The human fear-circuitry and fear-induced fainting in healthy individuals

An ethologically based view into human fear

The quality of the defensive response to a threat depends on the elements that trigger the fear response. The current classification system of phobias does not account for this. Here, we analyze the fear-eliciting elements and discern the different types of fears that originate from them. We propose Pain, Disgust, Vasovagal response, Visual-vestibular and postural interactions, Movement and Speed, Distance and Size, Low and mid-level visual features, Smell, and Territory and social status. We subdivide phobias according to the fear-eliciting elements most frequently triggered by them and their impact on behavior. We discuss the implications of a clinical conceptualization of phobias in humans by reconsidering the current nosology. This conceptualization will facilitate finding etiological factors in defensive behavior expression, fine-tuning exposure techniques, and challenging preconceived notions of preparedness. This approach to phobias leads to surprising discoveries and shows how specific responses bear little relation to the interpretation we might later give to them. Dividing fears into their potentially fear-eliciting elements can also help in applying the research principles formulated by the Research Domain Criteria initiative.

Influence of Controlled Stomatognathic Motor Activity on Sway, Control and Stability of the Center of Mass During Dynamic Steady-State Balance—An Uncontrolled Manifold Analysis

Multiple sensory signals from visual, somatosensory and vestibular systems are used for human postural control. To maintain postural stability, the central nervous system keeps the center of mass (CoM) within the base of support. The influence of the stomatognathic motor system on postural control has been established under static conditions, but it has not yet been investigated during dynamic steady-state balance. The purpose of the study was to investigate the effects of controlled stomatognathic motor activity on the control and stability of the CoM during dynamic steady-state balance. A total of 48 physically active and healthy adults were assigned to three groups with different stomatognathic motor conditions: jaw clenching, tongue pressing and habitual stomatognathic behavior. Dynamic steady-state balance was assessed using an oscillating platform and the kinematic data were collected with a 3D motion capturing system. The path length (PL) of the 3D CoM trajectory was used for quantifying CoM sway. Temporal dynamics of the CoM movement was assessed with a detrended fluctuation analysis (DFA). An uncontrolled manifold (UCM) analysis was applied to assess the stability and control of the CoM with a subject-specific anthropometric 3D model. The statistical analysis revealed that the groups did not differ significantly in PL, DFA scaling exponents or UCM parameters. The results indicated that deliberate jaw clenching or tongue pressing did not seem to affect the sway, control or stability of the CoM on an oscillating platform significantly. Because of the task-specificity of balance, further research investigating the effects of stomatognathic motor activities on dynamic steady-state balance with different movement tasks are needed. Additionally, further analysis by use of muscle synergies or co-contractions may reveal effects on the level of muscles, which were not visible on the level of kinematics. This study can contribute to the understanding of postural control mechanisms, particularly in relation to stomatognathic motor activities and under dynamic conditions.

The shielding effect of not responding: Peritraumatic responses to child abuse and their links to posttraumatic symptomatology

BACKGROUND

Extensive literature focuses on peritraumatic responses to trauma and their link to subsequent posttraumatic symptomatology. However, although posttraumatic symptomatology following child abuse (CA) has been documented, research on peritraumatic responses to CA is sparse.

OBJECTIVE

The current study utilizes a new typology of peritraumatic responses to CA and tests whether automatic and behavioral peritraumatic responses to CA differ in their long-term implications for posttraumatic symptomatology, i.e., posttraumatic stress (PTS symptoms), deficiency in self-organization (DSO symptoms; complex posttraumatic symptoms), and dissociation.

PARTICIPANTS, SETTINGS AND METHODS

One-hundred and eighty adult CA survivors reported on CA, peritraumatic responses, PTS symptoms, DSO symptoms, and dissociation.

RESULTS

The tendency to freeze and dissociate, and utilize extensive behavioral methods to survive the abuse were implicated in higher posttraumatic symptomatology (F(2,178) > 4.26, p < 0.01). The absence of automatic and behavioral responses were found to be implicated in the lowest levels of posttraumatic symptomatology (p < 0.01) and to buffer the effect of CA severity on PTS and DSO posttraumatic symptoms (0.047 > effect>0.029, p < 0.001).

CONCLUSIONS

The findings uncovered a novel response pattern, reflected in a tendency to eradicate responses to CA, which was the most protective in regard to its link to later posttraumatic symptomatology. Contrarily, the most scarring peritraumatic responses to CA that arose from the findings were the tendency to freeze and dissociate and utilize various excessive behavioral methods to endure the abuse. These findings imply that CA generates several possible responses, some of which, although allowing for survival in childhood, have adverse effects in adulthood.

Fear of Injections and Needle Phobia Among Children and Adolescents: An Overview of Psychological, Behavioral, and Contextual Factors

The purpose of this clinical update is to provide an overview of the fear of needles and needle phobia in children and adolescents including characteristics and diagnosis, prevalence and epidemiology, etiological factors, and treatment options. Needle-related fear and needle phobia present as significant needle-related distress and avoidance behavior. The etiology is biopsychosocial. These challenging conditions are more common in children and adolescents than in adults. The nurse–patient relationship enables the provision of suitable preparation before injection procedures. Nurses can use exposure-based interventions and incorporate coping strategies and teaching of parents and children. Nurses play a pivotal role in noticing the need for further treatment. Procedural needle-related distress is a complex phenomenon representing a continuum ranging from needle fear to more severe needle phobia. For patients with needle fear management and training methods used by nurses can possibly prevent a progression of the condition into needle phobia. In cases of needle phobia, a correct diagnosis made by a psychiatrist is necessary and enables referral to a psychotherapist with experience in treating children and adolescents with needle phobia.

Typical vasovagal syncope as a "defense mechanism" for the heart by contrasting sympathetic overactivity

Many observations suggest that typical (emotional or orthostatic) vasovagal syncope (VVS) is not a disease, but rather a manifestation of a non-pathological trait. Some authors have hypothesized this type of syncope as a "defense mechanism" for the organism and a few theories have been postulated. Under the human violent conflicts theory, the VVS evolved during the Paleolithic era only in the human lineage. In this evolutionary period, a predominant cause of death was wounding by a sharp object. This theory could explain the occurrence of emotional VVS, but not of the orthostatic one. The clot production theory suggests that the vasovagal reflex is a defense mechanism against hemorrhage in mammals. This theory could explain orthostatic VVS, but not emotional VVS. The brain self-preservation theory is mainly based on the observation that during tilt testing a decrease in cerebral blood flow often precedes the drop in blood pressure and heart rate. The faint causes the body to take on a gravitationally neutral position, and thereby provides a better chance of restoring brain blood supply. However, a decrease in cerebral blood flow has not been demonstrated during negative emotions, which trigger emotional VVS. Under the heart defense theory, the vasovagal reflex seems to be a protective mechanism against sympathetic overactivity and the heart is the most vulnerable organ during this condition. This appears to be the only unifying theory able to explain the occurrence of the vasovagal reflex and its associated selective advantage, during both orthostatic and emotional stress.

Vasovagal Syncope: Hypothesis Focusing on Its Being a Clinical Feature Unique to Humans

Humans live primarily in the upright position; as a result, there is a constant struggle between gravity and needed supply of blood flow to the brain. In certain circumstances brain blood supply may become temporarily insufficient, resulting in syncope. Among the numerous causes of syncope in humans, vasovagal syncope (VVS) is by far the most common. However, despite intensive research, many aspects of the pathophysiology of VVS remain unknown; among these, one of the least well understood is the basis for why VVS is restricted, among vertebrates, to Homo sapiens. In this manuscript we review proposals that have been offered in an attempt to address the issue of the origin of VVS and, although highly speculative, we suggest a new hypothesis (the "brain theory") to try to address the question of why humans, to the exclusion of other species, remain susceptible to VVS. This theory suggests that VVS evolved to offer protection to the brain's functional integrity under certain conditions of severe threat. Although seemingly a disadvantageous evolutionary adaptation, the faint causes the body to take on a gravitationally neutral position, and thereby provides a better chance of restoring brain blood supply and preserving long-term brain function.

Brainstem dysfunction protects against syncope in multiple sclerosis

BACKGROUND

The aim of this study was to investigate the correlation between autonomic dysfunction in multiple sclerosis (MS) and brainstem dysfunction evaluated with the vestibular evoked myogenic potentials (VEMP) score and conventional MRI.

METHODS

Forty-five patients with the diagnosis of clinically isolated syndrome (CIS) suggestive of MS were enrolled. VEMP, heart rate, and blood pressure responses to the Valsalva maneuver, heart rate response to deep breathing, and pain provoked head-up tilt table test, as well as brain and spinal cord MRI were performed.

RESULTS

There was no difference in the VEMP score between patients with and without signs of sympathetic or parasympathetic dysfunction. However, patients with syncope had significantly lower VEMP score compared to patients without syncope (p<0.01). Patients with orthostatic hypotension (OH) showed a trend of higher VEMP score compared to patients without OH (p=0.06). There was no difference in the presence of lesions in the brainstem or cervical spinal cord between patients with or without any of the studied autonomic parameters. The model consisting of a VEMP score of ≤5 and normal MRI of the midbrain and cervical spinal cord has sensitivity and specificity of 83% for the possibility that the patient with MS can develop syncope.

CONCLUSIONS

Pathophysiological mechanisms underlying functional and structural disorders of autonomic nervous system in MS differ significantly. While preserved brainstem function is needed for development of syncope, structural disorders like OH could be associated with brainstem dysfunction.

Fear and the Defense Cascade: Clinical Implications and Management

Evolution has endowed all humans with a continuum of innate, hard-wired, automatically activated defense behaviors, termed the defense cascade. Arousal is the first step in activating the defense cascade; flight or fight is an active defense response for dealing with threat; freezing is a flight-or-fight response put on hold; tonic immobility and collapsed immobility are responses of last resort to inescapable threat, when active defense responses have failed; and quiescent immobility is a state of quiescence that promotes rest and healing. Each of these defense reactions has a distinctive neural pattern mediated by a common neural pathway: activation and inhibition of particular functional components in the amygdala, hypothalamus, periaqueductal gray, and sympathetic and vagal nuclei. Unlike animals, which generally are able to restore their standard mode of functioning once the danger is past, humans often are not, and they may find themselves locked into the same, recurring pattern of response tied in with the original danger or trauma. Understanding the signature patterns of these innate responses--the particular components that combine to yield the given pattern of defense-is important for developing treatment interventions. Effective interventions aim to activate or deactivate one or more components of the signature neural pattern, thereby producing a shift in the neural pattern and, with it, in mind-body state. The process of shifting the neural pattern is the necessary first step in unlocking the patient's trauma response, in breaking the cycle of suffering, and in helping the patient to adapt to, and overcome, past trauma.

Vasovagal Syncope As A Manifestation Of An Evolutionary Selected Trait

Some observations suggest that typical (emotional or orthostatic) vasovagal syncope (VVS) is not a disease, but rather a manifestation of a non-pathological trait. We conducted an extensive bibliographic research on the vasovagal reactions in animals, including humans, in order to investigate the possible factors that may explain the origin and evolution of VVS. We found two processes which appear relevant for the investigation of VVS evolution: fear/threat bradycardia (alarm bradycardia) in animals, mainly during tonic immobility and vasovagal reflex during hemorrhagic shock (thoracic hypovolemia) both in animals and humans. The available data suggest that VVS in humans, alarm bradycardia in animals and the vasovagal reflex during hemorrhagic shock share the same physiological mechanisms and that is indicative of a common evolutionary root. However, during the vasovagal reflex loss of consciousness occurs in humans, but it is absent (or extremely rare) in animals. That can be explained as a by-product due to the erect position and the large brain evolved in our species. If the vasovagal reflex persisted for millions of years along the vertebrates evolutionary history, we can reasonably assume that it has a function and it is not harmful. It could be neutral or beneficial, but the available data suggest it is beneficial; likely, it evolved as an advantageous response to stressful and possibly dangerous heart conditions. Emotional or orthostatic vasovagal reflex is preceded by enhanced sympathetic activity, which is harmful and possibly dangerous. The transient inhibition of the sympathetic system, together with activation of the vagal tone , characterizes VVS. The consequent slowing of the heart rate induced by the vasovagal reflex may constitute a beneficial break of the cardiac pump, thereby reducing myocardial oxygen consumption. We suggest that typical VVS should be regarded as a selected response, which probably evolved in the ancient past as a defense mechanism of the organism within some ancestral group(s) of vertebrates.

The origin of vasovagal syncope: to protect the heart or to escape predation?

Major lines of evidence suggest that classical (emotional and orthostatic) vasovagal syncope (VVS) is not a disease, but rather a manifestation of a non-pathological trait. It is, therefore, reasonable to investigate the possible factors that may explain its origin and evolution. We reviewed the data available in the literature on the vasovagal reaction in humans and animals in order to identify possible similarities that might provide insight into the evolution of VVS. We found two processes which appear relevant to the investigation of VVS evolution: fear and threat bradycardia in animals, and the vasovagal reflex during hemorrhagic shock in humans and animals. We suggest that VVS in humans involves physiological mechanisms similar to those found in other vertebrates, and that this may indicate a common evolutionary root. The available data seem to suggest that VVS evolved as an advantageous response to inescapable predators or to stressful and possibly dangerous heart conditions. The inhibition of the sympathetic system, together with activation of the vagal system, characterizes VVS. The consequent slowing of the heart rate induced by VVS may constitute a beneficial break of the cardiac pump, thereby reducing myocardial oxygen consumption. We suggest that classical VVS did not evolve recently in the modern human lineage; rather, it should be regarded as a selected response, which probably evolved in the ancient past as a "defense mechanism" of the organism within some ancestral group(s) of vertebrates.

Cerebral Autoregulation and Syncope

Whatever the pathogenesis of syncope is, the ultimate common cause leading to loss of consciousness is insufficient cerebral perfusion with a critical reduction of blood flow to the reticular activating system. Brain circulation has an autoregulation system that keeps cerebral blood flow constant over a wide range of systemic blood pressures. Normally, if blood pressure decreases, autoregulation reacts with a reduction in cerebral vascular resistance, in an attempt to prevent cerebral hypoperfusion. However, in some cases, particularly in neurally mediated syncope, it can also be harmful, being actively implicated in a paradox reflex that induces an increase in cerebrovascular resistance and contributes to the critical reduction of cerebral blood flow. This review outlines the anatomic structures involved in cerebral autoregulation, its mechanisms, in normal and pathologic conditions, and the noninvasive neuroimaging techniques used in the study of cerebral circulation and autoregulation. An emphasis is placed on the description of autoregulation pathophysiology in orthostatic and neurally mediated syncope.

Utility of fear severity and individual resilience scoring as a surge capacity, triage management tool during large-scale, bio-event disasters

Threats of bioterrorism and emerging infectious disease pandemics may result in fear-related consequences. If left undetected and untreated, fear-based signs and symptoms may be extremely debilitating and lead to chronic problems with a risk of permanent damage to the brain's locus coeruleus and stress response circuits. The triage management of susceptible, exposed, and infectious victims seeking care must be sensitive and specific enough to identify individuals with excessive levels of fear in order to address the nuances of fear-based symptoms at the initial point of contact. These acute conditions, which include hyper-vigilant fear, are managed best by timely and effective information, rapid evaluation, and possibly medications that uniquely address the locus-coeruleus-driven noradrenalin over-activation. It is recommended that a Fear and Resilience (FR) Checklist be included as an essential triage tool to identify those most at risk. The use of this checklist facilitates an enhanced capacity to respond to limitations brought about by surge capacity requirements. Whereas the utility of such a checklist is evident, predictive validity studies will be required. In addition to identifying individuals who are emotionally, medically, and socially hypo-resilient, the FR Checklist simultaneously identifies individuals who are hyper-resilient and can be asked to volunteer, and thus, rapidly expand the surge capacity.

Testing the Paleolithic-human-warfare hypothesis of blood-injection phobia in the Baltimore ECA Follow-up Study--towards a more etiologically-based conceptualization for DSM-V

OBJECTIVE

The research agenda for the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) has emphasized the need for a more etiologically-based classification system, especially for stress-induced and fear-circuitry disorders. Testable hypotheses based on threats to survival during particular segments of the human era of evolutionary adaptedness (EEA) may be useful in developing a brain-evolution-based classification for the wide spectrum of disorders ranging from disorders which are mostly overconsolidationally such as PTSD, to fear-circuitry disorders which are mostly innate such as specific phobias. The recently presented Paleolithic-human-warfare hypothesis posits that blood-injection phobia can be traced to a "survival (fitness) enhancing" trait, which evolved in some females of reproductive-age during the millennia of intergroup warfare in the Paleolithic EEA. The study presented here tests the key a priori prediction of this hypothesis-that current blood-injection phobia will have higher prevalence in reproductive-age women than in post-menopausal women.

METHOD

The Diagnostic Interview Schedule (version III-R), which included a section on blood and injection phobia, was administered to 1920 subjects in the Baltimore ECA Follow-up Study.

RESULTS

Data on BII phobia was available on 1724 subjects (1078 women and 646 males). The prevalence of current blood-injection phobia was 3.3% in women aged 27-49 and 1.1% in women over age 50 (OR 3.05, 95% CI 1.20-7.73). [The corresponding figures for males were 0.8% and 0.7% (OR 1.19, 95% CI 0.20-7.14)].

CONCLUSIONS

This epidemiological study provides one source of support for the Paleolithic-human-warfare (Paleolithic-threat) hypothesis regarding the evolutionary (distal) etiology of bloodletting-related phobia, and may contribute to a more brain-evolution-based re-conceptualization and classification of this fear circuitry-related trait for the DSM-V. In addition, the finding reported here may also stimulate new research directions on more proximal mechanisms which can lead to the development of evidence-based psychopharmacological preventive interventions for this common and sometimes disabling fear-circuitry disorder.

Human brain evolution and the "Neuroevolutionary Time-depth Principle:" Implications for the Reclassification of fear-circuitry-related traits in DSM-V and for studying resilience to warzone-related posttraumatic stress disorder

The DSM-III, DSM-IV, DSM-IV-TR and ICD-10 have judiciously minimized discussion of etiologies to distance clinical psychiatry from Freudian psychoanalysis. With this goal mostly achieved, discussion of etiological factors should be reintroduced into the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V). A research agenda for the DSM-V advocated the "development of a pathophysiologically based classification system". The author critically reviews the neuroevolutionary literature on stress-induced and fear circuitry disorders and related amygdala-driven, species-atypical fear behaviors of clinical severity in adult humans. Over 30 empirically testable/falsifiable predictions are presented. It is noted that in DSM-IV-TR and ICD-10, the classification of stress and fear circuitry disorders is neither mode-of-acquisition-based nor brain-evolution-based. For example, snake phobia (innate) and dog phobia (overconsolidational) are clustered together. Similarly, research on blood-injection-injury-type-specific phobia clusters two fears different in their innateness: 1) an arguably ontogenetic memory-trace-overconsolidation-based fear (hospital phobia) and 2) a hardwired (innate) fear of the sight of one's blood or a sharp object penetrating one's skin. Genetic architecture-charting of fear-circuitry-related traits has been challenging. Various, non-phenotype-based architectures can serve as targets for research. In this article, the author will propose one such alternative genetic architecture. This article was inspired by the following: A) Nesse's "Smoke-Detector Principle", B) the increasing suspicion that the "smooth" rather than "lumpy" distribution of complex psychiatric phenotypes (including fear-circuitry disorders) may in some cases be accounted for by oligogenic (and not necessarily polygenic) transmission, and C) insights from the initial sequence of the chimpanzee genome and comparison with the human genome by the Chimpanzee Sequencing and Analysis Consortium published in late 2005. Neuroevolutionary insights relevant to fear circuitry symptoms that primarily emerge overconsolidationally (especially Combat related Posttraumatic Stress Disorder) are presented. Also introduced is a human-evolution-based principle for clustering innate fear traits. The "Neuroevolutionary Time-depth Principle" of innate fears proposed in this article may be useful in the development of a neuroevolution-based taxonomic re-clustering of stress-triggered and fear-circuitry disorders in DSM-V. Four broad clusters of evolved fear circuits are proposed based on their time-depths: 1) Mesozoic (mammalian-wide) circuits hardwired by wild-type alleles driven to fixation by Mesozoic selective sweeps; 2) Cenozoic (simian-wide) circuits relevant to many specific phobias; 3) mid Paleolithic and upper Paleolithic (Homo sapiens-specific) circuits (arguably resulting mostly from mate-choice-driven stabilizing selection); 4) Neolithic circuits (arguably mostly related to stabilizing selection driven by gene-culture co-evolution). More importantly, the author presents evolutionary perspectives on warzone-related PTSD, Combat-Stress Reaction, Combat-related Stress, Operational-Stress, and other deployment-stress-induced symptoms. The Neuroevolutionary Time-depth Principle presented in this article may help explain the dissimilar stress-resilience levels following different types of acute threat to survival of oneself or one's progency (aka DSM-III and DSM-V PTSD Criterion-A events). PTSD rates following exposure to lethal inter-group violence (combat, warzone exposure or intentionally caused disasters such as terrorism) are usually 5-10 times higher than rates following large-scale natural disasters such as forest fires, floods, hurricanes, volcanic eruptions, and earthquakes. The author predicts that both intentionally-caused large-scale bioevent-disasters, as well as natural bioevents such as SARS and avian flu pandemics will be an exception and are likely to be followed by PTSD rates approaching those that follow warzone exposure. During bioevents, Amygdala-driven and locus-coeruleus-driven epidemic pseudosomatic symptoms may be an order of magnitude more common than infection-caused cytokine-driven symptoms. Implications for the red cross and FEMA are discussed. It is also argued that hospital phobia as well as dog phobia, bird phobia and bat phobia require re-taxonomization in DSM-V in a new "overconsolidational disorders" category anchored around PTSD. The overconsolidational spectrum category may be conceptualized as straddling the fear circuitry spectrum disorders and the affective spectrum disorders categories, and may be a category for which Pitman's secondary prevention propranolol regimen may be specifically indicated as a "morning after pill" intervention. Predictions are presented regarding obsessive-compulsive disorder (OCD) (e.g., female-pattern hoarding vs. male-pattern hoarding) and "culture-bound" acute anxiety symptoms (taijin-kyofusho, koro, shuk yang, shook yong, suo yang, rok-joo, jinjinia-bemar, karoshi, gwarosa, Voodoo death). Also discussed are insights relevant to pseudoneurological symptoms and to the forthcoming Dissociative-Conversive disorders category in DSM-V, including what the author terms fright-triggered acute pseudo-localized symptoms (i.e., pseudoparalysis, pseudocerebellar imbalance, psychogenic blindness, pseudoseizures, and epidemic sociogenic illness). Speculations based on studies of the human abnormal-spindle-like, microcephaly-associated (ASPM) gene, the microcephaly primary autosomal recessive (MCPH) gene, and the forkhead box p2 (FOXP2) gene are made and incorporated into what is termed "The pre-FOXP2 Hypothesis of Blood-Injection-Injury Phobia." Finally, the author argues for a non-reductionistic fusion of "distal (evolutionary) neurobiology" with clinical "proximal neurobiology," utilizing neurological heuristics. It is noted that the value of re-clustering fear traits based on behavioral ethology, human-phylogenomics-derived endophenotypes and on ontogenomics (gene-environment interactions) can be confirmed or disconfirmed using epidemiological or twin studies and psychiatric genomics.