and 20 healthy controls (HC) sat quietly for 15 min, rating their anxiety and dyspnea every 30s while respiratory, cardiovascular, and electrodermal responses were recorded. No panic attacks were reported. For self-reported anxiety and dyspnea, within-subject variability over time was higher in PD than in SP or HC. In PD within-subject correlations across 30-s epochs were significant for (a) self-reported anxiety versus dyspnea, end-tidal pCO2, minute volume, duty cycle, skin conductance level, and interbeat interval, and for (b) dyspnea versus end-tidal pCO2, minute volume, tidal volume, and inspiratory flow rate. Several positive or negative correlations were greater in PD than in other groups. Thus in PD, experienced anxiety and dyspnea are temporally unstable but are correlated with each other and with fluctuations in respiratory and autonomic variables, even in the absence of panic attacks.

An exploration of secondary sex ratios among women diagnosed with anxiety disorders

BACKGROUND

Theory suggests that natural selection conserved reactivity in part because highly reactive women spontaneously abort less fit conceptuses, particularly small males. Other literature argues that high reactivity manifests clinically as anxiety disorders. If true, births to women diagnosed with anxiety disorders should exhibit a low secondary sex ratio (i.e. ratio of male to female births). We explored whether births to women diagnosed with anxiety disorders exhibit a lower sex ratio than births to women diagnosed with other psychiatric disorders, or to women without mental health diagnoses.

METHODS

We performed a case-control comparison of the secondary sex ratios among groups of women categorized by mental health diagnosis using birth records linked to data from California County Mental Health system records. We compared sex ratios among 5994 deliveries to mothers diagnosed with anxiety disorders, 23 443 deliveries to mothers diagnosed with other psychiatric disorders and 1 099 198 'comparison' births.

RESULTS

Although comparison births exhibited a higher sex ratio than births to women diagnosed with anxiety disorders or with other diagnoses, differences were not statistically significant. Births to African American women diagnosed with anxiety disorders, however, exhibited sex ratios significantly lower than comparison births among African Americans (OR = 0.89, P = 0.038) or births to African American women with other mental health diagnoses (OR = 0.88, P = 0.042).

CONCLUSIONS

We found that infants born to African American women diagnosed with anxiety disorders exhibited a significantly lower secondary sex ratio than reference groups. We urge confirmatory tests of our findings and discuss implications of the reactivity/anxiety hypothesis for psychiatry, obstetrics and public health.

The psychophysiology of blood-injection-injury phobia: looking beyond the diphasic response paradigm

Blood-injection-injury (BII) phobia is an anxiety disorder that may be accompanied by vasovagal fainting during confrontation with the feared stimuli. The underlying pattern of autonomic regulation has been characterized as a diphasic response, with initial increases in heart rate and blood pressure that are typical of a fight-flight response, and subsequent drops in blood pressure and/or heart rate that may precipitate vasovagal fainting. Tensing skeletal muscles of the arms, legs, and trunk (applied tension) has been proposed as a technique to cope with this dysregulation. This review critically examines the empirical basis for the diphasic response and its treatment by applied tension in BII phobia. An alternative perspective on the psychophysiology of BII phobia and vasovagal fainting is offered by focusing on hypocapnia that leads to cerebral blood flow reductions, a perspective supported by research on neurocardiogenic and orthostatically-induced syncope. The evidence may indicate a role for respiration-focused coping techniques in BII phobia.

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

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

Virtual reality exposure therapy in the treatment of driving phobia

A growing number of researches has appeared on virtual reality exposure therapy (VRET) to treat anxiety disorders. The purpose of this article was to review some evidences that support the VRET efficacy to treat driving phobia. The studies were identified through computerized search (PubMed/Medline, Web of Science, and Scielo databases) from 1984 to 2007. Some findings are promising. Anxiety/avoidance ratings declined from pre to post-treatment. VRET may be used as a first step in the treatment of driving phobia, as long as it may facilitate the in vivo exposure, thus reducing risks and high costs of such exposure. Notwithstanding, more randomized/controlled clinical trials are required to prove its efficacy.

Caffeine challenge in patients with panic disorder: baseline differences between those who panic and those who do not

A proportion of patients with panic disorder (PD) display an increased sensitivity to the anxiogenic/panicogenic properties of caffeine. The aim of this study is to identify probable baseline differences between PD patients who panic and those who do not, after caffeine administration. In a randomized, double-blind, cross-over experiment performed in two occasions 3-7 days apart, 200 and 400 mg of caffeine, respectively, were administered in a coffee form to 23 patients with PD with or without Agoraphobia. Evaluations included the State-Trait Anxiety Inventory, the DSM-IV 'panic attack' symptoms (visual analogue scale form), the Symptom Checklist-90-Revised (SCL-90-R), as well as breath-holding (BH) duration, heartbeat perception accuracy and heart rate. Only those patients who did not present a panic attack after both challenges ('no panic group', N=14, 66.7%), and those who presented a panic attack after at least one challenge ('panic group', n=7, 33.3%) were included in the analysis. The panickers, compared to the non-panickers, presented at baseline: significantly higher total score of the SCL-90-R; significantly higher scores on all the SCL-90-R clusters of symptoms, except that of 'paranoid ideation'; significantly lower BH duration. The present preliminary findings indicate that PD patients who panic after a 200 mg or a 400 mg caffeine challenge, compared to the PD patients who do not panic after both of these challenges, may present at baseline significantly higher non-specific general psychopathology--as reflected in the SCL-90-R--and significantly shorter BH duration.

The role of fear and anxiety in the familial risk for major depression: a three-generation study

BACKGROUND

The overlap between anxiety and major depressive disorder (MDD), the increased risk for depression and anxiety in offspring of depressed parents, the sequence of onset with anxiety preceding MDD, and anxiety as a predictor of depression are well established. The specificity of anxiety disorders in these relationships is unclear. This study, using a longitudinal high-risk design, examined whether anxiety disorders associated with the emotions fear and anxiety mediate the association between parental and offspring depression.

METHOD

Two hundred and twenty-four second-generation and 155 third-generation descendants at high and low risk for depression because of MDD in the first generation were interviewed over 20 years. Probit and Cox proportional hazard models were fitted with generation 2 (G2) or G3 depression as the outcome and parental MDD as the predictor. In G2 and G3, fear- (phobia or panic) and anxiety-related [overanxious or generalized anxiety disorder (GAD)] disorders were examined as potential mediators of increased risk for offspring depression, due to parental MDD.

RESULTS

In G2, fear-related disorders met criteria for mediating the association between parental MDD and offspring MDD whereas anxiety-related disorders did not. These results were consistent, regardless of the analytic methods used. Further investigation of the mediating effect of fear-related disorders by age of onset of offspring MDD suggests that the mediating effect occurs primarily in adolescent onset MDD. The results for G3 appear to follow similar patterns.

CONCLUSIONS

These findings support the separation of anxiety disorders into at least two distinct forms, particularly when examining their role in the etiology of depression.

Social anxiety symptoms uniquely predict fear responding to 35% CO(2) challenge

The vast majority of biological challenge studies have focused on panic disorder though there is a small literature suggesting that patients with social anxiety disorder (SAD) show comparable responding. The SAD literature is potentially confounded, however, by the fact that many patients with SAD experience panic attacks. These patients also show elevated negative affect and anxiety sensitivity, factors that are also associated with increased fear responding to challenge. By controlling for these factors, the present report was able to evaluate whether social anxiety symptoms were uniquely associated with fearful responding to a 35% CO(2) challenge. A large nonclinical sample of young adults (N=120) screened for a history of panic attacks completed a 35% CO(2) challenge. Those high (versus low) in social anxiety showed approximately 2.5 times greater risk for experiencing substantial increases in anxiety in response to the challenge. This significant association was maintained after controlling for anxiety sensitivity and general negative affect. These data provide novel evidence suggesting that social anxiety symptoms are uniquely associated with anxious responding to 35% CO(2) challenge and this sensitivity appears to precede the development of panic attacks.

Fear responding to 35% CO(2) challenge as a vulnerability marker for later social anxiety symptoms

The majority of biological challenge studies have focused on panic disorder though there is a small literature suggesting that patients with social anxiety disorder (SAD) show comparable responding. These cross-sectional studies suggest that CO(2) reactivity may be a marker of vulnerability to social anxiety. However, the nature of this association is unclear due to design limitations in this literature. The present report prospectively evaluated whether response to a 20% CO(2) challenge was predictive of later changes in social anxiety symptoms. A large non-clinical sample of young adults (N=404) screened for axis I disorders completed a 20% CO(2) challenge and were followed for approximately 18 months. Consistent with the vulnerability hypothesis, those showing greater reactivity to the CO(2) challenge showed increased social anxiety symptoms over time. This significant association was maintained after controlling for gender and trait anxiety. These data provide novel evidence suggesting that CO(2) sensitivity is predictive of the development of social anxiety symptoms.

Altered cingulate white matter connectivity in panic disorder patients

OBJECTIVE

Functional imaging studies of panic disorder subjects suggest an increased activation of the cingulate regions of the brain. Aim of the current study was to explore the white matter connectivity differences between subjects with panic disorder and healthy comparison subjects.

METHOD

Structural white matter connectivity, as determined from fractional anisotropy (FA) values obtained by diffusion tensor imaging, was assessed for anterior and posterior cingulate regions in 24 panic disorder patients and 24 age and sex-matched healthy comparison subjects.

RESULTS

Subjects with panic disorder exhibited significantly greater FA values in left anterior and right posterior cingulate regions (by 13.3% and 19.6%, respectively) relative to comparison subjects. White matter connectivity for these two cingulate regions was also positively correlated with clinical severity, as determined by Panic Disorder Severity Scale. FA values in left anterior cingulate region negatively correlated with the time of Trail Making Tests and positively with Digit Symbol Substitution Test.

CONCLUSIONS

Findings suggest a potential 'enhancement' in white matter connectivity in left anterior and right posterior cingulate regions in panic disorder, and that these changes may play an important role in mediating clinical symptoms of panic disorder.

Organization of brain somatomotor-sympathetic circuits

Numerous physiological and emotionally motivated behaviors require concomitant activation of somatomotor and sympathetic efferents. Likewise, adaptive and maladaptive responses to stress are often characterized by simultaneous recruitment of these efferent systems. This review describes recent literature that outlines the organization of somatomotor-sympathetic circuitry in the rat. These circuits were delineated by employing recombinant pseudorabies (PRV) viral vectors as retrograde trans-synaptic tract tracers. In these studies PRV-152, a strain that expresses enhanced green fluorescent protein, was injected into sympathectomized hindlimb muscle, while PRV-BaBlu, which expresses beta-galactosidase, was injected into the adrenal gland in the same animals. Immunofluorescent methods were then used to determine the presence of putative dual-function neurons that were infected with both viral strains. These somatomotor-sympathetic neurons (SMSNs) were detected in a number of brain regions. However, the most prominent nodes in this circuitry included the paraventricular, dorsomedial, and lateral nuclei of the hypothalamus, ventrolateral periaqueductal grey and ventromedial medulla. Phenotypic studies revealed subsets of SMSNs to be capable of synthesizing serotonin, or to contain neuroactive peptides vasopressin, oxytocin, orexins, or melanin-concentrating hormone. Based on these data and the results of studies employing monosynaptic tracers a central somatomotor-sympathetic circuit is proposed. This circuitry is likely recruited in diverse situations, including stress responses, cold defense, exercise and sleep. Furthermore, activation of specific classes of SMSNs likely shapes distinct stress-coping strategies. Dysregulation in the organization and function of this circuit may also contribute to the expression of physical symptoms of affective disorders, such as major depression, anxiety and panic.

Ultrasound imaging of the lateral abdominal wall muscles in individuals with lumbopelvic pain and signs of concurrent hypocapnia

The purpose of this study was to compare the change in thickness of transversus abdominis (TrA) and internal oblique (IO) muscles, during resting supine respiration, in individuals with lumbopelvic pain (LP) to those who in addition to LP, demonstrate signs of concurrent hypocapnia (LP&HYPO). B-mode ultrasound images were obtained at the height of inspiration, and at the end of expiration, over three subsequent breaths during a single session. The average percent change in thickness of TrA during resting respiration in the LP&HYPO group (20.8+/-7.6%) was found to be statistically greater (P<0.001) than that of the LP only group (1.3+/-5.8%), while the difference between the groups for the percent change in thickness of IO (LP&HYPO 9.2+/-8.1%, LP 2.0+/-7.2%) did not differ (P=0.073). These findings suggest that respiratory modulation of TrA thickness, as measured by ultrasound imaging, greater than 20%, detected in a resting supine position, may be associated with an episode of hypocapnia, and if present warrants further investigation.

Panic symptoms at the interface of body and mind

Panic disorder is a common illness with significant impact on function and, at times, disabling consequences. Advances over recent years have yielded potential pathophysiologic mechanisms, including neurotransmitter systems and neural substrates. This article provides an overview of various models and hypotheses regarding the etiology of panic disorder. Because its symptoms overlap with the symptoms of various medical disorders, this discussion reviews the comorbidity of panic disorder with medical conditions, especially cardiac and respiratory disorders.

Neuroscientific Psychophysiology: The International Organization of Psychophysiology (I.O.P.) associated with the United Nations (New York) in the 21st Century

This Presidential Address 2004 emphasizes the pivotal role of Psychophysiology as an integrated neuroscience with a panoply of electrophysiological and neuroimaging technologies for the establishment of methodologically crucial conceptual links for the understanding and mapping of brain functions pertaining to cognitive, emotional and motivational processes. Moreover, Psychophysiology's unique neuroscientific perspective by integrating functions of central and autonomic nervous systems with behavior in health and disease is underlined. Based on these developments, the progress of rigorous neuroscientific Clinical Psychophysiology offers possibilities for diagnosis, treatment and objective evaluation of therapeutic outcome in various pathological conditions.