A threat from within: Learning to fear by observing aversive bodily symptoms in others.

Although observational fear learning has been implicated in the development of phobic-related fears, studies investigating observational learning of fear of bodily symptoms remain scarce. Therefore, the aim of the present study was to investigate whether fear in response to bodily symptoms can be acquired simply by observing a fearful reaction to provocation of aversive bodily symptoms in others. Forty healthy participants underwent an observational fear conditioning paradigm consisting of two phases. In the first phase, participants observed a demonstrator reacting to an aversive bodily symptom provocation (unconditioned stimulus or US, i.e., labored breathing) paired with one conditioned stimulus (CS+) but not with the other one (CS-, both CSs were geometric symbols presented on a screen the demonstrator was watching). In the second phase, participants were directly presented with the same conditioned stimuli, but in the absence of the US. Our results revealed enhanced conditioned fear responses in the beginning of the second phase to the CS + as compared to CS-, as indexed by greater skin conductance and subjective fear responses, as well as greater potentiation of startle eyeblink responses to the CS + as compared to the ITI. Taken together, these findings implicate that fear of bodily symptoms can be learned through observation of others, that is, without first-hand experience of bodily threat.

Role of interoceptive fear and maladaptive attention and behaviors in the escalation of psychopathology-a network analysis.

The complex interplay of fear, attention, and behavior toward bodily sensations with psychopathological symptoms and how they mutually influence and potentially reinforce one another remains to be fully elucidated. In this study, we used a network analytical approach to unravel these complex interactions. Specifically, we aimed to identify central symptoms and etiologically relevant factors that might be associated with anxiety and depressive core symptoms. To this end, the following clusters were assessed in 791 adults: interoceptive fear, interoceptive attention, maladaptive behaviors related to bodily sensations, and core symptoms of anxiety and depression. This network was modeled using a Gaussian Graphical Model. Central variables (nodes) were identified using centrality indices and bridge analysis. Self-examination and attention to bodily sensations emerged as central nodes. Moreover, time spent paying attention to bodily sensations, fear of anxiety-related sensations, and self-examination were identified as central bridge nodes, that is, central nodes connecting psychopathologically relevant symptom clusters. The present study indicates that fear of bodily sensations, the amount of attention and time spent focusing on somatic sensations, and self-examination are central factors. The findings suggest potential targets for future longitudinal studies on the impact of these factors for the escalation of anxiety and depressive symptoms.

Central variables were identified through centrality indices and bridge analysisAttention to bodily sensations and self-examination were identified as central nodesFear of bodily sensations and self-examination emerged as central bridge nodesTime spent paying attention to body sensations also emerged as central bridge nodeResults suggest possible targets for future experimental and longitudinal research.

Health anxiety amplifies fearful responses to illness-related imagery.

Severe health anxiety (HA) is characterized by excessive worry and anxiety about one's health, often accompanied by distressing intrusive imagery of signs of a serious illness or potentially receiving bad news about having a life-threatening disease. However, the emotional responses to these illness-related mental images in relation to HA have not been fully elucidated. Emotional responses to mental imagery of 142 participants were assessed in a well-controlled script-driven imagery task, systematically comparing emotional responses to illness-related imagery with neutral and standard fear imagery. The results revealed that participants reported higher anxiety, aversion, emotional arousal, and a stronger avoidance tendency during imagery of fear and illness-related scenes compared to neutral scenes. Importantly, the emotional modulation varied by the level of HA, indicating that individuals with higher HA experienced stronger emotional responses to illness-related imagery. This association between HA and fearful imagery could not be better accounted for by other psychological factors such as trait anxiety, anxiety sensitivity, somatic symptom severity, or symptoms of depression and anxiety. Fearful responding to standard threat material was not associated with HA. The present findings highlight the importance of considering fear responding to mental imagery in understanding and addressing HA.

"The mere imagination scares me"-evidence for fear responses during mental imagery of pain-associated interoceptive sensations in adolescents with chronic pain.

ABSTRACT: According to the bio-informational theory of emotion by Lang, mental imagery of fearful stimuli activates physiological and behavioural response systems, even in the absence of sensory input. We investigated whether instructed mental imagery of pain-associated (not painful) interoceptive sensations entails a threat value and elicits increased startle response, skin conductance level (SCL), and heart rate (HR) indicative of defensive mobilization in adolescents with chronic pain. Additionally, self-reported measures (fear, fear of pain, desire to avoid) were assessed. Adolescents (11-18 years) with chronic headache (CH, n = 46) or chronic abdominal pain (CAP, n = 29) and a control group (n = 28) were asked to imagine individualized pain-associated, neutral and standardized fear scripts. During pain-associated compared with neutral imagery, both pain groups showed higher mean HR, with CH also showing higher HR reactivity, while HR acceleration was not observed within control group. In contrast, during pain-associated compared with neutral imagery, startle response magnitude and SCL remained unchanged in all groups. Additionally, overall levels in self-reports were higher during pain-associated compared with neutral imagery, but significantly more pronounced in the pain groups compared with the control group. Results suggest that the mere imagination of pain-associated sensations elicits specific autonomic fear responses accompanied by increased self-reported fear in adolescents with chronic pain. The specific modulation of heart rate shed new light on our understanding of multimodal fear responses in adolescents with chronic pain and may help to refine paradigms to decrease fear of interoceptive sensations in chronic pain.

Temporal dynamics in mental health symptoms and loneliness during the COVID-19 pandemic in a longitudinal probability sample: a network analysis.

Figuring out which symptoms are central for symptom escalation during the COVID-19 pandemic is important for targeting prevention and intervention. Previous studies have contributed to the understanding of the course of psychological distress during the pandemic, but less is known about key symptoms of psychological distress over time. Going beyond a pathogenetic pathway perspective, we applied the network approach to psychopathology to examine how psychological distress unfolds in a period of maximum stress (pre-pandemic to pandemic onset) and a period of repeated stress (pandemic peak to pandemic peak). We conducted secondary data analyses with the Understanding Society data (N = 17,761), a longitudinal probability study in the UK with data before (2019), at the onset of (April 2020), and during the COVID-19 pandemic (November 2020 & January 2021). Using the General Health Questionnaire and one loneliness item, we computed three temporal cross-lagged panel network models to analyze psychological distress over time. Specifically, we computed (1) a pre-COVID to first incidence peak network, (2) a first incidence peak to second incidence peak network, and (3) a second incidence peak to third incidence peak network. All networks were highly consistent over time. Loneliness and thinking of self as worthless displayed a high influence on other symptoms. Feeling depressed and not overcoming difficulties had many incoming connections, thus constituting an end-product of symptom cascades. Our findings highlight the importance of loneliness and self-worth for psychological distress during COVID-19, which may have important implications in therapy and prevention. Prevention and intervention measures are discussed, as single session interventions are available that specifically target loneliness and worthlessness to alleviate mental health problems.

Anxiety sensitivity elevates the risk of mental health problems in employees with higher probability of contacting COVID-19 at work.

Individuals with increased risk of being in contact with COVID-19 cases at work have been reported to suffer from higher fear of infection and associated mental health problems. The present study examines whether this risk is further increased by higher anxiety sensitivity (AS, i.e., fear of bodily symptoms such as breathlessness, which also are core symptoms of COVID-19) that is also known to be associated with an increased risk of psychopathology. In spring 2020, 783 German health care and social workers participated in a cross-sectional online-survey, in which anxiety sensitivity, depression, anxiety, health anxiety, fear of a COVID-19 infection as well as panic symptoms were assessed. Of these participants, 28.7% affirmed contact with COVID-19 cases, which was associated with greater fear of the virus. Individuals with high AS reported more severe anxiety, health anxiety, depressive symptoms, as well as incident and recurrent panic symptoms. Moreover, the risk association of exposure to COVID-19 cases at work with health anxiety, general anxiety, and panic symptoms was further increased by higher levels of AS. These findings suggest that especially employees with contact to COVID-19 cases who also are high in AS might profit from targeted interventions to prevent excessive fear and associated mental health problems.

One year after the COVID-19 outbreak in Germany: long-term changes in depression, anxiety, loneliness, distress and life satisfaction.

Several studies have linked the COVID-19 pandemic to unfavorable mental health outcomes. However, we know little about long-term changes in mental health due to the pandemic so far. Here, we used longitudinal data from a general population sample of 1388 adults from Germany, who were initially assessed between April and May 2020 (i.e., at the beginning of the COVID-19 pandemic in Germany) and prospectively followed up after 6 (n = 1082) and 12 months (n = 945). Depressive and anxiety symptoms as well as loneliness did not change from baseline to 6-month follow-up. While anxiety symptoms did not change in the long run, depressive symptoms and loneliness increased and life satisfaction decreased from baseline to 12-month follow-up. Moreover, vulnerable groups such as younger individuals or those with a history of mental disorders exhibited an overall higher level of psychopathological symptoms across all assessment waves. Our findings suggest a deterioration in mental health during the course of the COVID-19 pandemic, which emphasizes the importance to implement targeted health promotions to prevent a further symptom escalation especially in vulnerable groups.

Defensive Mobilization During Anticipation of Symptom Provocation: Association With Panic Pathology.

BACKGROUND: Anxious apprehension about feared body symptoms is thought to play a crucial role in the development, chronicity, and treatment of panic disorder (PD). In this study, we therefore aimed to elucidate the role of defensive reactivity to anticipated unpleasant symptoms in PD that can contribute to a better understanding of pathomechanisms of PD as well as identification of potential targets in PD-focused interventions. By measuring amygdala-dependent potentiation of the startle reflex, we aimed to investigate whether 1) patients with PD exhibit a specifically increased defensive reactivity to anticipated unpleasant body symptoms and 2) whether clinical severity of panic symptomatology varies with magnitude of defensive activation. METHODS: Defensive mobilization to anticipated threat was investigated in 73 patients with a primary diagnosis of PD with agoraphobia (PDA) and 52 healthy control subjects. Threat of symptom provocation was established by a standardized hyperventilation task and contrasted to threat of shock to the forearm of the participant. RESULTS: Patients with PDA and healthy control subjects did not differ in their defensive responses during anticipation of shock. In contrast, patients with severe PDA as compared with healthy control subjects exhibited increased defensive response mobilization and reported more anxiety and panic symptoms during anticipation of feared body symptoms. Moreover, startle potentiation during anticipation of hyperventilation covaried with the severity of panic symptomatology. CONCLUSIONS: The present findings suggest that increased defensive mobilization during anticipation of body symptoms is a neurobiological correlate of severe PDA that should be specifically targeted in PD interventions and might be used to monitor treatment success.

The role of pre-pandemic depression for changes in depression, anxiety, and loneliness during the COVID-19 pandemic: Results from a longitudinal probability sample of adults from Germany.

BACKGROUND: The present study aims to delineate the role of preexisting depression for changes in common mental health problems during the COVID-19 pandemic. METHODS: Using mixed-effects linear regression models, we analyzed data on the course of depressive (Patient Health Questionnaire-2) and anxiety (Generalized Anxiety Disorder-2) symptoms as well as loneliness (three-item UCLA Loneliness Scale) in a subset of the Socio-Economic Panel Study, a large and nationally representative household panel study from Germany. Participants were assessed during the first COVID-19 wave in Germany (March 31 to July 4, 2020; n = 6,694) and prospectively followed up at the peak of the second COVID-19 wave (January 18 to February 15, 2021; n = 6,038). RESULTS: Overall, anxiety and depressive symptoms decreased, whereas loneliness increased from the first to the second COVID-19 wave. However, depressive symptoms increased and the surge in loneliness was steeper in those with versus without clinically relevant depressive symptoms in 2019 or a history of a depressive disorder before the COVID-19 pandemic. Anxiety symptoms remained stable throughout the pandemic in individuals with versus without clinically relevant depressive symptoms in 2019. Pre-pandemic depression was associated with overall higher depressive and anxiety symptoms and loneliness across both assessments. The stringency of lockdown measures did not affect the results. CONCLUSIONS: Our findings suggest that individuals with a history of depressive symptoms before the COVID-19 pandemic are at increased risk to experience an escalation of mental health problems due to the COVID-19 pandemic. Therefore, they might particularly profit from targeted prevention and early intervention programs.

Health anxiety is associated with fearful imagery of contracting COVID-19: An experimental study.

BACKGROUND: Aversive mental images of contracting or having a severe disease are assumed to contribute to the development and maintenance of health anxiety (HA) via the elicitation of fear, arousal and defensive mobilization. The current COVID-19 pandemic is known to trigger fears of contracting COVID-19. METHODS: In this study, we used an experimental approach to investigate whether COVID-19-related mental images lead to a fearful response and whether this is associated with levels of HA. 139 participants vividly imagined neutral, standard fear and COVID-19 related narrative scenes. RESULTS: Standard fear and COVID-19 scripts prompted higher anxiety, arousal, displeasure and avoidance tendencies as compared to neutral scripts. HA was associated with higher anxiety, arousal, displeasure, imagery vividness and stronger avoidance tendencies during imagery of COVID-19 scenes. No associations were found for anxiety sensitivity, trait anxiety as well as depressive and anxiety symptoms. Moreover, there was no association of HA with emotional responses during imagery of standard fear scenes. LIMITATIONS: Fear responses were assessed via verbal reports. Future studies should also assess behavioral and physiological correlates of fear. CONCLUSIONS: The present results indicate that individuals with high levels of HA are prone to fearful mental imagery of contracting COVID-19 which might be crucial factor contributing to the exacerbation and chronicity of excessive HA in times of a pandemic.

Hold your breath: Voluntary breath-holding time predicts defensive activation to approaching internal threat.

Bodily disturbances, like dyspnea, elicit responses to regain homeostasis and ensure survival. However, this life-saving function can become hyperreactive, which may lead to the emergence of psychopathology. This study investigated whether maximal voluntary breath-holding time (mvBHT), a biobehavioral marker that characterizes sensitivity to respiratory stimulation, predicts defensive mobilization to cues signaling the proximity of a mild electric shock vs. a respiratory threat (shortness of breath elicited by forced breath-holding) and the opportunity to avoid threat delivery in 60 healthy participants. While the startle reflex, a measure of defensive mobilization, generally increased with the proximity of an inevitable threat, shorter breath-holding time was specifically associated with greater startle potentiation when anticipating a respiratory threat but not an electric shock. In contrast, when both threats were avoidable, the startle reflex was comparably inhibited, irrespective of mvBHT. This study suggests that mvBHT specifically predicts hypersensitive responding to an anticipated inevitable respiratory threat.

Purchasing under threat: Changes in shopping patterns during the COVID-19 pandemic.

The spreading of COVID-19 has led to panic buying all over the world. In this study, we applied an animal model framework to elucidate changes in human purchasing behavior under COVID-19 pandemic conditions. Purchasing behavior and potential predictors were assessed in an online questionnaire format (N = 813). Multiple regression analyses were used to evaluate the role of individually Perceived Threat of COVID-19, anxiety related personality traits (trait-anxiety, intolerance of uncertainty) and the role of media exposure in predicting quantity and frequency of purchasing behavior. High levels of Perceived Threat of COVID-19 were associated significantly with a reported reduction in purchasing frequency (b = -.24, p < .001) and an increase in the quantity of products bought per purchase (b = .22, p < .001). These results are comparable to observed changes in foraging behavior in rodents under threat conditions. Higher levels of intolerance of uncertainty (b = .19, p < .001) and high extend of media exposure (b = .27, p < .001) were positively associated with Perceived Threat of COVID-19 and an increase in purchasing quantity. This study contributes to our understanding of aberrated human purchasing behavior and aims to link findings from animal research to human behavior beyond experimental investigations.

Decreased defensive reactivity to interoceptive threat after successful exposure-based psychotherapy in patients with panic disorder.

Panic disorder (PD) is characterized by a dysfunctional defensive responding to panic-related body symptoms that is assumed to contribute to the persistence of panic symptomatology. The present study aimed at examining whether this dysfunctional defensive reactivity to panic-related body symptoms would no longer be present following successful cognitive behavior therapy (CBT) but would persist when patients show insufficient symptom improvement. Therefore, in the present study, effects of CBT on reported symptoms and defensive response mobilization during interoceptive challenge were investigated using hyperventilation as a respiratory symptom provocation procedure. Changes in defensive mobilization to body symptoms in the course of CBT were investigated in patients with a primary diagnosis of PD with or without agoraphobia by applying a highly standardized hyperventilation task prior to and after a manual-based CBT (n = 38) or a waiting period (wait-list controls: n = 20). Defensive activation was indexed by the potentiation of the amygdala-dependent startle eyeblink response. All patients showed a pronounced defensive response mobilization to body symptoms at baseline. After treatment, no startle reflex potentiation was found in those patients who showed a clinically significant improvement. However, wait-list controls and treatment non-responders continued to show increased defensive responses to actually innocuous body symptoms after the treatment/waiting period. The present results indicate that the elimination of defensive reactivity to actually innocuous body symptoms might be a neurobiological correlate and indicator of successful CBT in patients with PD, which may help to monitor and optimize CBT outcomes.

Lockdown, quarantine measures, and social distancing: Associations with depression, anxiety and distress at the beginning of the COVID-19 pandemic among adults from Germany.

The COVID-19 pandemic is suggested to have a negative impact on mental health. To prevent the spread of Sars-CoV-2, governments worldwide have implemented different forms of public health measures ranging from physical distancing recommendations to stay-at-home orders, which have disrupted individuals' everyday life tremendously. However, evidence on the associations of the COVID-19 pandemic and public health measures with mental health are limited so far. In this study, we investigated the role of sociodemographic and COVID-19 related factors for immediate mental health consequences in a nationwide community sample of adults from Germany (N = 4335). Specifically, we examined the effects of different forms and levels of restriction resulting from public health measures (e.g. quarantine, stay-at-home order) on anxiety and depression symptomatology, health anxiety, loneliness, the occurrence of fearful spells, psychosocial distress and life-satisfaction. We found that higher restrictions due to lockdown measures, a greater reduction of social contacts and greater perceived changes in life were associated with higher mental health impairments. Importantly, a subjectively assumed but not an officially announced stay-at-home order was associated with poorer mental health. Our findings underscore the importance of adequate risk communication and targeted mental health recommendations especially for vulnerable groups during these challenging times.

Predictors of behavioral avoidance during respiratory symptom provocation.

Excessive anxiety and avoidance during provocation of body symptoms are core features of anxiety-related disorders and might contribute to the development and maintenance of these disorders. Previous studies examined psychological (anxiety sensitivity, fear of suffocation and trait anxiety) and biobehavioral (breath-holding time) predictors of reported anxiety during symptom provocation. However, the role of these predictors on avoidance of feared body symptoms remains unclear. Therefore, the present work aimed at investigating the main and interactive effects of psychological and biobehavioral variables in predicting avoidance during provocation of dyspnea that successively increased in severity. 28 of 69 participants prematurely terminated the provocation sequence, thus preventing further progression of symptom provocation. Logistic regressions revealed that higher anxiety sensitivity and lower breath-holding time were significantly associated with avoidance during exposure. Suffocation fear and trait anxiety were not related to avoidance. Moreover, there was a significant interaction between breath-holding time and anxiety sensitivity in predicting avoidance. Participants with a lower breath-holding time showed more avoidance behavior when reporting high as compared to low anxiety sensitivity. The data suggest that anxiety sensitivity and breath-holding time increase the risk to show avoidance and thus might contribute to the development and maintenance of anxiety-related disorders.

Defence response mobilization in response to provocation or imagery of interoceptive sensations in adolescents with chronic pain: a study protocol.

INTRODUCTION: Fear of pain seems to be a key factor in the development and maintenance of chronic pain and pain-related disability. Interoceptive fear conditioning is assumed to constitute an important mechanism in the origins and maintenance of fear of pain. If conditioned stimuli such as internal bodily sensations are repeatedly paired with pain (unconditioned stimulus), they in turn elicit a conditioned fear response, including defence mobilization such as startle modulation and changes in heart rate and electrodermal activity. Research into emotional imagery suggests that defensive responses can also be elicited through imagery of fear scripts. OBJECTIVES: We present 2 novel paradigms adapted from research on anxiety disorders, which allow to test, if perceived or imagined sensations locally proximal to the main pain location trigger heightened defence response mobilization in adolescents with chronic headaches and abdominal pain. METHODS: The provocation paradigm includes the anticipation and provocation of locally proximal and locally distal interoceptive sensations through disorder-specific muscle tensing tasks (tightening the neck or the abdominal muscles). The imagery paradigm includes 3 imagery scripts (standard neutral, standard fear, and disorder-specific). Startle probes are presented in both paradigms. Defence response mobilization is assessed using psychophysiological measures (startle response modulation, skin conductance level, and heart rate), as well as self-reported measures of fear. PERSPECTIVE: The paradigms will give insight into the defence response of adolescents with chronic pain, when confronted with or imagining interoceptive sensations. Results may inform the improvement of clinical interventions aimed to decrease fear of bodily sensations such as interoceptive exposure or interoceptive imagery exposure.

Dynamics of Defensive Response Mobilization to Approaching External Versus Interoceptive Threat.

BACKGROUND: Excessive fear and anxiety are core features of anxiety disorders. Defensive response mobilization varies dynamically with threat proximity. METHODS: We analyzed defensive responses in 48 healthy students to an approaching external, predator-like threat (an electric shock resembling a predator attack) versus an approaching threat from inside the body (feeling of dyspnea as evoked by forced breath-holding). Threats either were inevitable or could be avoided by button press. RESULTS: Autonomic changes (heart rate, skin conductance), defensive reflex priming (startle eyeblink response), respiratory responses, and event-related potentials were assessed. Regardless of its source, when an approaching threat was inevitable, a defensive pattern emerged characterized by an increase in skin conductance, a potentiation of the startle reflex, and bradycardia. Minute ventilation increased only with approaching dyspnea. In preparation for active avoidance of either threat, startle magnitudes were inhibited and probe-elicited P3 wave amplitudes were reduced. Moreover, generation of avoidant action resulted in heart rate acceleration. CONCLUSIONS: This study demonstrates common and specific defensive activation patterns for approaching external and respiratory threats. The specific modulation in respiration in response to an inevitable respiratory threat may have important implications for our understanding of the etiology of anxiety disorders, especially panic disorder.

Cue and context conditioning to respiratory threat: Effects of suffocation fear and implications for the etiology of panic disorder.

Interoceptive threats play a crucial role in the etiology of panic disorder (PD). While body sensations may become conditioned stimuli (CS) when paired with such interoceptive threats (cue conditioning), the environment in which such interoceptive threats occur may also be learned as a predictor of threat (context conditioning). Suffocation fear (SF) might facilitate these associative learning processes if threats of suffocation become relevant as unconditioned stimuli (US). To investigate whether SF affects associative learning during such respiratory threat, we used mild dyspnea as CS that predicted the occurrence of strong dyspnea (US) in one context (predictable), was not related to the occurrence of the US in another context (unpredictable) or was presented in a different context (safe) in which no US was delivered. Startle eyeblink responses and subjective reports were assessed in 34 participants during learning. Individuals reporting high SF showed a clear potentiation of the startle response during the interoceptive CS predicting the occurrence of interoceptive threat (US). Such startle potentiation was not observed when the CS remained unpaired (safe or unpredictable context). Moreover, high SF persons also showed a significant startle potentiation to the threatening context, when the CS did not predict the onset of the US. No such learning effects were observed for low SF individuals. The data support the view that defensive response mobilization can be triggered by cues but also by contexts that predict the occurrence of interoceptive threats if these threats are relevant for the individuals, supporting learning accounts for the development of PD.

Dynamics of defensive response mobilization during repeated terminations of exposure to increasing interoceptive threat.

Resistant avoidance behaviors play a crucial role in the maintenance of anxiety disorders and are therefore central targets of therapeutic interventions. In the present study, the development of avoidance behavior was investigated in 24 healthy participants who repeatedly prematurely terminated the exposure to increasing interoceptive threat, i.e., the feeling of dyspnea induced by increasing inspiratory resistive loads that were followed by the ultimate threat, a short breathing occlusion. Physiological responses and subjective anxiety preceding terminations were compared to matched intervals of a matched control group (N=24) who completed the exposure. Initially, participants terminated during the ultimate threat, i.e., during occlusion. This first termination was preceded by a strong surge in autonomic arousal and reported anxiety. Startle reflex and the P3 component of event-related brain potentials to startle probes were strongly inhibited, indicating preparation for defensive action. With repetitive terminations, individuals successively terminated earlier, avoiding exposure to the occlusion. This avoidant behavior was accompanied by alleviated autonomic arousal as compared to the first termination. In addition, no indication of physiological response preparation was found implying that the avoidance behavior was performed in a rather habitual way. Matched controls did not show any indication of a defensive response surge in the matched intervals. In matched controls, no changes in physiological response patterns were detected while anxiety levels increased with repetitions. The present results shed new light on our understanding of the motivational basis of avoidance behavior and may help to refine etiological models, behavioral analysis and therapeutic strategies in treating anxiety disorders.